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Carbon Vs Aluminum Wheels: Pros and Cons

Your wheels are arguably the most important individual component of your bicycle when it comes to performance. Upgrading from entry-level to premium wheels can reduce weight, increase speed, and improve the overall performance of any bike. When choosing bike wheels, one of the most important decisions you’ll have to make is which material to go with. The two most common bike wheel materials include aluminum and carbon fiber. To help you choose, this guide outlines the pros and cons of carbon vs aluminum wheels. We’ll cover weight, stiffness, ride quality, durability, cost, handling, longevity, and much more. We’ll also outline the different types of wheels including clincher, tubeless, and tubular as well as talk a bit about hubs and spokes. 

Two cyclists riding down a mountain road during sunset

Most bikes are sold with low-end to mid-range aluminum wheels. The benefit of this is that it keeps costs down. Unfortunately, these aluminum wheels don’t perform very well because they are heavy and flexible.

By upgrading to carbon fiber wheels or premium aluminum wheels, you can greatly improve your bike’s performance and ride quality. High-end wheels are lighter, stiffer, more aerodynamic, and more supportive. They allow you to ride faster and more efficiently. 

Of course, not everyone needs expensive carbon wheels. There are also compromises to make when using carbon fiber wheels. They are typically less durable and long-lasting. Roots and rocks on the trail can cause rim damage. Some models can be overly stiff and uncomfortable.

The best type of wheels for your bike depends on a number of factors including the type of riding you do, the terrain you ride, your budget, and personal preference. Hopefully, this guide helps you choose the best wheels for your style of riding.

Carbon Fiber Bike Wheels

Carbon fiber is the most commonly used material for building high-end and high-performance road and mountain bike wheels. These days, almost all professional racing bikes use carbon wheels. For competitive riders, carbon wheels are often the only choice. 

Carbon fiber is a lightweight, rigid, and strong material that was originally developed for use in the aerospace industry. It is made from ultra-strong fibers that are woven into sheets and bound together with epoxy resin. In other words, it is a plastic that is reinforced with strong fibers. It is a composite material. Carbon fiber is the lightest material used to build bicycle wheels. 

A mountain bike wheel with carbon fiber rims

Carbon fiber is made by processing a polymer into thin filaments made of carbon atoms. The filaments measure just 5-10 microns in diameter. Thousands of these filaments are combined to form a tow or ribbon. These ribbons are woven together into a sheet and impregnated with epoxy resin. 

The resulting sheets of carbon fiber are trimmed to size with a precision cutting machine. The pieces are then layered and shaped into bicycle rims using a mold. Rim manufacturers can use modern technology such as computer modeling and 3D printed molds to shape wheels with incredible precision. 

Next, the carbon fiber sheets and mold are heated up in an oven. The wheels are heated in a special heating cycle called a ramp cycle. The heat starts at a low temperature and ramps up over time then cools off. The temperature and heating time are precisely controlled. This process melts and combines the layers into a single piece and hardens the wheels. When the wheels come out of the oven, they are finished. 

Not all carbon fiber wheels are equal. There is quite a bit of variation in the way that carbon wheels are built and the way the carbon fiber itself is made. For example, manufacturers can vary the type of resin used, the direction of the fibers, the weave of the fibers, the density and types of fibers used, the grade of carbon fiber, the thickness of the layers, the number of filaments per tow, the way the material is heated and molded, etc. 

All of these variations play a role in the stiffness, weight, and durability of the finished wheels. This can affect the wheel’s weight, the bike’s handling, ride characteristics, and comfort. Manufacturers can optimize carbon wheels for different types of riding. For example, a road wheel could be made stiffer and an off-road wheel could be made flexible.

For more info about how carbon fiber bike wheels are made, check out this interesting article.

Aluminum Bike Wheels

Aluminum is, by far, the most common bike wheel material. Pretty much all bikes, other than a few top-of-the-line models, come from the factory with aluminum rims. Aluminum is a lightweight, stiff, durable, and affordable material. 

A bike with aluminum rims

Aluminum itself isn’t strong enough for building bike wheels. To increase strength and durability, aluminum is alloyed with other metallic elements such as magnesium, zinc, or silicon.

Different alloys offer slightly different characteristics. Some alloys are stiffer than others. Some are lighter or more resilient than others. The alloy plays a major role in the ride quality, weight, and durability of the rim.

The two most common aluminum alloys used for building bike rims include 6061 and 7005. Of the two, 6061 is a bit more common because it weighs less. A higher-end alloy, called niobium, is also used.  

Aluminum rims start as a block of metal. This material is melted and pressed through a pre-made die that is shaped like a cross-section of the rim. The die shape determines the rim shape and wall thickness. This plays a big role in the weight and performance of the finished wheels. 

The material exits the die in a long, straight, straight section of rim. The rims are then cut to length for the appropriate wheel diameter (700c, 26”, 20″, etc.). Next, the sections are bent into perfect circles.

The ends of the rims are then joined together. A couple of different methods can be used to do this. For higher-end rims, a computerized welding machine welds the ends of the rim together in such a way that the seam is nearly invisible. Another method is called plugging and pinning. This is common on mid-range and lower-end rims.

Finally, the rims are finished. Spoke and valve holes are drilled. Braking tracks are machined into the sides to improve braking performance on wheels designed for rim brakes. Some rims are painted or clear coated for extra protection.

Pros and Cons of Carbon Fiber Wheels

Pros

  • Lighter weight- Carbon wheels weigh 300 grams (10.6 oz) less than aluminum on average.
  • Better handling- Stiff carbon wheels are responsive.
  • Faster- The lighter wheels spin up faster.
  • More efficient- It takes less energy to ride lighter and stiffer wheels.
  • Better aerodynamics- Carbon rims can be molded into deep aero shapes.
  • Carbon wheels stay true longer- The rigid maintain their shape well because tolerances are lower.
  • Better overall ride quality- Carbon wheels make a good compromise between weight, rigidity, performance, and comfort.

Cons

  • Less durable- Carbon rims are brittle. A rim strike can crack carbon rims.
  • More expensive- A carbon wheelset costs around $1000 more than an aluminum wheelset.
  • Harsh ride- Some carbon wheels are overly stiff. This makes the ride feel rough.
  • Not repairable- If your carbon rim cracks you need to replace it.
  • Less environmentally friendly- Carbon fiber can’t be recycled.
  • Overheating- Carbon rims can overheat on long descents and fail.
  • Less long lasting- Carbon rims can crack or overheat and fail prematurely.
  • Less reliable- carbon wheels can fail and leave you stranded.

Pros and Cons of Aluminum Wheels

Pros

  • More durable- Aluminum wheels can handle harder impact forces without sustaining damage.
  • Cheaper- Aluminum wheels cost less than half as much as carbon fiber. Entry level models start at $150.
  • Repairable- Dented aluminum wheels can often be bent back into shape.
  • Comfort- Aluminum wheels can absorb some shocks and vibrations.
  • Safer- Aluminum dissipates heat better. This makes the wheels less likely to overheat and fail.
  • More environmentally friendly- Aluminum can be recycled.
  • More reliable- Aluminum rims are less likely to break and leave you stranded.
  • Longevity- Due to their durability, aluminum rims usually last longer than carbon.

Cons

  • Heavier- Aluminum wheels are denser and require more material so they weigh more.
  • More flexible- The flex makes the wheels less responsive to rider inputs.
  • Slower- The heavier wheels spin up slower.
  • Less aerodynamic- Aluminum rims can’t be molded into deep aero shapes.
  • Less efficient- It takes more energy to ride aluminum rims due to the extra weight and flex.
  • Aluminum wheels need to be trued more often- The more flexible rims lose their shape more easily.
A road cyclist riding down a highway shoulder

Carbon Vs Aluminum Wheels

When buying a new set of wheels, the rim material is one of the most important choices you’ll have to make. Both carbon fiber and aluminum can be used to build lightweight, stiff, and high-performance rims. Both materials have their own strengths and weaknesses. In this section, we’ll compare the differences between carbon fiber and aluminum bicycle wheels to help you decide.

Carbon Vs Aluminum Wheel Weight

Carbon fiber wheels are lighter than comparable aluminum wheels. For example, many manufacturers offer carbon wheels that weigh 1300-1500 grams. The lightest carbon wheels weigh less than 1000 grams.

To compare, lightweight aluminum wheels weigh around 1600-1700 grams. On average, you’ll save around 300 grams (10.6 oz) by switching from aluminum to carbon fiber wheels. For many cyclists, anything over half a pound is considered a significant weight saving. 

Carbon fiber wheels are lighter because the material is less dense. The density of modern carbon fiber is about 1.9 grams per cm^3 while the density of aluminum is about 2.7 grams per cm^3. It’s almost half as dense. Carbon fiber is also incredibly strong. It has a higher strength-to-weight ratio than steel or aluminum. 

The wheels are the best place to cut weight from a bicycle. The reason is that wheels are rotating mass. Lighter wheels have less rotating mass. The lower rotating mass means the wheels have less inertia. It takes less energy to overcome the inertia when the wheels are lighter. With heavier wheels, it takes more energy to overcome the inertia. 

Lighter wheels require less energy to accelerate. Once the bike is moving, it takes less energy to maintain your speed. This makes the bike faster and more efficient to ride. You’ll be able to ride further while burning less energy.

As an added benefit, you’ll be able to stop faster. The lighter wheels can slow down faster as well. This allows you to start braking later before a turn, saving you time.

In other words, lighter carbon wheels allow you to ride faster and more efficiently than heavier aluminum wheels. The lighter wheels spin up faster and with less effort because there is less weight to move around. They feel snappier and more responsive. This allows you to accelerate, climb, brake, and maneuver faster. This is particularly useful for riding in stop-and-go city traffic, climbing steep hills, or taking corners. You can get back up to speed much faster after slowing down or stopping.

Cyclists racing

When you upgrade to lighter wheels, you will immediately be able to feel the difference. Reducing 300 grams from your wheels is much more noticeable than reducing 300 grams from a static part of your bike.

This weight savings is important if you ride competitively or track your time. You might cut a few seconds off of a long climb by switching to lightweight carbon fiber wheels. This can give you a competitive advantage. You very well may set a new personal record after upgrading to lightweight carbon wheels. 

It’s important to note that the manufacturer’s claimed weight and actual weight of wheels often differ. This can be due to inconsistencies in manufacturing. For example, aluminum wheel dies produce heavier wheels as they age because part of the die wears away, allowing the rims to come out thicker. If you’re upgrading your wheels to cut weight, it’s important to weigh the actual wheels you’re installing to get an accurate measurement. 

Winner: Carbon fiber wheels are lighter than aluminum wheels.

Carbo Vs Aluminum Wheel Stiffness

Carbon fiber wheels are stiffer than aluminum wheels. This is because carbon fiber is up to 5 times stiffer than aluminum at the same thickness. Engineers can further improve carbon fiber wheel stiffness by manipulating the orientation of the fibers and the layup. This allows manufacturers to build incredibly stiff carbon wheels that don’t flex under stress. To read more about the stiffness of carbon fiber and aluminum, check out this interesting article.

Benefits of Stiff Wheels

Stiffer carbon fiber wheels are preferable for a number of reasons. First, they make the bike feel more responsive to pedaling and steering inputs. You can accelerate and steer faster when your wheels are stiff. Stiff wheels also respond better to the features of the surface you’re riding. Handling is more predictable. The bike will also feel more lively and responsive when the wheels are stiff.

Stiffer wheels also allow you to steer more precisely and maintain your line better while cornering. They track well while leaning the bike and cornering hard. This is because the wheels won’t flex and send you down an unpredictable path. The steering feels crisp. This is important while riding through technical sections of trail or at high speeds. 

Stiffer wheels also allow you to maintain more speed because less energy is lost to wheel flex. When you hit a bump or an obstacle in the road or trail, stiff wheels deflect more predictably.

All of this inspires confidence, allowing you to ride faster and more aggressively. You can push into a corner and speed out the other side. Many racers prefer carbon wheels for these reasons. 

Aluminum wheels, on the other hand, can flex a bit when cornering or hitting an obstacle. For heavier riders, the flex can be noticeable. If your wheels are too flexible, your bike won’t be able to corner as quickly or predictably. The bike may also ride a bit less efficiently. Some energy gets lost to wheel flex. The bike also won’t feel quite as responsive. This can slow you down. 

There are some incredibly stiff aluminum wheels on the market these days. To improve the stiffness of aluminum wheels, some manufacturers use proprietary oversized spokes, extra spokes, or a unique spoke pattern. These designs result in aluminum wheels that are almost as stiff as carbon fiber wheels. The aluminum alloy used, rim cross-section shape, and wall thickness also all play a role in wheel stiffness. 

A mountain biker riding down a steep trail.
Stiff wheels make the bike more responsive to steering inputs.

Drawbacks of Stiff Wheels

It is possible for bike wheels to be too stiff. This was a problem with early carbon fiber wheels. Overly stiff wheels can be uncomfortable to ride because they transmit bumps and vibrations from the road or trail into your body. This is particularly noticeable while riding rough roads or off-road. The ride feels harsh and chattery. 

Some long-distance off-road riders prefer aluminum wheels because they offer a more comfortable ride. The wheels can absorb some bumps. A bit of wheel flex can improve ride quality. 

Another drawback to stiff wheels is that traction can suffer. Stiff wheels can’t conform to the ground as well as more flexible aluminum wheels. On particularly rough or bumpy surfaces, stiff wheels tend to skip around. Your tires don’t stay on the ground quite as well. This reduces friction between your tires and the ground, making it easier to lose traction. You can make up for this by reducing your tire pressure by a couple of PSI. A good suspension system also helps.

A mountain biker riding down a bumpy trail
Stiff carbon wheels can feel harsh on rough terrain.

Choosing Wheels Based on Stiffness

These days, many carbon fiber wheel manufacturers optimize their wheels for comfort and ride quality along with stiffness. Manufactures can engineer carbon fiber wheels to be stiff in one direction but more compliant in another. Ideally, the wheel should be laterally stiff but vertically compliant.

Modern carbon wheels are often designed to be laterally stiff so they maintain their performance advantages in terms of cornering and responsiveness. At the same time, they are designed to have some vertical flex. This allows the wheel to absorb some shocks and vibrations while riding rough terrain. Carbon fiber also has natural vibration absorption qualities due to its low density.

Manufacturers are able to fine-tune the stiffness of carbon fiber wheels. They can manipulate the direction of the fibers, the thickness of the layers, or the type of fibers or resin used to optimize the wheels for stiffness, performance, and comfort. Modern carbon fiber wheels often offer better performance and more comfort than comparable aluminum wheels. 

Other interesting designs are also possible with carbon fiber wheels. For example, these Zipp wheels feature a single wall carbon rim that can flex from side to side relative to the spokes. They call this design ‘ankle compliance’ because the wheel can adapt to uneven terrain like a human ankle.

This design allows the rim to rotate side to side with the tire so the rim stays parallel with the ground while cornering. This increases traction. The rim can also twist at the contact point during impacts. This allows the tire to better conform to the ground. It also reduces the likelihood of pinch flats because the tire hits obstacles more directly instead of near the bead. These wheels are also designed to have plenty of vertical compliance for a smooth and comfy ride.

These carbon wheels are designed specifically for enduro and trail riding. They are more flexible than any aluminum rims.

Winner: Carbon fiber wheels can be stiffer than aluminum. This improves efficiency and cornering performance. Aluminum rims are often more compliant. This increases comfort.

Wheel Durability

Aluminum wheels are more durable than carbon fiber. You wouldn’t expect this to be the case because carbon fiber is the stronger material. After all, it has a much higher strength-to-weight ratio. Carbon wheels are less durable because the material is more brittle. This makes it much easier to crack a carbon fiber rim. Aluminum rims can handle a much harder impact force without sustaining damage. 

Carbon Rim Durability

The most common way for a carbon rim to get damaged is from a rim strike. There are two types of rim strikes. A rock, root, or some type of debris can hit the side of the rim and crack it. The tire can also bottom out when hitting a bump or landing from a jump and the impact force can crack the rim. Rim strikes are most common ways for carbon rims to fail. 

A hard rim strike can crack a carbon rim. A cracked carbon rim is structurally compromised and usually cannot be repaired. It should be replaced as soon as possible for safety reasons. A damaged carbon rim can fail at any time without warning. 

These types of rim failure are most common in mountain biking. Particularly in downhill and enduro mountain biking where riders race at high speeds on gnarly terrain. This type of riding generates a large amount of force. A particularly hard landing can destroy a carbon rim. 

Carbon rim damage is also common in gravel riding and cyclocross. Rocks and other debris can get kicked up from the trail and hit the sides of the rim. Over time, this weakens the rim. In rare cases, a hard impact can crack the rim. Sometimes you just get unlucky. 

For this reason, carbon wheels may not be ideal for those who are hard on their rims and those who ride rocky technical trails or loose surfaces. 

Carbon rims are least likely to get damaged while road riding because there is less debris that can hit the rim. Many road cyclists get tens of thousands of miles out of a set of carbon fiber rims. 

Carbon rims can break crack just like this carbon frame. Image: “Broken Carbon Fiber Frame” by Michael Mandiberg, licensed under CC BY-SA 2.0

Aluminum Rim Durability

Generally, aluminum rims can handle harder impact forces than carbon fiber rims without cracking or breaking. If a rock strikes an aluminum rim, it might cause some scratching or even a small dent. Most of the time, this damage is only cosmetic. Aluminum rims remain perfectly usable, even when they’re severely scratched up. 

Aluminum rims can also handle harder impact forces without cracking. Instead, the rim will dent, deform, or flat spot. In most cases, it is still possible to ride a damaged aluminum rim, at least temporarily. 

For this reason, many who ride in cycling disciplines where rim damage is common, like some forms of mountain biking, prefer aluminum rims. They can take more of a beating without failing. 

This allows riders to attempt more challenging trails without having to stress as much about damaging a rim. It’s also easier on the budget if you do need to replace an aluminum rim. Some mountain bikers treat their rims like they’re disposable. 

Cosmetic scratching and dents on aluminum rims can cause some issues. For example, if you run tubeless tires, a dent near the bead can compromise the tubeless seal. In this case, you may need to attempt a repair or replace the rim if you want to continue riding tubeless. If you use rim brakes, scratching or warping on the rim walls can cause issues with brake performance. Most mountain bikers use disc brakes these days so rim scratching is rarely an issue.

Carbon and Aluminum Rim Failure

A particularly hard impact can destroy any rim. Carbon and aluminum rims fail in different ways. During a hard impact, an aluminum rim can dent. A flat spot can form. A hard hit can even bend an aluminum rim. A carbon rim, on the other hand, will almost always crack. Because carbon is brittle, it can’t bend, deform, or dent the way an aluminum rim can. 

If an aluminum rim fails catastrophically, it’s much more affordable to replace than a carbon fiber rim. This is an important consideration for mountain bikers who are hard on their rims. Most of us can’t afford to regularly shell out thousands of dollars on replacement carbon wheels. 

Catastrophic failure is less common with aluminum rims. In many cases, a severely damaged aluminum rim still remains ridable, at least for a short while.

For example, on my first bike tour, my friend hit a gravel patch during a fast descent and took a spill. Luckily, he was fine but his bike took a beating. The rear aluminum rim was badly bent. Miraculously, he was able to ride about 100 miles home on the bent rim. I highly doubt a carbon fiber rim would have survived the same crash. 

In some cases, damaged aluminum rims can be repaired. It is possible to bend a deformed rim back into shape. Sometimes you can hammer out small dents. For example, when my friend arrived back home with his bent aluminum rim, he was able to bend the wheel back into shape and true it up. It was never perfect but it was usable. 

You generally can’t repair a carbon fiber rim after it cracks. There are some exceptions to this. I’ll talk more about rim repairability later on. 

Many mountain bikers do not buy carbon fiber rims because they believe them to be too fragile. The reason is that many cyclists have experienced carbon rim failure. This was common when the technology was new.

Modern carbon fiber rims are much more durable than they were in the past. Carbon fiber technology and construction techniques have improved greatly over the years. Most recreational riders have no issues with durability these days.

There is a way to improve the durability of carbon fiber wheels. You can install tire inserts. These are pieces of foam that you place between the rim and tire. The insert fills around half of the volume of your tire. This protects your carbon rim from hard hits. This makes rim failure less likely during a hard landing or while hitting an obstacle in the trail. 

The drawback is that tire inserts add a considerable amount of weight. This can defeat the purpose of riding lightweight carbon wheels in the first place For more info, check out this guide to tire inserts.  

Another consideration is the warranty. Some manufacturers offer no questions asked lifetime warranties on their high-end carbon fiber rims. Knowing you could get a replacement if a rim cracks brings some peace of mind. 

Generally, it’s best to ride wheels that you can afford to replace if they get destroyed. For many riders, that means riding aluminum rims. 

It’s also important to keep in mind that there are many riders who have put tens of thousands of miles on their carbon rims without any issues. If you’re the type of rider who is easy on your gear, rides smoothly, and uses a tire insert, you probably won’t run into any durability issues with carbon rims.

Some competitive cyclists own both a set of aluminum and carbon rims. They ride the aluminum rims while training then swap them out for carbon rims for race days or special occasions. 

Winner: Aluminum wheels are more durable than carbon fiber.

Carbon Vs Aluminum Wheel Cost

Carbon fiber wheels are significantly more expensive than aluminum wheels. In fact, they are often double the price. A set of carbon fiber wheels costs $1500-$2500. To compare, a high-end set of aluminum wheels costs around $600-$1500. On average, carbon fiber wheels cost about $1000 more than comparable aluminum wheels.

The lower price is the reason that the vast majority of new bikes are sold with aluminum rims. It brings bike prices down considerably. Most cyclists don’t want to pay an extra $1000 for wheels. 

Entry-level to mid-range aluminum wheels are even cheaper. You can buy a basic aluminum wheelset for $150-$300. If you’re on a tight budget, carbon fiber wheels aren’t even an option. 

A flat bar road bike on a bike trail
Most bikes come with aluminum rims. Carbon fiber rims are usually an aftermarket part.

Aluminum wheels are cheaper because they are much easier to manufacture. The raw aluminum is extruded into a long, straight piece of rim. These are cut to length, bent into a circle, then welded or pinned together. 

The process of aluminum manufacturing has been refined for decades. Much of it can be automated with modern machinery. Aluminum rims can be mass-produced. A productive factory could output thousands of aluminum rims per day. It takes far fewer man-hours to make an aluminum rim. The raw materials used to make aluminum rims are also much less expensive. Aluminum is cheaper than carbon fiber. 

Carbon fiber rims are much more expensive to make. The main reason is that the manufacturing process is more labor-intensive. It takes more man-hours to build each carbon rim because much of the work must be done by hand. It can’t be automated. The labor involved requires skill. Workers must lay carbon fiber sheets into molds in the proper order and direction. The process requires know-how and precision.

The tools and raw materials required to build carbon fiber frames are also more expensive. For example, building with carbon fiber requires custom molds. These carbon fiber molds are extremely expensive to produce. The carbon fiber sheets are costly as well. Special ovens are needed to harden the wheels. The rims must also be built in a climate-controlled facility. This also increases costs. 

To meet lower price points, some manufacturers use a lower grade of carbon fiber that contains more fillers and resin. These wheels are heavier and less reliable. They may not offer any benefits over aluminum. They can be dangerous as well. If you’re on a tight budget, it’s best to stay away from carbon fiber rims. 

Another expense to consider when deciding between carbon fiber and aluminum rims is replacement cost. If you crash your bike or land too hard from a jump, you could destroy your rim. It’s much cheaper to replace an aluminum rim than carbon fiber. Replacing a bent aluminum rim might cost you a few hundred dollars. Replacing a cracked carbon fiber rim could cost you over $1000.

The lower price of aluminum rims makes them an excellent choice for cyclists who are hard on their rims and those who ride in cycling disciplines where accidents are common, such as downhill mountain biking. 

You’ll also want to consider the other wheel components you’re going to use when deciding between carbon or aluminum rims. The hubs, spokes, and tires all play a role in the performance and ride quality of the finished wheel.

If you’re buying high-end carbon rims, you won’t want to cheap out on your hubs, for example. This adds to the cost. If you use rim brakes with your carbon wheels, you need to buy special carbon compatible brake pads. This adds to the cost as well. One way to save money on carbon rims is to buy second-hand. Aluminum wheel components can be cheaper.

Winner: Aluminum wheels cost half as much as carbon fiber wheels. You could save over $1000 by riding aluminum rims.

Comfort

Many cyclists find that aluminum wheels offer a more comfortable ride than carbon fiber wheels. The reason is that aluminum does a better job of absorbing shocks and vibrations from the road.

This is possible because aluminum is a bit more compliant than carbon fiber. It can flex a bit to absorb bumps. That said, modern carbon fiber wheels are almost as comfortable. 

Ideally, you want your wheels to be stiff laterally so they track well while taking hard corners and riding rough terrain. This allows you to steer predictably and maintain your line. At the same time, you want your wheels to have some vertical compliance. This allows the wheel to help absorb some shocks and vibrations, making the ride more comfortable while riding over rough surfaces.

In the past, carbon fiber wheels were designed to be as stiff as possible. This was great for efficiency and handling. The drawback was that the excessive stiffness made the ride quality too harsh. The rigid wheels would transmit shocks and vibrations through the wheels and into your body. This made for a rough and chattery ride that many cyclists did not enjoy. 

Two cyclists riding down a dirt road

Modern carbon fiber wheels are designed with comfort and ride quality in mind. They are designed to be stiff laterally but flexible vertically. This is achieved by fine-tuning the carbon fiber during the manufacturing process.

Manufacturers can vary the direction of the fibers, type of resin and filaments, the thickness of the fibers, density, and more to achieve the desired vertical compliance and lateral rigidity. Carbon fiber naturally offers excellent vibration absorption qualities due to its low density. This improves comfort as well. 

In reality, the wheel material only plays a small role in the overall comfort of the bicycle. In fact, most riders probably wouldn’t be able to even feel the difference between carbon fiber and aluminum wheels, in terms of comfort. The tires, grips, saddle, suspension system, and frame play a much bigger role in comfort.

For example, wide, high-volume tires with lower air pressure can absorb far more shocks than any wheel could. A well-fitting saddle and quality grips can make a big difference in comfort as well. The frame material and geometry are important considerations as well. A suspension system can greatly improve comfort by absorbing large shocks. 

Winner: Aluminum wheels offer a more comfortable ride.

Rim Repairability

Both aluminum and carbon fiber rims can be repaired in some cases. Generally, aluminum rims are more repairable than carbon fiber rims. 

If an aluminum rim gets dented from hitting a rock, pothole, curb, etc, it is possible to bend it back into shape in most cases. Check out this guide for instructions. The process involves using a wrench to pry the dent out.

You’ll really only want to attempt this repair if the dent affects some function of the wheel. For example, maybe the dent prevents your tubeless tires from sealing with the rim. Maybe the dent causes your rim brakes to rub. In these cases, it may be worth trying to fix the rim. 

It’s important to keep in mind that bending an aluminum rim back into shape can weaken the rim. If the rim still functions normally with a dent, leave it as is. 

Aluminum rims can also crack. This is usually caused by fatigue. All rims crack when they reach the end of their life. Most cracks form near the spoke holes. A crack could also be caused by a hard impact. It is possible to repair some aluminum rim cracks. The process involves welding the crack then machining it down so it’s smooth. 

Repairing cracked aluminum rims is usually not cost-effective. A professional welder might charge $300 to repair a cracked aluminum rim . In that case, you’re better off just buying a new rim for $300. You never know how long a repair will last or if another crack will form. It’s difficult to determine the structural integrity of aluminum that has cracked. Aluminum rims that have been repaired may not be safe to ride. 

An aluminum bike rim

Carbon fiber rims, on the other hand, are usually not repairable. If the rim cracks, it should be replaced. You never know when it will fail catastrophically and send you to the ground. 

That said, there are some companies that will repair some type of cracks on carbon fiber rims. For example, this company claims that they can repair a crack on any part of a carbon rim except for the brake track on a rim brake wheel, the spoke hole areas, and the bead.

Of course, carbon fiber wheel repair is expensive. It’s risky to pay for an expensive repair, not knowing if the repair will hold or how long it will last. In most cases, you’re better off just buying a new rim. 

Some riders attempt repairs on their own. For example, they will fill a small crack with super glue or make a patch from a piece of carbon fiber and epoxy. This isn’t recommended but it is something that people do. I wouldn’t want to risk this. 

Tip: Many manufacturers guarantee their rims for a certain amount of time. If your rim cracks, you may be able to get it replaced for free under the factory warranty. Be sure to check your warranty before you go out and buy a new rim. 

Winner: Aluminum rims are easier to repair. Carbon fiber rims usually can’t be repaired. 

Rim Longevity

In theory, carbon fiber wheels should last longer than aluminum wheels because carbon fiber doesn’t fatigue as quickly. As long as you ride smoothly, avoid rim strikes, and don’t allow your tires to bottom out, your carbon rims should last pretty much indefinitely. Many road riders get tens of thousands of miles out of a quality set of carbon rims.  

The problem is that carbon fiber rims are more fragile than aluminum because the material is more brittle. A carbon rim can’t handle as hard of an impact without cracking. 

If you ride in a cycling discipline that is demanding on rims, such as mountain biking, there is a good chance that your carbon rim will hit something, crack, and fail prematurely. Sometimes a rock can get kicked up and destroy a rim. You might just get unlucky. For this reason, carbon fiber rims usually don’t last as long as aluminum. Aluminum rims can take more of a beating without cracking or failing. 

A vintage road bike with aluminum rims
Aluminum rims can last for decades. It’s common to find vintage bikes with the original aluminum rims.

Aluminum rims do fatigue over time. This is because aluminum doesn’t have a fatigue limit. Every time you apply stress to your rims, the aluminum slowly weakens. After enough miles, a crack will inevitably form. No rims last forever. 

Exactly how long your aluminum rims will last depends on a number of factors including the type of riding you do, the cross-section shape of the rime, the wall thickness, your weight, how you treat your rims, the type of brakes you use, the size of the wheels, the quality of the material, and more. A quality set of aluminum rims could last anywhere from 5,000-35,000+ miles.   

Winner: Under real-world use, aluminum rims usually last longer than carbon fiber rims.

Safety: Rim Overheating and Failure

Carbon fiber rims can be more dangerous than aluminum rims. The reason is that carbon rims can overheat and fail under extreme conditions. This problem is mostly limited to carbon fiber clincher wheels that are paired with rim brakes. 

Friction caused by rim brake pads rubbing against the carbon fiber rims creates heat. Carbon fiber does a poor job of dissipating heat compared to aluminum because the material is a poor thermal conductor. 

During a long descent, heat builds up in the rims and softens the resin that bonds the carbon fiber together. If the resin gets soft enough, the rim can begin to bubble or fold open. Heat can also cause the inner tube to burst and blow the tire completely off the rim.

This was proven in brake testing performed by Alto Cycling. They tested carbon fiber clincher wheels from a number of brands by running them at 1200 watts with a 7 pound load. The wheels were run until they failed. Heat buildup was measured. Some wheels failed in just 300 seconds while others lasted over 1200 seconds. It’s important to note that some brands responded by defending their wheels and criticizing the way that the testing was performed.    

As you can imagine, this type of failure could be pretty dangerous. Imagine speeding down a hill at 30 mph when your rim decides to fail catastrophically and buckle under you. This could cause a serious injury. 

Even though this type of failure is rare, it became common enough that carbon fiber clincher wheels have been banned or discouraged at some cycling events that include long steep descents. 

Heat failure was more common on carbon fiber rims in the past because the resins used at the time were more sensitive to heat. Modern resins are much more resistant to overheating. That said, carbon fiber clincher rims can still overheat in extreme conditions. If you ride long steep descents, you might want to avoid carbon rims for safety reasons. 

Overheating can happen with aluminum rims as well. The difference is that it’s much less likely because aluminum is an excellent thermal conductor. It dissipates heat much more quickly and efficiently than carbon fiber. 

Aluminum rims also don’t usually fail when they overheat. Instead, the heat causes the air pressure in the tire to increase. Eventually, the tire will fail and a sidewall will blow out. This type of failure is less catastrophic and less common. Of course, it could still be dangerous. You could easily crash if a tire blows out. 

There are a couple of techniques you can use to avoid overheating your rim. You can descend faster and brake less. Less heat builds up this way. Another trick is to brake hard and slow way down then let off the brakes for a while while you speed back up. This gives your rims a chance to cool. You can also try alternating between using the front and rear brakes.

If you believe your rims are beginning to overheat, you can stop mid-descent and let them cool down for a few minutes before continuing on. I do this occasionally while touring. You can also use disc brakes. This way, you don’t have to worry about rim damage from overheating. Keep in mind that disc brakes can overheat too. 

Cracked rims can also be a safety issue, regardless of the material. It’s never safe to ride a cracked rim. Cracked rims can fail catastrophically at any time, causing you to crash. 

A mountain biker riding down a gravel hill.
Rims can overheat and fail during long, steep descents.

To be safe, you should periodically inspect your rims. Look closely near the spoke holes and on the sidewalls. These are the most common areas for cracks to form. If you spot a crack, you should replace the rim as soon as possible. 

This is necessary because it is impossible to determine the structural integrity of a cracked rim. Cracks also expand over time. If you ride a cracked rim long enough, it will eventually fail. You just never know when. 

Winner: Aluminum wheels can be safer when riding in extreme conditions. They are less likely to overheat. 

Which Wheel Material is More Environmentally Friendly? Carbon Vs Aluminum

Most cyclists care deeply about the environment. For some of us, it’s the reason we ride a bike instead of drive a car. One excellent feature of aluminum is that the material is incredibly recyclable. For this reason, aluminum wheels are more environmentally friendly than carbon fiber.  

Aluminum is one of the most recyclable materials available. According to this article from Aluminum.org, aluminum is 100% recyclable and 75% of all aluminum ever produced in the US is still in use. The material can be infinitely recycled. After your aluminum rims wear out, they can be melted down and recycled into an endless number of new products including soda cans, building materials, or even new bike wheels.

Carbon fiber, on the other hand, is not as recyclable. When your carbon fiber wheels reach the end of their life, they will end up in a landfill where they may sit for centuries. Carbon fiber can’t simply be melted down and reused like aluminum and other metals. This makes the material less environmentally friendly. 

Carbon fiber can be partially recycled. The process involves burning away the resin so the filaments can be reused. The resin is basically a type of plastic. As you can imagine, this process isn’t very good for the environment. Large pieces can sometimes be repurposed into other products. A company called Carbondale recently released a new type of carbon wheels that are supposed to be 100% recyclable. For more info, check out this article.

Winner: Aluminum wheels are more environmentally friendly than carbon fiber. 

Speed and Efficiency

Carbon fiber wheels are more efficient than aluminum. The increased efficiency allows you to travel further while burning less energy than you would while riding aluminum rims. Carbon rims also allow you to maintain a higher average speed.

Carbon fiber wheels are more efficient for 3 main reasons. First, carbon wheels are lighter. It takes less energy to accelerate, climb, and maintain your speed with a lighter bike. This is because you’re simply moving less weight around. When riding heavier aluminum wheels, you’ll tire out a bit faster due to the extra weight. The lighter wheels also stop faster. This allows you to start braking a bit later when going into a corner. This saves you time. 

The second reason carbon wheels are more efficient is that they are stiffer. When you accelerate hard, your wheels want to flex from side to side as you rock the bike from left to right. When this happens, some of your energy is being wasted flexing the rims instead of driving you forward. Wheels can also flex during a hard corner, slowing you down. When your wheels flex, you’ll have to spend more energy to pedal back up to speed. On some frames, the rims can flex enough that the rim rubs against the brake pad. This costs you more power. 

Carbon fiber rims are designed to be laterally stiff so they flex less as you pedal. Because carbon fiber wheels are stiffer, you lose less energy to wheel flex. 

This allows you to use your energy more efficiently because you’re not wasting energy flexing the rims. The bike will maintain its speed better when you’re not pedaling as well. This allows you to ride slightly faster and maintain a higher average speed. 

A road race
For competitive riding, efficient rims are crucial

Aluminum rims tend to have a bit more lateral flex. This wastes energy that could have been used to drive you forward. For more info on wheel flex, check out this in-depth article.

The third reason that carbon fiber rims are more efficient is that they tend to be more aerodynamic. Carbon fiber wheels can be made into more aerodynamic shapes while maintaining their light weight.

This is possible because carbon fiber is a less restrictive material than aluminum. It can be molded into any shape. Carbon fiber is also much lighter than aluminum. Manufacturers can use more material and maintain the light weight.

Aerodynamic rims are deeper so the hole in the middle is smaller. This design reduces drag. Deeper rims create less wind resistance because the hole in the center of the rim is smaller. This allows the wheel to cut through the air more easily because there is less wind resistance acting against you while you ride. I’ll talk more in-depth about aerodynamics and rim shape in a later section. 

This can save a considerable amount of energy. Whether or not aerodynamics matter depends on your speed. At lower speeds, aerodynamics don’t make much of a difference. At speeds above around 9 mph (16 kph), aerodynamics are important because wind resistance becomes the main force acting against you. 

Each of these above efficiency gains is minimal on its own. When you add them all together, the difference can be significant. Of course, efficiency and speed really only matter for competitive riders. Recreational riders may not even notice the difference. Both carbon fiber and aluminum can make incredibly lightweight, stiff, and aerodynamic wheelsets. 

The rims aren’t the only component that controls wheel efficiency and speed. The number of spokes, type of spokes, spoke thickness, axle diameter, frame material and design, rim width and depth, hub type, and more all play a role in wheel stiffness and efficiency. 

Winner: Carbon fiber wheels are faster and more efficient than aluminum.

Ride Quality: Performance and Comfort

There is no clear definition of bicycle ride quality. This article does a good job of explaining ride quality and various aspects that may affect it. To me, ride quality is the combination of the performance and comfort of a bicycle. 

When building wheels, manufacturers have to strike a compromise between performance and comfort. The wheel needs to be stiff laterally so the bike can handle responsively and predictably, accelerate quickly, and ride efficiently. At the same time, the wheel needs to have a bit of vertical compliance so the ride doesn’t feel too harsh and so traction doesn’t suffer. The wheel material, design, and weight all play a role in ride quality. 

For example, when you take a hard corner, you want the bike to maintain its line without the wheel flexing and sending you down an unpredictable path. At the same time, you also don’t want the wheel to flex and waste energy. When you hit a pothole, you don’t want your teeth to shake out of your head because the ride is so harsh. You also don’t want the wheel skipping around on bumpy surfaces.

There is no clear winner when it comes to ride quality. These days, many riders argue that carbon fiber wheels make the best compromise between performance and comfort. Carbon fiber allows manufacturers to engineer and fine-tune wheels with incredible precision. 

For example, with modern layering techniques, computer modeling, and high-tech resins and fibers, manufacturers can build carbon wheels that offer excellent performance while maintaining a comfortable ride. They can be stiff laterally and pliable vertically. Carbon fiber also offers excellent vibration absorption qualities due to its low density. This can help greatly to improve comfort. Carbon fiber wheels can also be built with more precision than aluminum. Tolerances are lower. All of these factors help to improve ride quality. 

In the past, this wasn’t the case. The first carbon fiber wheels were optimized for performance. They were made incredibly stiff. While these stiff wheels performed well in terms of handling and efficiency, some riders found them to be too harsh.

Ride quality is somewhat subjective. Many riders find that aluminum wheels offer better ride quality. They find that the wheels offer a bit more flex, which can improve comfort. Quality aluminum wheels can offer a good amount of stiffness as well. 

Of course, the wheels only play one role in the overall ride quality of a given bicycle. You’ll also want to consider the frame material, frame geometry, handlebars, suspension system, saddle, peddles, grips, and tires. That said, the wheels are one of the more important components controlling ride quality. 

Winner: Carbon fiber wheels offer better ride quality.

Tire Pressure

You can run low-pressure tires on both aluminum and carbon fiber wheels. You can get away with running your tires at lower pressures if you go with aluminum rims. This is possible because you’re less likely to cause damage if you bottom out and a rim strike occurs. You may feel more comfortable running your tires at lower pressure for this reason. 

If you want to run your carbon fiber rims at low pressure, consider installing tire inserts. These foam rings protect your wheels from getting damaged in the event of a rim strike. They add a bit of weight but can save your wheels. To me, inserts are worth it for peace of mind.

These Tannus Armour Tubeless Tire Inserts would work well. They protect your rims from damage, prevent pinch flats, dampen vibrations, and reduce the likelihood of burping air from tubeless tires. The inserts weigh only 150 grams.

The main benefit of riding with your tires at a lower pressure is that it improves traction. This is possible because the softer tire can deform more at the contact patch. This allows more of the tread to contact the ground, which increases friction. Lower tire pressure also increases comfort because the softer tires can absorb more bumps. 

Both carbon and aluminum rims are suitable for high-pressure road tires. They can handle the pressure without any issues. 

Winner: Aluminum wheels are better for those who like to run their tires at low pressure because damage is less likely in the event of a rim strike. 

Which Wheels Stay True Longer? Carbon Fiber or Aluminum

Bicycle wheels require very little maintenance. Really, all you have to do is keep the hub bearings greased and true the wheels once in a while to make sure the rims stay straight and round. Truing bike wheels involves adjusting the spoke tension. For more info, check out this guide.

Carbon fiber wheels tend to stay true longer than aluminum wheels. You may only have to true your carbon wheels once after 25,000 miles. You may have to check the spoke tension and true your aluminum wheels once every 10,000 miles.

I’m not exactly sure why carbon rims stay true longer. It may have something to do with the higher rigidity of the rims. It could be because aluminum rims can flex more and permanently deform. Another theory I have read is that carbon fiber rims are more precisely made at the factory. They are rounder and flatter than aluminum rims because tolerances are lower. Aluminum rims can be slightly less flat or round. This makes it harder to get spoke tension even around the wheel. As a result, the aluminum wheels can go out of true more easily. Whatever the case, carbon wheels rarely go out of true.

Exactly how often you’ll have to true your wheels depends on a number of factors including your weight, the type of terrain you ride, and the quality of your wheels. Your wheels may need to be trued more frequently if you’re a heavy rider or if you ride rough terrain. High-quality, hand-built carbon fiber wheels may only need to be trued once when they’re built. Low quality or poorly built wheels may need to be trued after just a few thousand miles. 

Winner: Carbon fiber wheels stay true longer than aluminum. This advantage is minor because both carbon and aluminum wheels stay true for many thousands of miles when properly built. 

Rim Width

Across pretty much all disciplines of cycling, wider tires are becoming more popular. As a result, rims are becoming wider as well. The most common measurement for rim width is called ‘internal rim width’. This is the distance between the inside walls of the flanges where the tire meets the rim. Rim width is a compromise. There are benefits and drawbacks to using wider rims and narrow rims. 

Rim Width for Off-Road Riding

The main benefit of using wider rims is that they provide more support for the sidewalls of the tires. This reduces the amount that the tires can roll on the rim as you corner. In other words, the tire won’t try to fold to the sidewall on the rim. This improves traction and cornering performance by stabilizing the tire on the rim. 

In addition, wider rims can improve traction by allowing more tread to contact the ground. The tire’s side knobs can more easily bite into the ground while cornering hard. Tubeless tires will also be less likely to separate from the rim and burp air and sealant.

Wider rims also allow you to run your tires at lower air pressure. The wider tires that are typically paired with wider rims have a greater volume. High-volume tires can be run at lower pressures. These tires are less likely to bottom out and hit the rim when they hit an obstacle. This is the case because there is more air in the tire to act as cushioning. Wider tires are also taller. This means the tire would have to compress further to hit the rim.

A fat bike with wide carbon rims
A fat bike with extra-wide rims

There are a couple of benefits to running wider, higher volume tires with lower air pressure. Wider rims can better support the sidewalls of the tire at lower pressure than narrow rims. This improves traction. Higher volume tires can also absorb larger bumps, which improves comfort. The tires are less likely to bottom out and hit the rim.

Running your tires at lower pressure also increases traction. This is because the tire can deform more at the contact patch so more tread contacts the ground. Side knobs can bite. This increases the friction between the tire and the ground. With more traction, you can corner and accelerate harder without your tire sliding out. 

For these reasons, wider rims are ideal for off-road riding, gravel riding, and mountain biking. The increased sidewall support and ability to run the tires at lower pressure greatly increase traction and comfort. With wider tires, you can corner faster without worrying about your tire folding on the sidewall, sliding out, or separating from the rim and burping air. 

Running wider rims and tires can also reduce the likelihood of rim damage while riding carbon fiber rims because rim strikes are less common with wide, high-volume tires. Wider rims are also a bit thicker and structurally stronger. 

Wider rims can also benefit road cyclists for the same reasons. The benefits of wider rims will be less significant because road bike road tires are run at higher pressures. Traction is less of an issue as well on pavement.  

Rim Width for Road Riding

Road riders can also benefit from riding wider rims. There are fewer benefits because road riders tend to run their tires at higher pressures. Less traction is also required for road riding. 

In road cycling, the external rim width is more important than the internal rim width. External rim width is the distance from the outside of one rim wall to the outside of the opposite rim wall. 

This measurement is important due to aerodynamics. In road cycling, aerodynamics matter far more due to the higher speeds. At speeds over 10 mph, wind resistance creates a significant amount of drag. You have to burn more energy to overcome that extra resistance. 

A number of studies have been performed on the aerodynamics of road bikes. Based on wind tunnel testing, the rule of 105 was formed. According to this interesting article, “The Rule of 105 states that the rim must be at least 105% the width of the tire if you have any chance of re-capturing airflow from the tire and controlling it or smoothing it.” In other words, the rim should be 5% wider than the tire so the tire and rim minimize disruption of the air as they pass through. 

For example, if you run 23mm tires, you’d want your external rim width to measure 24.15mm at a minimum (23mm x 105% = 24.15mm). If you run 25mm tires, you’ll want to run rims that measure at least 26.25mm. Following the rule of 105 when choosing rims and tires for your road bike will improve aerodynamics and efficiency. 

A road bike with narrow rims

Whether you ride a road bike or mountain bike, it is possible for your rims to be too wide for your tires. There are several reasons for this. Most importantly, it’s easier to damage a rim when the rim wall sticks out further than the sides of the tire. The bulbous sides of the tires act as bumpers for the rim walls to protect them from impacts from obstacles on the road or trail. You really want to avoid overly wide carbon fiber rims because they will be much easier to damage. Next, wider rims can spread narrow tires open too far and square off the tread. This can hurt your handling and tire performance. If you ride wide rims, you’ll want to ride wider tires to avoid this. You want your tires to maintain their rounded shape. Wider rims will also be heavier simply because they have more material. 

Rim width is a compromise. You want your rims to provide good tire support and protection while still being lightweight and efficient. When choosing rims, you’ll want to think about the tire width you want to ride, the tire pressure, and the terrain you ride.

You’ll also need to consider your frame clearance when choosing rims. Your maximum tire width will be limited by your frame. You’ll need to choose rims that are narrow enough that the tires won’t rub your frame. 

Every rim can support a range of tire widths. For example, road rims with an internal width of 19-23mm could support 25-35mm wide tires. Mountain bike rims with an internal rim width of 30-35mm could support 2.4-2.8” wide tires. If your tires and rims are within a couple of millimeters of the ideal parameters, you shouldn’t have any issues.

If you’re not sure whether or not a specific tire will fit on your rims, check with the rim manufacturer. Most list a range of compatible tire widths. 

Winner: If you’re choosing wide rims, carbon fiber is the better material because it is lighter.

Aerodynamics and Rim Depth

According to this interesting article, when riding at speeds over 9mph (around 15 kph), air resistance becomes the main force acting against you while cycling. Once you reach 30mph, 90% of your energy goes toward overcoming air resistance.  

Air resistance is the reason that road cyclists ride in groups, drafting behind one another. It’s the reason cyclists who ride in timed events work to make their bike and their body as aerodynamic as possible. When you watch a cyclist sprint, you’ll notice that they’re tucked as far down as possible and riding in the drops. The purpose of this is to increase aerodynamics to reduce drag.

The more aerodynamic a bicycle is, the faster and more efficiently you can ride. The reason is that you waste less energy overcoming wind resistance. More energy goes toward driving you forward. 

The wheels play a major role in the overall aerodynamics of a bicycle. Wheel aerodynamics are particularly important on road bikes because road cyclists ride at high speeds than mountain bikers. The faster you ride, the more aerodynamics matter.

Rim Depth

A number of factors determine the aerodynamics of a bike wheel. The rim shape, rim width, rim depth, spoke shape, and rim surface texture all play a role. The tire width and tread pattern also come into play. Probably the most important factor to consider when choosing wheels is the rim depth. 

Generally, deeper rims are more aerodynamic than shallow rims. The reason is that deeper rims reduce air separation across the wheel’s surface. The air stays attached longer as it flows past the wheel. In other words, a wheel with deep rims disturbs the air less as you ride through it.

This is possible because the hole in the center of the wheel is smaller when the rims are deeper. This allows the wheel to cut through the air more smoothly.

Cyclists who are trying to maximize wheel aerodynamics choose the deepest rimed wheels they can get. Some cyclists use aero disc rear wheels. These have a solid plate that completely covers the hole in the wheel. These wheels are popular among triathlon and time trial riders. 

Deep aero rims on a single-speed bike

For those who ride at lower speeds, such as mountain bikers, wheel aerodynamics matter less. As mentioned earlier, at speeds below around 9mph, wheel aerodynamics don’t really matter. 

Rim Weight Vs Aerodynamics

There are some drawbacks to using deep, aerodynamic rims. The main one being weight. Deeper rims are heavier because they require more material to make. This is where the weight difference between carbon fiber and aluminum wheels comes into play. 

Because carbon fiber is so much lighter than aluminum, it is possible to make deep carbon rims that are still lightweight, even though deep rims contain more material. Deep aluminum rims are significantly heavier. 

Carbon aero rims might weigh 300-500 grams less than comparable aluminum aero rims. For this reason, you’re much better going with carbon rims if you’re trying to optimize your bike for aerodynamics.

Carbon aero rims are also easier to manufacture due to the strength of the material. Aluminum rims can’t be made as deep as carbon fiber because they would crumple at the walls. To make them strong enough, the walls would need to be so thick that the rims would be extremely heavy. For this reason, deep aluminum rims over 50mm deep are rare. If you want deep aero rims, carbon fiber is usually your only option.

Regardless of the rim material you choose, you will want to factor in both rim weight and aerodynamics when choosing rims. There there is a compromise to make.

If you regularly climb steep grades at low speeds, you’re better off prioritizing wheel weight rather than aerodynamics. In this case, you’ll want to choose lightweight wheels with shallow rims. If you ride flat ground and gradual grades at higher speeds, you’re better off prioritizing aerodynamics. In this case, you’ll want to choose deep and aerodynamic rims. Weight may be a bit less important. 

For most riders, the cutoff is a grade of around 4.5%. If you ride grades that are steeper than 4.5%, you’re usually better off choosing lighter wheels. If you ride grades that are less than 4.5%, you’re usually better off choosing aerodynamic wheels. The reason is that you can reach speeds over 9mph on more gradual grades so aerodynamics benefits outweigh the extra weight. You can get away with deeper rims if you go with carbon fiber because the material is so much lighter than aluminum. 

Another consideration is wind. Deep rims make your bike easier to blow around because they catch more wind from the sides. They act as a sail. This can make the bike feel squirrely. A heavy gust of wind or a large truck passing you could blow you off your line or even off the road. If you regularly ride in windy conditions or near heavy traffic, you might feel more confident with shallow rims. 

When choosing aerodynamic rims, you’ll also want to keep rim width in mind. Remember the rule of 105, as outlined in the previous section. Most modern aero wheels are designed to maximize efficiency when paired with 23-25mm road tires. 

Winner: If you’re buying aerodynamic wheels, carbon fiber is the better material because they are lighter. You can buy deeper carbon rims without the rims being too heavy. Aluminum rims typically aren’t made quite as deep because they would weigh too much. 

Clincher Vs. Tubeless Vs. Tubular Carbon Fiber and Aluminum Rims

When buying bike wheels, you’ll have to choose between three different types: clincher, tubeless, and tubular. Each wheel type uses a different type of tire. It is important to note that tubular wheels are not compatible with clincher or tubeless tires. Clincher and tubeless tires can be used on both clincher and tubeless rims, in most cases. In this section, I’ll briefly outline the difference between the three wheel types and list a few pros and cons of each.

Clincher Wheels

Clincher wheels use clincher tires. These tires are open at the bottom, like car tires. Clincher wheels have a rubber airtight inner tube inside to support the tire. When you inflate the tubes, they expand and put pressure on the inside of the tire. This tightens or ‘clinches’ a hard bead around the edges of the tire against the rim. The tube holds the air and the tire sits against the tube. 

Clincher wheels can be drilled to run either Schrader or Presta valves. You can buy clincher wheelsets made from either carbon fiber or aluminum. 

These are the most common type of bike wheels. They are found on almost all entry-level to mid-range bikes. They are also found on pretty much all older bikes. You probably rode clincher wheels as a kid. These days, clincher wheels are less common on high-end mountain bikes, gravel bikes, and road bikes. Many cyclists upgrade from clincher to tubeless tires and wheels.

Clincher wheels are ideal for those who are not very mechanically inclined, those on a tight budget, and beginner and recreational cyclists. They are easy to install and maintain. If a tube gets punctured, it’s easy to apply a patch or replace the tube. All you need to carry to repair a flat is a patch kit, tire levers, and a pump. Spare tubes and patches are common and affordable.

Performance-wise, clincher wheels don’t offer quite as much traction or comfort as tubeless wheels. The sacrifice in performance is pretty minimal. One major drawback is that flats are more common. Particularly while riding off-road. Tubes are easy to puncture. Running over a nail, piece of glass, or thorn can cause a flat. 

In most cases, it is possible to run clincher wheels tubeless. This is called a DIY or ‘ghetto tubeless’ setup. This involves sealing the rim and putting sealant inside of the tire. For more info, check out this guide.

Tubeless Wheels

A mountain bike with carbon tubeless rims

Tubeless wheels are designed in a way that allows the tire to form an airtight seal with the rim without the need for a tube. The tires have an open bottom, just like clincher tires. When inflated, air puts pressure on the inside of the tires so the bead sits tightly against the rim. 

For this to work, the rim must be sealed up airtight with tubeless rim tape so air can’t escape through the spoke holes. During installation, a liquid sealant is poured inside the tire. This helps to seal up any gaps or holes so the wheel and tire remain airtight. Clincher wheels can be drilled to run either Schrader or Presta valves. Tubeless wheels can be made from either carbon fiber or aluminum. 

Tubeless wheels and tires offer several advantages over clincher wheels. Most importantly, flats are much less common. This is possible because the sealant in the tire repairs small punctures before the air can leak out. If you hit a thorn or nail and your tire gets punctured, you won’t even have to stop. This is great for off-road riding where you’re likely to encounter sharp debris. It’s also ideal for long distance cycling, such as bicycle touring and bikepacking. You may be able to ride tens of thousands of miles without having to repair a puncture. 

If you get a large puncture or tear that the sealant can’t fill, you can sew up the hole or apply a patch. If this doesn’t work, you can install a tube.

Another advantage of riding tubeless is that you can run your tires at lower pressure because there is no tube that can get pinched and cause a flat. This increases traction by allowing the softer tire to deform so more tread can contact the ground. It also improves comfort. The softer tire can absorb more bumps.

You’ll want to be careful with this if you run carbon fiber wheels. If you run your tire pressure too low and you hit an obstacle and your tire bottoms out, you risk cracking your rim. The risk is lower with aluminum rims because they are more durable. 

One problem you can encounter with tubeless aluminum rims is dents, nicks, and scratches on the bead where the tire meets the rim. These can make it impossible to get an airtight seal. If you can’t get your tire to seal, you’ll have to run tubes or replace your rim.

Another drawback is that tubeless tires can be a bit of a hassle to install and maintain. There is a learning curve. Getting your tires to seal airtight can be a challenge. There is a learning curve. You need to inflate the tire quickly so it seals agains the rim. Repairing large punctures or sidewall tears can be difficult as well. You may have to sew a sidewall, make a patch, or plug a puncture. You need more tire repair tools in your repair kit when you ride tubeless. This adds weight. 

These days, tubeless wheels are standard on most mid-range to high-end mountain bikes and gravel bikes. Some road riders and cyclocross riders are switching from tubular to tubeless tires these days as well. Many riders convert their clincher wheels to tubeless to take advantage of the many benefits of riding tubeless.

For more info, check out my complete guide to tubeless vs tubed bike tires.

Tubular Wheels

Tubular tires are like an inner tube with tread. The tires are completely sealed. They are not open on the inside like clincher tires. Tubular tires do not need a separate tube because the tube is sewn or molded into the inside of the tire. In other words, the tire and tube are one unit. Tubular tires are usually glued to the tubular rim. This prevents the tires from moving around on the rim. 

Tubular wheels do not have a rim wall and tubular tires do not have a bead. For this reason, tubular wheels work only with tubular tires. They are not cross-compatible with clincher or tubeless tires. 

Tubular wheels are commonly used in competitive road and cyclocross racing as well as triathlons. Racers often prefer tubular wheels and tires because the system is lighter and has less rolling resistance than clincher wheels. Tubular wheels also allow you to run lower tire pressure than clincher wheels. This is possible because tubular wheels and tires are more resistant to pinch flats. Running lower tire pressure allows for better traction and a more comfortable and supple ride. Tubular tires are often a bit more durable than clincher tires as well. Flats are less common

The main drawback of tubular tires is that flats are difficult to repair. Because the tires need to be glued to the rim, the job is a bit more complicated. There is also a learning curve to installing tubular tires. You must learn how to glue the tire to the rim properly. This can be a messy and annoying job. 

Many racers have two sets of wheels. They have one set of tubular wheels that they ride only during races. These wheels would likely be made out of carbon fiber. Racers often own a second set of clincher or tubeless rims that they use for day-to-day riding and training. These could be made from either carbon fiber or aluminum. 

Hubs

When building or buying a set of wheels, you’ll also want to take a bit of time to consider the hubs you’re going to use. The hubs play a major role in the durability, longevity, performance, and efficiency of your wheels. 

For example, high-end hubs are often lighter. They also use higher quality bearings that create less friction. This creates less rolling resistance and improves efficiency. High-end hubs often require less frequent maintenance and last longer than lower end-end hubs as well. 

In reality, the average cyclist won’t notice much of a difference in weight and rolling resistance between mid-range and high-end hubs. Hubs also last tens of thousands of miles if they’re maintained properly. Maintenance intervals are long. You may only need to maintain your hubs once every year or two. 

Hub Engagement

One difference between low and high end hubs that is a bit more noticeable is hub engagement. Your cassette is mounted to a ratchet mechanism in the hub. This mechanism allows your rear wheel to spin freely while you’re not pedaling or while you’re pedaling backwards. When you begin pedaling, the mechanism engages. Hubs have a set number of points of engagement (POE). These engagement points are the clicks you hear when your hub is freewheeling.

The ratchet mechanism of a hub contains a series of pawls. These are spring-loaded bars are mounted to a ring on the inside of the hub. The paw pivot against a ring of teeth or ridges on the outside of the freehub body.

As the wheel spins forward, the ridges pass freely over the spring-loaded pawls. This is what makes the clicking sound you hear while coasting or freewheeling. When you begin pealing, the pawls spring up and catch on the teeth inside of the hub. This allows you to transfer your pedaling power to the hub to power the wheel. 

This ratchet mechanism is what allows the wheel to only move freely in one direction relative to the cranks. For example, the wheel can freely roll forward without the cranks moving. When you roll the bike backward, the cranks move backward because the pawls catch.  

The point where the pawls bite the ridges in the hub is called the point of engagement. There are a limited number of points of engagement because there are a limited number of pawls and there is space between the pawls. 

Some hubs have more points of engagement than others because some hubs have more pawls and teeth than others. Low-end hubs often have 18-24 points of engagement. High-end hubs usually have 36+ points of engagement. These points are equally spaced around the hub. 

Hub engagement can also be expressed in degrees of engagement. This number represents the maximum number of degrees you must rotate the cranks before the hub engages and begins moving the wheel. This is the angle of engagement. For example, if there are 18 points of engagement, the angle of engagement would be 20°. This is calculated by dividing 360 degrees by 18 (360/18=20). If the hub has 36 points of engagement, the angle of engagement would be just 10°. The more points of engagement a hub has, the less distance you have to turn the cranks to engage the hub and start moving the wheel.

Most high-end hubs these days have 72 points of engagement with an angle of engagement of 5°. Industry Nine released the hydra Hydra wheelset that comes with an impressive 690 points of engagement with an angle of engagement of just 0.52° (360/690=0.52). You can read more about these hubs here.

Quicker engagement is more important for off-road riders than road riders. Particularly if you ride technical trails or steep trails. You may not be able to pedal continuously on rough terrain because your pedal would strike an obstacle sticking out of the ground. You oftentimes can’t make complete pedal strokes.

When riding technical terrain, sometimes you have to make quick, short pedal strokes to power over obstacles and avoid pedal strike. Sometimes the terrain is too rough to peal through. On steep terrain, sometimes you have to make a partial stroke, backpedal, then make another partial stroke. This is called ratchet pedaling. You may also have to balance so you don’t fall over while riding at low speeds. Having more points of engagement these pedaling techniques easier because you don’t have to move the cranks as far before they catch.

When there are fewer points of engagement, there are dead zones when you start turning the cranks. This makes it more difficult to make short pedal strokes. It also becomes more difficult to balance. You may have to get off the bike and walk through technical sections. 

Fast engagement is particularly helpful for racers because you can start delivering power a fraction of a second faster when you start pedaling. For example, when coming out of a corner, you don’t have to turn the cranks as far to start producing power. You can also more produce power while riding through particularly rough sections of terrain by sneaking in extra partial pedal strokes here and there. You can ratchet your pedals back and pedal a bit to gain some extra power. This comes in handy while riding over bumpy sections of trail. 

For road riding, the number of engagement points or angle of engagement is less important because you’re pretty much always pedaling. You might only notice while starting from a stop or exiting a hard corner. 

The point is that your hubs can play an important role in the performance of your bike. You wouldn’t want to pair high-end carbon fiber rims with cheap hubs. You’ll defeat the purpose of buying expensive rims. If you’re going to buy high-end rims, you’ll want to pair them with an equal quality hub to maximize performance. Quality hubs allow you to pedal through rougher sections of trail without having to walk your bike.

Spokes

A rear bike wheel

The spokes connect the hub to the rim. They play an important role in the weight, stiffness, aerodynamics, and strength of the wheel. The best spokes depend on your weight, the type of bike, and how you ride the bike. A few decisions you’ll have to make when choosing wheels include:

  • Number of spokes- This is a compromise. Wheels with more spokes are stronger and stiffer. Wheels with fewer spokes are lighter. Mountain bikes usually have 28-32 spokes. Road bike wheels typically have 16-28 spokes. Touring bikes often have 36-48 spoke wheels for extra strength. On many bikes, the front wheel will have 2-4 fewer spokes than the rear wheel because the front wheel holds less weight and doesn’t have to handle the pedaling force. 
  • Spoke material- Most bike wheel spokes are made from steel. Several different alloys are used. The alloy can affect the weight, strength, and corrosion resistance of the spoke. Carbon fiber spokes are also available. These are lighter and stiffer than steel. Wheels with carbon spokes tend to use fewer spokes. 
  • Spoke shape- Spokes are available in a few different shapes. The most common straight gauge spokes. These have the same diameter throughout their length. Most measure 14, 15, or 16 gauge wire thickness. They are the strongest and heaviest type of spoke. Single butted spokes are thick at the ends then become taper down in the center. They are lighter than straight gauge spokes. Double-butted spokes are also available, which become even thinner in the center than single butted spokes. These are lightweight and offer some flexibility. They can twist when tensioned. Aerodynamic bladed spokes are also available. These have a wing or oval shape to reduce wind resistance. These are lightweight but can be tricky to install and adjust. For more info on spoke shape, check out this guide.
  • Lacing pattern- The lacing pattern plays a big role in the strength and stiffness of the wheel. This helps the wheel handle pedaling and braking forces. The more times the spokes cross one another, the stronger and stiffer the wheel will be. The most common spoke lacing patterns include two cross and three cross. Wheels with 24 spokes can cross twice. Wheels with 32 spokes can cross three times. For more spoke patterns, check out this guide.
  • J bend or straight pull- J bend spokes are bent 90° at the end. Straight pull spokes are straight. They require dedicated hubs. 

Who Should Choose Carbon Fiber Wheels?

Carbon fiber wheels are ideal for those who want to get the best performance out of their bike. The light weight allows the bike to accelerate quickly and ride efficiently. The stiffness of carbon fiber improves handling. If you’re not the strongest rider, you can buy yourself a bit of an advantage by switching to carbon wheels. 

Modern design and manufacturing techniques give carbon fiber wheels excellent comfort and ride quality as well. They can be optimized for both performance and comfort.

In addition, carbon wheels require a bit less frequent maintenance because they stay true longer. Those who don’t enjoy working on their bike may appreciate this. 

Riders who have never experienced wheel failure may also appreciate the benefits of carbon fiber. If you’re easy on your wheels, you don’t have to worry about flat spots or dents. Modern carbon wheels are extremely durable and long-lasting if they’re treated properly. 

Those who aren’t on a budget will probably prefer carbon wheels. They offer a more premium experience. If you can afford to spend an extra thousand or so dollars on your bike, you might as well go with carbon.

Who Should Choose Aluminum Wheels?

Those who don’t care about performance will be better off with aluminum wheels. If you just ride recreationally around town or commute to work, there is really no reason to upgrade to carbon.

Aluminum wheels are ideal for those who are on a budget. The price of aluminum wheels is significantly lower than carbon fiber. If they wear out or get destroyed, aluminum rims are much cheaper to replace. Over time, this saves you thousands of dollars. A single set of aluminum rims can cost $1000 less than comparable carbon rims. 

Those who are hard on their rims and have experienced multiple rim failures in the past are also better off going with with aluminum wheels. Aluminum rims tend to last longer because they are more durable. They may bend or dent but remain rideable. They are also cheaper to replace. If you go through multiple rims per season, you’re better off sticking with aluminum unless your budget is unlimited. 

Those who ride in remote areas away from civilization and in developing countries are also better off with aluminum rims due to their durability, reliability, and repairability. Aluminum can survive a harder impact. If a rim fails, it can be bent back and ridden back to civilization in most cases. Aluminum rims are less likely to leave you stranded. For this reason, bicycle tourists and bikepackers are better off with aluminum rims. 

Those who are concerned with safety may also prefer aluminum rims. They are less likely to overheat and fail. During a hard impact, they usually won’t fail catastrophically. Aluminum gives you some warning signs before it breaks.

Some riders also find that aluminum rims offer a more comfortable ride. Carbon rims can feel too harsh. 

My Choice: Aluminum Vs Carbon Fiber Wheels

If money were no object, I would choose carbon fiber wheels without a second thought. They perform better in pretty much every way because they are lighter and stiffer. The ride quality and handling of modern carbon rims are excellent. Modern carbon rims are also very reliable. 

I’m not the strongest rider. If I can increase my speed or efficiency or gain a bit of an advantage by upgrading a component, I usually will. Carbon fiber wheels give me a slight edge over aluminum. I also enjoy using the most modern equipment. 

The cost is the main factor that prevents me from running carbon rims on all of my bikes. I simply can’t afford to spend thousands of dollars on wheels. I also find that I am much more careful while riding carbon rims out of fear of damaging them. This makes me ride a bit more slowly and carefully than I otherwise would. Even though modern carbon fiber rims are very durable, I still tend to treat them gently. 

For the types of riding I do, aluminum rims perform just fine. I do not ride competitively so performance isn’t all that important. I spend much of my riding time touring or riding recreationally around town. The extra durability of aluminum wheels brings me peace of mind. If the extra weight and flex mean it takes me a few seconds longer to get where I’m going, so be it. 

Final Thoughts about Carbon Fiber Vs Aluminum Bike Wheels

As you can see, there are compromises to make when deciding between carbon fiber and aluminum wheels. For casual and recreational riders who don’t care about time or speed, aluminum is probably the best choice. The reliability and durability allow you to ride your bike without worrying about causing damage or getting stranded. They’re easy on the wallet as well. 

Riders who need to get the best performance possible out of their bike, such as competitive riders, will be better off with carbon fiber wheels. When it comes to performance, the wheels are possibly the most important component of the bike. Being lighter weight and stiffer, carbon wheels allow you to ride a bit faster and more efficiently. 

If you’ve never ridden a bike with carbon wheels before, it’s worth taking one for a test ride. Most riders notice the weight difference right away. The stiffness is a bit less noticeable. You have to really get to know the bike and push it to feel the difference. 

You may find that you prefer one wheel material over the other. Some riders prefer the comfort of more flexible aluminum rims. Others prefer the raw performance of stiff and lightweight carbon fiber rims. 

Do you prefer carbon fiber or aluminum wheels? Share your experience in the comments below!

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