When choosing a new bicycle, the frame is arguably the most important individual part. The frame greatly affects the bike’s weight, ride quality, and handling. In this guide, I outline the pros and cons of a steel vs aluminum bike frame. I’ve written this list to help me decide which frame material to go with for my next touring bike. Hopefully, it helps you as it has helped me.
Steel Bike Frame Pros
- Easy to repair- After years of use your bike frame will eventually fail, regardless of the material. With a steel frame, pretty much any welder can repair it. This feature is particularly important for bicycle tourists traveling through developing regions. It doesn’t matter where in the world you are, you can always find someone who knows how to weld steel. Even in small villages in the developing world. The weld may not look pretty and the frame may not be as strong as it originally was, but it will get you back on the road. Finding someone to weld aluminum or titanium can be a challenge, even in the developed world.
- More comfortable- Steel frames aren’t completely rigid. They have a bit of give. This dampens vibrations and reduces shocks. It allows for a smoother ride. When you hit a bump in the road, it won’t feel quite as jarring on a steel framed bike. Aluminum is more rigid. You feel bumps and vibrations more as you ride.
- Steel frames last longer- Because steel is more pliable, it doesn’t fatigue as quickly as aluminum. That means your frame can last longer and take a bit more beating without failing. Of course, after enough years of abuse, any frame will fail. You should expect decades of use out of any bike frame if you treat it right. My Schwinn High Sierra that I converted into a touring bike has a steel frame that was made before I was born.
- Steel frames are better for bicycle touring, commuting, and mountain biking- These types of riders generally value frame strength more than weight. Steel offers greater durability than aluminum.
- You can change the hub spacing on a steel frame- If you need to install a slightly wider or more narrow rear hub, you can bend the rear dropouts a bit to make it fit. You can pretty easily move them 5-10 mm in either direction. This allows you to use a wider range of hubs when the time comes to upgrade or replace your wheels.
- Steel frames may be safer- Steel and aluminum frames fail in different ways. A steel frame gives you a bit more warning. It won’t just fail and break in half. Steel bends or cracks slowly. If you inspect your steel frame often, you’ll have plenty of warning before it fails. Aluminum, on the other hand, can fail catastrophically. Aluminum doesn’t bend, it breaks. You could be speeding down a hill when your aluminum frame suddenly decides to break in half and throw you to the ground. Of course, this is incredibly rare, but it can happen.
- You can install S&S couplers- If you plan to fly with your bike, you may want to consider having S&S couplers installed at some point. These allow you to break your frame down into 2 pieces so you can pack your bike into an airline acceptable size checked bag. The goal here is to avoid expensive oversized bag fees that many airlines charge for bicycles. S&S couplers are only possible to install on steel and some titanium bike frames. They are not compatible with aluminum frames.
- Steel is real- It’s the classic bike frame material. People have been riding steel bikes for over a century. Personally, I think steel frames look the best too. I find the small round tubes more visually appealing than thick aluminum tubes.
Steel Bike Frame Cons
- Steel is heavy- It’s the heaviest bike frame material used today. The main reason to choose aluminum, titanium, or carbon fiber over steel is because it saves a considerable amount of weight. If you like to measure every gram that you put on your bike, you may want to stay away from steel frames.
- Steel is less efficient- Steel flexes. It’s not completely rigid. Each time your frame flexes, you waste energy that otherwise could drive you forward. The energy goes into the bike frame where it’s not needed. For recreational riders, the loss is minimal enough that it doesn’t really matter. For competitive riders, it may be something to think about. You’ll use more energy covering the same amount of distance when riding a steel frame.
- Steel is slower- Because of the added weight and lower efficiency, you probably won’t be quite as fast when riding a steel frame. Again, this really only matters for competitive riders.
- More expensive- Steel bike frames cost more than aluminum. The reason is that steel frames are slightly more time consuming to produce. Aluminum frames were initially introduced because they are cheaper to mass manufacture. This led to cheaper bicycles. You can see this when you go to a big box store. For example, if you look at the bikes at Walmart, they are mostly aluminum.
- Steel rusts- This isn’t a problem you have to worry about with other frame materials. If a frame gets rusty enough, it can weaken to a point that it’s not safe to ride. The most likely part of your bike to rust is the inside of the frame. To prevent this, you should apply a rust inhibitor. Also, store the bike in a place where it stays dry. If you scratch some paint off of your frame, you’ll want to seal it up with some nail polish or something so it doesn’t begin to rust. If your steel frame is already rusty, check out these rust removal tips from slocyclist.com to remove it before it gets too bad.
- Steel is less technically advanced- If you are the kind of person who has to have the best, most advanced gear, consider a carbon or titanium frame.
Aluminum Bike Frame Pros
- Aluminum frames are lighter- Aluminum has about a third of the density of steel. That means that aluminum is lighter by volume. This doesn’t mean that an aluminum frame weighs a third of a steel frame. Because aluminum isn’t quite as strong as steel, more material must be used to make the frame strong and durable enough. Even with the extra material, aluminum bike frames are usually lighter than steel.
- Cheaper- Manufacturers initially introduced Aluminum frames because they were cheaper to mass-produce than steel. If you’re on a budget, aluminum frames offer the best value. Most budget bikes use aluminum frames.
- More efficient- Because aluminum is so rigid, less energy is lost due to flexing of the frame. Instead, you use this energy to drive you forward. While the increase isn’t too significant, it could mean a few seconds difference in a race.
- Aluminum frames are faster- Because of the lighter weight and increased efficiency, most riders can maintain a slightly higher average speed with an aluminum frame.
- Aluminum frames are better for racing- Racers value weight and efficiency over strength and durability.
- Can be more aerodynamic- Aluminum bike frames don’t have to be made out of round tubes like steel. This allows frame builders to mold the fork and frame into more aerodynamic shapes. This further increases efficiency and speed.
- No rust- Aluminum does not rust. It does, however, corrode. Strangely, this is beneficial in a way. Aluminum forms aluminum oxide when it corrodes. This creates a thin film that protects the rest of the metal from further corrosion. Aluminum oxide is also much stronger than rust. This means that your aluminum frame isn’t weakened when it begins to corrode and it won’t corrode away over time. For more info, check out this interesting article on aluminum corrosion from Bicycle Universe.
- Aluminum frames can look more modern- Because the frame tubes can be molded into more aerodynamic shapes, the frames can look a bit more jazzy. Some cyclists prefer the more modern look.
Aluminum Bike Frame Cons
- More difficult to repair- Aluminum requires specialized equipment and know-how to weld. If your aluminum frame cracks, your average backyard welder can’t repair it. You’ll have to find someone who has the tools and knowledge to do it. This can be a challenge if you’re riding through a rural area or a developing country. You might have to hitchhike to the nearest capital city to find someone to make the repair. In some cases, you cannot repair aluminum frames.
- Less comfortable- Because aluminum is so rigid, it doesn’t absorb any shocks or dampen road vibrations. A rigid frame transmits every bump in the road right into your body. The ride can feel harsh. Of course, if you have suspension, this isn’t a problem. The geometry of your frame also greatly affects the ride quality.
- Aluminum frames don’t last as long- Aluminum fatigues more rapidly than steel. Eventually, the frame will fail. It just can’t take as much of a beating as a steel frame can. Of course, with proper treatment, you can expect decades of use out of any frame.
- You can’t change hub spacing- Because aluminum is so rigid, you can’t bend the rear dropouts without risking damage. You could weaken or crack the metal. This means you can’t adjust your hub spacing like you can with a steel frame. This limits your hub options when replacing or upgrading wheels.
- Aluminum frames may be more dangerous- Aluminum can fail without warning. A sudden catastrophic failure of your frame could mean injury. Imagine bombing down a hill at 30 miles per hour when your frame suddenly splits. While this isn’t likely, it is possible. Steel gives you some warning signs when it’s about to fail. It slowly develops cracks or bends. This gives you time to make repairs or get a new frame before a complete failure. Of course, aluminum doesn’t always fail violently.
- You can’t install S&S couplers- These allow you to take your frame apart to pack it for packing. Aluminum frames aren’t compatible due to the nature of the metal. You can only install S&S couplers on steel and some titanium frames. For more info, visit sandsmachine.com.
More Cycling Pros and Cons Analyses from Where the Road Forks
- Drop Bars Vs. Flat Bars
- Bikepacking Bags Vs. Panniers
- Flat Pedals Vs. Clipless
- 700c Vs. 26 Inch Wheels
- Disc Brakes Vs. Rim Brakes
- Chain Vs. Belt Drive
- Tube Vs. Tubeless Bicycle Tires
- Internal Gear Hub Vs. Derailleur
- Presta Vs. Schrader Valves
Types of Metals Used
Most bike frame manufacturers use an alloy of either steel or aluminum to craft the frame. An alloy is a metal that is mixed with other elements to improve the metal’s characteristics. The goal of using an alloy is to increase the strength or decrease the weight of the frame. Several different alloys of both steel and aluminum exist with slightly different characteristics.
Types of Steel Bike Frames
Steel is an alloy of iron and carbon. To make it suitable for bicycle frame building steel is usually mixed with traces of other elements to make it both stronger and lighter. Types of steel used for bicycle frames include:
- High-Tensile- This is the weakest and heaviest type of steel used for manufacturing bike frames. It is common on low-end bikes and older bikes. High-tensile steel is also known as carbon steel or high-ten.
- Chromoly- This type of steel is an alloy made by mixing steel with chromium and molybdenum. Adding these elements improves the strength to weight ratio of the steel. Chromoly is used for mid to high-end steel bike frames. Several types of Chromoly exist. The most common is 4130.
- Other types of steel- Manufacturers continually experiment with various steel alloys and different heat treatments to find the lightest and strongest material. Some steels are designed to be lighter. Some are designed to be stiffer.
For more info, check out this extensive guide on types of steel used for bike frames from Gravelcycling.
Types of Aluminum Bike Frames
Pure aluminum isn’t strong enough to use for bicycle frame building. Usually, aluminum is mixed with silicon, magnesium, or zinc to make it stronger and more durable. 6061 and 7005 are the most common types of aluminum used for bike frames. Of the two, 6061 is slightly better due to its lower weight.
Bike Frame Tubing Types
The shape of the tubes greatly affects the weight and rigidity of the frame. Tube types include:
Plain gauge tubing
These are straight tubes that are the same thickness throughout. They don’t use any butting, oversizing, or strange shapes. These are the cheapest due to their simplicity. They are strong and easy to manufacture. Plain gauge tubing offers the best value. Your only sacrifice is a bit more weight.
Butting is a method of construction used for reducing frame weight. Manufacturers achieve this by removing unnecessary material from the frame tubes. For example, a tube can be made thinner in the middle without sacrificing anything in terms of strength or durability. The tubes need to be thicker near the ends where they experience more stress. Butting can reduce the weight of a frame by 3-4 pounds. Type of butting include:
- Double butting- Manufacturers place extra material on each end of the tubes. The middle of the tubes are thinner. This is common mid to high-end bikes.
- Triple butting- Similar to double butting except with three layers. The ends are the thickest part. Further in the tube, the walls thin. Even further in the tube, the walls thin again. This cuts even more weight. You’ll find this on high-end bikes.
Both aluminum and steel frames can be butted. Internal butting is the most common these days. This means that the outside of the tubes are all uniform. That is, you can’t identify butted frames by looking at them. The manufacturer will indicate whether or not the frame is butted in the specs.
Bike Frame Tubing Connection
The individual tubes that make up your bicycle frame are joined together using either welding or brazing. The type of connection used doesn’t really affect the way the bike rides. Which type of connection used depends on looks and price. Some frames use a combination of welding and brazing. Generally, manufacturers braze smaller joints and weld larger joints.
Welded Bike Frames
Welding melts the frame tubes with a filler metal to create a single, solid piece of metal. Steel, aluminum, and titanium bikes can be welded.
Manufacturers use two types of welding to build bike frames, TIG and MIG. Generally, TIG welding creates a stronger, cleaner looking weld.
Brazed Bike Frames
Brazing is a process which involves melting a filler metal. This molten metal is then used to connect the bicycle frame tubes. In this case, the frame tubes do not melt. They stick together with the filler metal acting like glue. Brass and silver are common filler metal materials.
A variation of a brazed bicycle frame is lugged brazing. In this case, the frame tubes are fitted inside of a metal sleeve called a lug. The frame builder then brazes the lug to the frame.
For more info, check out this guide to welded vs brazed bike frames from missionbicycle.com.
Other Bike Frame Materials
Aluminum is the most common bicycle frame material in use today, followed by steel. Other common frame materials include:
Titanium Bike Frame
Titanium offers the strength of steel at a much lighter weight. In fact, it weighs about 40% less than steel. It’s the strongest and lightest metal used for bicycle frame building.
Another benefit of titanium is the fact that it has some flex while riding. This gives the bike some natural shock absorption. Titanium flexes less than steel but more than aluminum or carbon. Many cyclists love the ride quality that titanium bikes offer.
Titanium is also corrosion-resistant. This means that you don’t have to worry about it weakening over time.
Titanium is commonly found on high end touring, road, and cross-country mountain bikes. This is a ‘buy it for life’ frame material. A high-quality titanium frame should give you decades of good use if taken care of. In my opinion, titanium really offers the best qualities of aluminum and steel frames with very few drawbacks.
Titanium bike frames have two main drawbacks. First is the cost. Titanium frames are expensive. The raw material is expensive, and it’s just a tricky metal to work with. Welding and shaping titanium takes more skill than steel. Both of these points add to the cost.
The second problem with titanium is repairability. If your frame fails while touring in a rural or developing area, finding someone to repair it can be a challenge. Not every village has someone with the tools or know-how to weld titanium. Also, you probably don’t want just anybody welding on your $2000-$4000 custom titanium frame. You want somebody who knows what they’re doing. Titanium frames rarely fail.
Carbon Fiber Bike Frame
Carbon fiber is the lightest material currently used to build bike frames. This material was initially developed for use in the aerospace industry where parts need to be as light and strong as possible.
Carbon fiber is manufactured by weaving fibers together in sheets. These sheets are then bound together with a glue-like resin. Several sheets are combined to form a piece called a laminate which is used to make a bike frame. The resulting material is incredibly strong and lightweight.
Several grades of carbon fiber are available. These vary in weight and strength. Carbon fiber bike frames vary greatly in price. Generally, the higher the grade of carbon fiber used and more complex the frame, the more expensive it will be.
Really, the only benefit a carbon fiber bike frame offers over any other material is the weight. The lightest frames you can buy are made of carbon fiber. If you are racing or training and need the lightest possible bike, carbon fiber is probably your ideal frame material.
Drawbacks of Carbon Fiber Include:
- High failure rate- Carbon fiber frames are more likely to fail than steel, aluminum, or titanium.
- Expensive- Prices vary widely. Carbon fiber frames are more expensive than steel or aluminum. You can pay anywhere from $1500-$6000 for a carbon fiber bike frame.
- Less comfortable ride- Because the material is so rigid, the ride may feel harsher. Carbon fiber doesn’t dampen bumps or vibrations like steel or titanium can.
- Not as repairable as other materials- If your carbon fiber frame cracks or gets dented, you can repair it with a carbon fiber repair kit. The problem is that the repair may not last too long. In some cases, you’ll just need to buy a new frame. An experienced welder can repair a steel or titanium bike to be as strong as it was when it was new.
For more info, check out my carbon fiber vs aluminum frame guide.
Bamboo Bike Frame
These are kind of a novelty at this point. Having said that, bamboo is a legitimate bike frame material. Most bamboo bikes are made by starting with strong bamboo poles then binding the joints together with fiber and resin. These joints are similar to carbon fiber. The result is a strong, lightweight bike frame.
The biggest benefit that bamboo bikes offer over other frame material options is the fact that they are made of a renewable material. Bamboo grows quickly and easily in many parts of the world. These are the most environmentally friendly bike frames available.
The main drawback of a bamboo frame is the fact that it’s difficult to repair. You can’t just take it to a welder. You need to find someone who knows how to work with the material. This most likely means the manufacturer. Bamboo bikes are also a bit less durable than more common frame materials like steel, aluminum, or titanium.
For more info, check out this article about bamboo bikes from Bikes Reviewed.
More Factors to Think about When Choosing a Bicycle Frame
When choosing a frame, you need to consider the types of parts that you want to install on it. For example, you must decide:
- Wheel size- Most frames work with only one size of wheel. Usually 26 inch, 700c, or 650b. The reason that you can’t use different wheel sizes is that your bottom bracket may be too low or too high. You can also have problems with brake compatibility and tire clearance. There are exceptions to this. Some frames work with multiple wheel sizes.
- Tire width- Make sure your frame offers enough clearance for the tires that you plan to use. For example, if you plan to ride off-road, you’ll want a frame that allows you to install tires that are at least 2.5 inches wide.
- Internal gear hub or derailleur- Most all frames are compatible with derailleurs. If you plan to install an internal gear hub at some point, you’ll want to choose a frame that has a mounting point for the chain tensioner.
- Rim brakes or disc brakes- Not all frames have mounts for both.
- Thru axles or quick release axles- You can’t really convert from one to the other. To help you decide, check out my thru axle vs quick release pros and cons list.
My Bike Frame Material of Choice: Steel Vs Aluminum
For me, steel is the winner. It offers an excellent combination of affordability, durability, and ride quality. The ability to repair my frame anywhere also brings peace of mind to me, as a bicycle tourist.
Having said this, I would love to ride a custom-fitted titanium frame. The material really offers the best of all worlds. Unfortunately, a titanium frame is just out of my price range at this time.
Bamboo frames also intrigue me. Something about the mixture of natural materials with modern bicycle components just looks cool. A bamboo frame is really a work of art. Each one is different. I wouldn’t choose this material for my touring bike or commuter though due to durability concerns.
Other Considerations When Choosing a Bike Frame
When buying a bike frame, It’s important that you choose the right size. If your frame is even slightly too large or small for you, you may experience joint pain or discomfort. If you fall between two sizes, it’s generally better to choose the smaller frame. You can make a smaller frame fit you by installing a longer stem and seat post. Most bike shops will measure you for free to help you choose the right size frame to fit your body.
Bikes are measured in centimeters from the center of the bottom bracket to the top of the seat tube. They usually come in steps of 2 cm. Mountain bikes often come in sizes small, medium, large, etc. Sizes vary by brand as well. If you have a 56 cm Trek, you may ride a slightly different size when you switch to Specialized, for example. To compare sizes, you can look at the exact measurements on the manufacturer’s website.
The geometry of the frame greatly affects the ride characteristics of a bike. Characteristics include handling, comfort, and steering responsiveness. The most important measurements are head tube, seat tube, top tube, and chainstay length as well as the wheelbase.
For more info, check out this great article about frame geometry from Bike Exchange. It explains each measurement and how it affects the bike’s performance.
Frames have a maximum recommended rider weight listed in the specifications. If you’re over around 180-200 pounds, you’ll probably want to go with a frame with a strength rating on the stronger side. Steel and titanium frames can generally support more weight because they are able to flex more without failing.
Tip: If you’re a particularly heavy rider, you may want to consider a touring bike. Manufacturers design these to carry a rider plus lots of gear. They can handle more weight than most frames.
Aluminum is the cheapest bike frame material. Most budget bikes are aluminum. Steel is affordable as well depending on the grade. Carbon fiber has come down a lot in price but is still on the higher end. Titanium is the most expensive.
How Long do You Plan to Ride the Bike?
Not all frame materials offer the same longevity. If you plan to keep the bike for many years or you plan to put a lot of miles on it, go with a steel or titanium frame. These materials don’t fatigue as quickly as the others. A good frame could last a lifetime if you take care of it.
If you don’t really care if the bike lasts for the rest of your life and you value weight over anything else, aluminum or carbon fiber frames may be for you.
Final Thoughts: Steel Vs. Aluminum Bike Frame
For most riders, a steel frame makes the most sense. For a small weight sacrifice, you gain increased durability, repairability, and comfort. Most of the drawbacks of steel have to do with performance. Most cyclists, including myself, don’t really care about performance. We ride for fun or transportation. Not for the fastest time.
Of course, circumstances exist where an aluminum frame is the better option. If you’re on a tight budget, you can save some money by choosing a bike with an aluminum frame. Racers or those who care about keeping time of their rides can also benefit from the stiffer, more efficient ride that high-end aluminum frames offer.
Where do you stand on the steel vs aluminum bike frame debate? Share your experience in the comments below!
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