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1X Vs 2X Drivetrain: Pros and Cons

In 2012, Sram introduced the first off the shelf 1x drivetrain. In the years since, 1x drivetrains have increased in popularity to a point that the majority of all new mountain bikes, bikepacking bikes, and gravel bikes feature them. Some road cyclists are even switching to 1x. That said, most manufactures still offer 2x and 3x options. This guide analyzes the pros and cons of using a 1x vs 2x vs 3x drivetrain. We’ll look at gear range, gear steps, weight, efficiency, maintenance, longevity, price, ease of use, and more. Hopefully, this guide helps you decide which drivetrain is best for your style of riding.

mountain biking

What is a 1X Drivetrain?

The number in 1x, 2x, or 3x refers to the number of chainrings the bike has. Chainrings are the large sprockets toward the font of the bike. The chainrings attach to the cranks.

A 1x drivetrain has one chainring up front and all of the gears in the back on the cassette. The chain stays on the same chainring at all times. This eliminates the need for a front derailleur and shifter. 1x is pronounced ‘one by’.

To make up for the lost gears, 1x drivetrains utilize wide-range cassettes. Most1x drivetrains have a 10, 11, or 12 speed cassette. For example, a bike with a 1×12 drivetrain has 1 chainring in the front and 11 cogs on the cassette in the back for a total of 12 gears.

To compare, 2x drivetrains have two chainrings. One is larger than the other. 3X drivetrains have three different sized chainrings. The innermost chainring is the smallest and the outermost chainring is the largest. A bike with a 2×10 drivetrain has 2 gears in the front and 10 in the back with a total of 20 gears.

A bike with 2 or 3 chainrings requires a front derailleur and shifter to shift between the different chainrings. Most 2x and 3x drivetrains have 9, 10, or 11 gears on the cassette in the back. Older or vintage bikes have anywhere from 2-8 gears in the back.

mountain bike with 1x drivetrain
A mountain bike with a 1x drivetrain

1X Vs 2X Drivetrain

The ideal drivetrain for your bike depends on the type of riding you do, your skill level, your level of fitness, as well as personal preference. In this section, I’ll compare the advantages and disadvantages of 1x vs 2x drivetrains to help you decide.

1x Vs 2x Gear Range

Gear range is the difference between the lowest and highest gear. It is determined by the number of teeth on the smallest and largest chainring(s) and cassette cogs as well as the wheel diameter. Gear range is measured as a percentage. To learn how to calculate gear range, check out this guide.

A lower low gear and a higher high gear is preferable for riding on varied terrain. You can gear down to climb steep hills more easily then shift into your highest gear to travel faster on flat and downhill sections. A bike with a larger gear range typically has a higher top speed as well.

2x and 3x drivetrains offer a wider gear range than 1x drivetrains. For example, a couple of popular multi-chainring drivetrains and their gear ranges include:

  • 2X11 Shimano Deore- 529% gear range
  • 2X10 Shimano XT- 604% gear range
  • 2X12 Shimano XT- 623% gear rang

To compare, a couple of popular 1x drivetrains and their gear ranges include:

  • 1X12 Shimano Deore- 510% gear range with a 10-51 tooth cassette
  • 1X12 SRAM GX- 520% gear range with a 10-52 tooth cassette

As you can see, using a 1x drivetrain does limit your gear range somewhat. On average, a 1x drivetrain has about 15-20% less gear range than a comparable 2x drivetrain. For example, the widest gear range 1x drivetrain is the Sram GX 1×12 with a gear range of 520%. It has a 19% lower gear range than the Shimano XT 2×2 which has a gear range of 623%. This means you’ll have to make a compromise somewhere in your gear range. Either you’ll have a higher low gear or a lower high gear.

Having said this, modern 1x drivetrains are getting closer and closer to 2x and 3x drivetrains in terms of gear range. They achieve this with a wide range cassette with an extra large ‘dinner plate’ gear. It seems like every year wider range cassettes are being introduced with an extra tooth on the largest gear. For example, Sram’s newest 12 speed cassette has a 10-52 tooth range. I imagine the trend will continue as 1x technology improves.

a wide range cassette on a bike
A fat bike with a wide range cassette

A good way to think about gear range to imagine yourself pedaling at a set RPM in your lowest gear then shifting to your highest gear while pedaling at the same RPM. The difference in speed will be 15-20% greater with a 2x or 3x drivetrain because the gear range is wider.

For help calculating the gear range of different cassette and chainring combinations, you can use this tool from Sheldon Brown.

Advantage: 2x and 3x drivetrains

Gear Steps or Jumps

2x drivetrains have smaller steps between gears than 1x drivetrains. In other words, the difference from one gear to the next is smaller. This is possible because 2x and 3x drivetrains have more gears within the gear range than 1x drivetrains. This way, the percentage change from one gear to the next can be lower. The percentage change between gears is determined by the number of teeth on the cassette cogs and chainring(s).

For example, a 2x drivetrain might have a 12% difference from one gear to the next on average. A comparable 1x drivetrain might have a 15% difference from one gear to the next on average.

A few popular cassettes and the average percent change between gears include:

  • Sram 12 speed 10-52t – 15%.
  • Shimano 12 speed 10-51t – 14.6%.
  • Shimano 10 speed 11-36t – 12.7%

Having smaller steps between gears is preferable because it helps you maintain your cadence while shifting through the gear range. Cadence is the number of revolutions your cranks make per minute while you ride. Everyone has an ideal cadence where they pedal the most efficiently. For example, the average cyclist pedals at a cadence of about 60 RPM. Elite cyclists pedal in the 80-120 RPM range.

Ideally, you would maintain a constant cadence regardless of your speed. This isn’t possible with gears because shifting up temporarily reduces your cadence because it becomes harder to pedal. With smaller steps between gears, your cadence won’t slow down as much as you upshift. This way, you spend more time pedaling at your optimal cadence. For this reason, we want the steps between gears to be as small as possible.

For example, with a 1×12 drivetrain with big steps between gears, your cadence might temporarily decrease by 15 RPM when upshifting. On a 2×10 drivetrain with small steps between gears, your cadence might decrease by just 10 RPM. Your cadence will return to the optimal range sooner when the step is smaller. You’ll ride faster and more efficiently this way.

For mountain biking and gravel riding, the larger jumps between gears aren’t as noticeable. Probably because you’re stopping and starting pedaling more often while navigating obstacles off-road. For road riding, the smaller and more consistent the gear steps, the better. It is important to maintain your cadence. For this reason, road riders prefer tight gearing.

A mountain bike with a 3x groupset

As an added benefit, 2x and 3x drivetrains tend to have more consistent gear steps throughout the range. Consistent steps make it easier to maintain your cadence because the difference between gears is more predictable. For example, if you’re running a 3×10 drivetrain, maybe the change between gears is 12% throughout the entire range. With a 1×12 drivetrain, you might have a 12% jump between lower gears, then a 20% jump between gears higher in the range.

For example, on the Sram GX Eagle 50-52 tooth cassette, the step from the 42t gear to the 52t gear is 23.8%. That’s a big jump. When you shift into that gear, your pedaling RPM will decrease significantly. On 1x drivetrains, the lower gears tend to have smaller steps and the larger gears have higher steps.

Advantage: 2x and 3x drivetrains

a cassette adn chain

Efficiency of 1x Vs 2x Drivetrains

2x drivetrains operate more efficiently than 1x drivetrains because there is less friction in the system. VeloNews and CeramicSpeed proved this by performing lab tests on the frictional loss of a 1x and 2x drivetrain.

The test showed that 2x drivetrains lost less energy to friction throughout the entire gear range than 1x drivetrains. On average the 1x drivetrain lost 12.24 watts of power to friction while the 2x drivetrain only lost 9.45 watts of power to friction. That’s a difference of almost 3 watts. This means that 1x drivetrains are about 1% less efficient than 2x drivetrains, on average.

The test also found that the frictional difference between 1x and 2x drivetrains depends on which part of the gear range you’re riding in. When running on the smallest cog, the 1x drivetrain lost 6 watts more power to friction than the 2x drivetrain. That represents a difference of about 2.5%. When running on the largest cog, the difference was only about 1 watt. Even when the chainline was perfectly straight, the 1x drivetrain lost more power to friction than the 2x drivetrain.

The test was performed on two drivetrains with equal gear ranges. The 1x drivetrain used a Sram Force 1 derailleur, 48 tooth chainring, 10-42t cassette, and PC-1170 chain. The 2x drivetrain used a Shimano Ultegra derailleur, 52/39t chainrings, 11-34t cassette, and a CN-HG701 chain. Both chains were stripped of the factory lubricant and re-lubed with mineral oil.

For the test, a machine simulated a cyclist riding with a power output of 250 watts and a cadence of 95 RPM. The testing machine measured the amount of energy that was lost to friction in each gear.

A more efficient 2x drivetrain allows you to travel farther while using the same amount of energy that you would use with a less efficient 1x drivetrain.

The extra resistance in 1x drivetrains is caused by 4 factors:

1. Chain Angle (Chainline)

Ideally, you want your chain to run as straight as possible to minimize friction. 1x drivetrains tend to run the chain at a greater lateral angle from the chainring to the cassette than 2x drivetrains. The greater the angle the chain runs at, the less efficient it becomes. This is the main reason that 1x drivetrains are less efficient than 2x.

When the chain runs at an angle, the chain plates rub against the teeth of the cassette cog and chainring. This creates friction which costs you energy. The chain itself also creates more friction when running at an angle because the plates rub against each other.

a straight chainline
The straighter the chainline, the more efficient your drivetrain will be

There are two reasons that 1x drivetrains tend to run the chain at a greater angle on average than 2x drivetrains. First, the chain stays on the same chainring while stretching between the smallest and largest cassette cogs. While riding in these extreme gears, the chain will be running at a greater angle. This creates friction and sometimes even grinding noises. There is no second chainring you can shift to to help straighten the chainline when using the smallest and largest gears.

1x drivetrains also tend to use slightly wider cassettes. The cassette must be wider to accommodate the extra gears. Most 1x cassettes have 11 or 12 cogs as opposed to 9 or 10 with most 2x drivetrains. For example, a Shimano 9 speed cassette measures 36.5mm wide, and a 12 speed cassette measures 39.5mm. Because the cassette is wider, the chain will run at a more extreme angle when using the smallest and largest cogs.

2X drivetrains maintain a straighter chainline, which produces less friction. You can shift from one chainring to the other to move the chain so it is better lined up with the cog that you’re using. For example, when using your larger innermost cassette cogs, you can shift to your smaller innermost chainring. This will result in a better chainline and less friction. The cassette is typically a few millimeters more narrow because 2x drivetrains tend to have fewer cogs. This way, the chain doesn’t run at as extreme of angle when using on the smallest and largest cogs. In addition,

The chainline problem is the reason that 1x drivetrains only recently became popular. Modern technology allowed manufacturers to design extra narrow 11 and 12 speed chains that can run at an angle. These chains are also more narrow. This allows the cassette cogs to be more narrow because they can sit closer together. Without these advanced chains, wide-range 1x drivetrains wouldn’t be possible.

2. Chain Tension

1x drivetrains run the chain at a higher tension than 2x drivetrians. The main reason is that the chainring is typically smaller. Running the chain at a higher tension helps to prevent chain drops.

When the chain runs at a higher tension, the chain plates pull harder on the pins where they pivot. This creates more friction. Additionally, the higher tension on the chain pushes the rollers against the teeth of the cogs and chainring harder. This also causes more friction. The additional friction costs you energy.

3. Link Articulation

1x drivetrains use smaller chainrings and cogs than 2x drivetrains. This results in more chain articulation or folding. Chain articulation is the number of degrees the chain has to hinge to contact each tooth on the cog and chainring. In other words, the chain must bend more to move around smaller gears. When the chain articulates, energy is lost to friction. The more the chain articulates and the more energy is lost.

4. Chain Speed

Whenever the chain interacts with the gear teeth, it causes friction. Because 1x drivetrains tend to use a smaller chainrings and cogs, the chain must run at a higher speed. When the chain moves faster, it has more tooth interactions per mintue. The more tooth interactions that occur, the more friction is introduced into the system.

A Few More Drivetrain Efficiency Factors to Consider.

  • The quality of the chain- Higher end chains create less friction. In general, Shimano chains tend to create less friction than Sram chains.
  • Jockey wheel size- Larger jockey wheels cause less resistance because the chain doesn’t have to articulate as much. The jockey wheel bearings can also cause friction if they aren’t properly lubed.
  • Aerodynamics- 1x drivetrains are more aerodynamic because they don’t have a front derailleur, shifter, and one less chainring. Wind tunnel testing showed that this saved about 3 watts at 30 mph. Even with the aerodynamic gain, the extra friction of riding in a high gear still makes 1x drivetrains less efficient than 2x.
  • Weight- 1x drivetrains are lighter because they don’t have a front derailleur, shifter, shifter cable, and one less chainring. This does help improve efficiency. Even with the extra weight factored in, 2x drivetrains are more efficient.

A Note About Cross Chaining

On some 2x and 3x drivetrains, you do have to be careful not to cross chain. Cross chaining means using the big chainring and big cassette cog or the small chainring and small cassette cog. This puts your chain at an extreme angle which creates friction. It is also hard on components.

During the test, it was found that the 2x drivetrain became less efficient than the 1x when using the inner chainring and either of the smallest three cassette cogs. Cross chaining isn’t possible on 1x drivetrains.

For more info, check out this article about cross chaining from wickwerks.com.

Advantage: 2x drivetrains

Drivetrain Weight

1x drivetrains are lighter than 2x drivetrains, as you would expect. A lighter bike allows you to accelerate and climb faster and maneuver more easily simply because you’re moving less mass around as you ride. Lighter bikes are preferable across all categories of cycling.

1x drivetrains are lighter because there are simply fewer components. For example, running a single chainring eliminates the need for a front derailleur, front shifter, shfiter cable, and the extra chainring. The heaviest components that you’re eliminating are the front derailleur and extra chainring.

How Much Lighter is a 1x Drivetrain?

On average, a 1x drivetrain weighs 250-450 grams less than a comparable 2x drivetrain. That represents a weight savings of about 10-20% when you switch from a 2x to 1x drivetrain.

For example, the Sram Eagle 1x drivetrain weighs 1973 grams. The Shimano Shimano SLX 2x drivetrain weighs 2400 grams. That’s a difference of 427 grams. For some more road and gravel groupset weight comparisons, check out this list.

A front derailleur weighs roughly 100-200 grams depending on the brand and quality. A double chainring crankset weighs around 50-100 grams more than a single chainring crankset. A front shifter and cable add a few extra grams as well.

If you’re using the lightest possible components, a 2x drivetrain with carbon chainrings and high-end ultralight front derailleur and shifter would still weigh around 120 grams more than a 1x drivetrain. If weight is an important factor to you, single chainring is the way to go.

The weight difference between 2x and 3x drivetrains is minimal. Really, the only difference is the extra chainring which weighs around 50 grams give or take.

For most riders, it’s probably not worth getting a new drivetrain to save 250 grams or so. The weight difference is pretty insignificant. For a comparison, a 500ml bottle of water weighs 500 grams.

Advantage: 1x

Shifting and Ease of Use

Maybe the biggest advantage of 1x drivetrains is the simplicity. A single chainring makes shifting easier because you don’t have to think about where you are in the gear range. You also don’t have to think about which chainring you’re using. When you want to speed up, you shift up. When you want to slow down, you shift down. It takes very little thought. This way, you spend less time worrying about shifting or choosing the correct gear and more time focusing on riding and enjoying the view.

There are also fewer controls on the handlebars. You just use one hand for shifting. This is great for new riders who haven’t mastered shifting yet. It’s one less thing to think about while riding. You don’t have to remember which shifter to use or which chainring you’re on.

When using a 2x or 3x drivetrain, it’s almost overwhelming to have 20-30 gears to choose from. You might not know which chainring you should use for the given terrain and grade or when to shift from one chainring to the other. It can also be a bit confusing dealing with so many gears. You never know exactly where you are in the gear range. You can easily cross-chain if you’re not paying attention.

1x bikes only need one shifter

Another benefit of 1x drivetrains is that they free up some space on your handlebars because you don’t need two shifters. This gives you space for a dropper seat lever or other accessories like a cycling computer, phone moung, GPS, bell, or whatever else you care to mount on your handlebars. Of course, there is less maintenance as well because there are fewer components.

Advantage: 1x

Parts Availability and Compatibility

Parts availability depends on where in the world you ride. Generally, 2x and 3x drivetrain components are easier to find than 1x drivetrain components. There are a couple of reasons for this. 1x drivetrains are newer so they haven’t become common or popular in some parts of the world. They are also and more expensive. 1x bikes and parts just aren’t available in many poor countries, developing countries, and remote regions because there is no demand.

For bicycle tourists and bikepackers who ride in the developing world or remote regions, the ability to find spare parts is an important consideration when choosing components. When a drivetrain component like a chain or cassette wears out or a derailleur or shifter breaks, you need to be able to find a replacement. It will be nearly impossible to find a clutch rear derailleur or 12 speed cassette in a village in West Africa or Central Asia.

Many bicycle tourists and bikepackers use 2x or 3x chainring drivetrains with 8 or 9 cog cassettes because these sizes have been standard for many years. Chains, shifters, and derailleurs are usually cross-compatible as well. Components can be found in pretty much every country. In most parts of the world, you can even find 2x parts in small town bike shops and in remote villages.

When riding through a remote region, you need to be able to find repla

These days, 10 speed components are becoming pretty common. Most developing countries have high-end bike shops in the capital that sell mountain bikes equipped with 10 speed and even 11 speed drivetrains. They stock replacement parts as well.

12 speed drivetrain parts are hard to find in much of the world. Bike shops in developing countries and rural regions generally don’t carry 12 speed chains and cassettes or clutch rear derailleurs. In addition, 12 speed drivetrains often don’t allow you to mix and match between brands and components aren’t cross-compatible. For example, Sram 12 speed chains have large rollers that are designed to fit on their cassettes. You can’t really use a Shimano 12 speed chain. This further limits your options.

If a part wears out and you can’t find a replacement locally, you may have to wait for parts to be shipped in or fly to a nearby country to buy what you need. Parts availability is probably the biggest argument against using a 1x drivetrain for touring. Of course, this will change in the future as wide range 1x 12 drivetrains become more common. Globalization is also making it easier to get parts shipped to remote destinations when you need them.

If you only ride in developed regions like North America, Western Europe, Australia, Japan, etc, you don’t really have to worry about parts availability. You can go to any bike shop and buy whatever you need. If they don’t have it in stock, chances are they can order it and get it to you in a couple of days.

Advantage: 2x and 3x

1x Vs 2x Drivetrain Longevity

How long your drivetrain lasts depends on a number of factors including the number of speeds, the quality of the components, and how well you maintain it. Generally, 1x drivetrains last longer than 2x. In this section, I’ll explain why.

Chain Longevity

You may assume that the wider chains used on 8, 9, 10, and 11 speed drivetrains would be more durable than the narrow chains used on 12 speed drivetrains. After all, they have more material and feel more substantial. Surprisingly, this isn’t the case. For this reason, 1x drivetrains tend to last longer than 2x drivetrains.

Zero Friction Cycling performed extensive testing to find the longevity of various chains and found that 12 speed chains are the most durable and long-lasting chains in use today. In fact, 12 speed chains last substantially longer than 8, 9, 10, and 11 speed chains. Strangely, the more gears, the longer a chain lasts. For example, during tests, 12 speed chains lasted up from 3800km to 6800km. 11 speed chains lasted around 3000km on average. 9 Speed Shimano chains lasted around 2000km.

It’s not completely clear why 12 speed chains last so much longer. There may be a number of factors at play. Precision material engineering has improved. The metals are harder. Chemical coatings are applied to reduce friction. Chain designs have been updated as well.

The test was performed on 31 chains from 8-12 speed from multiple manufactueres. The test controlled lubrication and contamination. During the test, the chains were run at 90rpm with 250 watts of resistance until they showed 0.5% elongation wear. The test was stopped 0.5% wear because this is when 12 speed chains begin causing excessive wear to your cassette and chainring.

It’s important to note that you can run 8, 9, and 10 speed chains until they reach 0.75% elongation wear as opposed to 0.5% for 11 and 12 speed chains. Chains also do not wear in a linear manner. They wear slowly when they are new and continue to wear at an increasing rate throughout their life. For this reason, 8, 9, or 10 speed chain can be run about 10-20% longer than they were in the test. This makes up for some of the difference in chain longevity. Having said that, 11 and 12 speed chains still last significantly longer.

Cassette and Chainring Longevity

When you chain starts to stretch from wear, it starts causing wear on your cassette and chainring(s). 11 and 12 speed chains should be replaced when they reach 0.5% wear. 8, 9, and 10 speed chains should be replaced when they reach 0.75% wear.

As a rule of thumb, a cassette lasts as long as 3 chains. Because you can use 1×12 speed chains longer than 8, 9, 10, and 11 speed chains, you’ll get more mileage out of each cassette. For example, if a 12 speed chain lasts 500km longer than a comparable 10 speed chain, you’ll get an extra 1500km out of each cassette.

You should go through around 6 chains for every chainring. 12 speed chainrings last longer as well because the chains last longer. Having said that, you’ll need to replace the chainrings on 2x and 3x bikes less frequently because they share the wear between 2 or 3 chainrings. With a 1x bike, you’re always riding on the same ring.

Maintenance plays a major role in the longevity of your drivetrain as well. If you let your chain get dirty and dry, it will wear out and fail much faster. A dirty chain will cause your cassette and chainring to wear quicker as well because the dirt creates more friction. Riding with a worn out chain also causes your cassette and chainring to wear out prematurely because the chain links don’t light up with the gear teeth properly. Regardless of which type of drivetrain you use, you’ll want to clean and lube it frequently to keep everything running smoothly and efficiently.

Advantage: 1x

Price

The price of drivetrains really comes down to the quality of components you run and their longevity. As a rule of thumb, you’ll have to replace your cassette every 3 chains and your chainring every 6 chains. You should replace an 11 or 12 speed chain when it reaches 0.5% wear. You should replace an 8, 9, or 10 speed chain when it reaches 0.75-1% wear.

If you’re on a tight budget, you’re better off going with a 2x or 3x drivetrain. Even though the components don’t last as long (as outlined above), they are still cheaper to run than 1x drivetrains because chains, cassettes, and chainrings are cheaper. Parts are cheaper because have been around longer and they are less technologically advanced. For example, a 9 speed chain costs around $15-$25 while a 12 speed chain costs $30-$60. 12 speed cassette start at around $100. 10 speed cassettes start at around $50.

Zero Friction Cycling calculated the cost to run a number of different drivetrains for 10,000km. A couple of examples include:

  • 1×12 Sram GX Eagle- around $1700 per 10,000km.
  • 1×12 Shimano XTR- around $1050 per 10,000km.
  • 3×9 Shimano Deore- around $700 per 10,000km.
  • 2×10 Shimano Ultegra- around $550 per 10,000km.

These costs include chains, cassettes, and chainrings. As you can see, bikes with multiple chainrings tend to cost less to run, even though you’ll go through more chains, cassettes, and chainrings.

When it comes to buying the whole groupset, 1x models tend to cost a bit more than 2x and 3x models, even though they have fewer components. This is probably because the technology is newer and more advanced. Expect to spend an extra $50-$100 for a 1x groupset than a comparable 2x groupset.

Advantage: 2x and 3x

Frame Geometry, Tire Clearance, and Suspension

1x drivetrains allow for a more favorable frame geometry and more tire clearance than 2x. The reason is that 1x drivetrains allow bikes to have shorter chainstays because the chainline won’t interfere with the rear tire. 2x drivetrains, on the other hand, require longer chainstays so the chain doesn’t rub the tire when using the innermost chainring. Mountain bikers generally prefer shorter chainstays. This design makes the bike more easily maneuverable. It is also easier to lift the front wheel over obstacles when the chainstays are shorter.

For this same reason, you can usually run wider, higher volume tires on 1x bikes. There is more clearance between the tire and chain. On 2x and 3x bikes, the chain can rub the tire when using the innermost chainring if your tires are too wide.

Frame pivot locations on full suspension bikes are less limited as well with a 1x drivetrain. On some suspension bikes, the frame pivot location can be limited by the front derailleur. Framebuilders have to keep the front derailleur location and mounting point in mind when designing the frame. 1X drivetrains eliminate this issue and allow for better full suspension bike frame designs. For this reason, pretty much every new full suspension bike comes equipped with a 1x drivetrain.

Advantage: 1x

Chain Drops

1x drivetrains tend to offer better chain security. The chain always stays fixed on the same chainring. Most 1x drivetrains also have clutch derailleurs. These increase chain security by keeping the chain tentioned at all times. This way, the chain doesn’t bounce around when you ride over rough surfaces.

With 2x and 3x drivetrains, chains occasionally slip off when shifting from one chainring to the other. If the derailleur limits aren’t set right, the derailleur can push the chain right off. Chains also tend to drop on rough roads because they bounce around.

Having said that, modern 2x drivetrains are available with clutch rear derailleurs. Chain drops are pretty rare as long as the front derailleur is properly adjusted.

Advantage: 1x

Maintenance and Repairs

A major benefit of 1x drivetrains is the mechanical simplicity. There is no front derailleur or shifter to set up, adjust, and maintain. You only have to deal with tuning the rear derailleur. There are also fewer parts that could fail while you’re out riding in the middle of nowhere. Cleaning the drivetrain is easier as well. With a 1x drivetrain, there are fewer places for mud or snow to build up.

In addition, you won’t have to replace your chain, cassette, or chainring as often because 12 speed chains last longer than 8, 9, 10, and 11 speed chains. You might be able to ride 300-800km further before you need to replace any parts. This way, you can spend more time riding and less time working on your bike.

Advantage: 1x

Performance and Number of Gears

Some cyclists find that 2x drivetrains offer better performance than 1x drivetrains. With a 2x drivetrain, you may be able to maintain a higher average speed or ride further without tiring out.

One potential reason is that 2x drivetrains offer more gears. With more gears, you have a better chance of finding the ideal gear for the conditions you’re riding in. The ideal gear depends on a number of factors including the type of surface you’re riding on, the incline, and your level of fitness. For example, when you have 20-30 gears to choose from, you can dial in the exact gearing you need for whatever situation you’re in. When you ride in the correct gear, you don’t waste energy pedaling too hard or spinning too fast.

With a 1x drivetrain, sometimes you can’t find the perfect gear. Because there are only 10-12 gears, the step from one gear to the next might be too great. If you shift down, you may end up riding at a higher cadence than you needed to. You’ll end up burning more energy. When you’re speeding down a hill, you may not have a gear that is high enough so that you can pedal. In this case, your gearing is too low. Occasionally, you may just wish you had another higher or lower gear.

Having said this, double chainring drivetrains don’t have as many more gears as it may appear. There are two reasons for this. First, some gears may be duplicates. If you count the teeth, you may find that more than one combination of your chainrings and cassette has the same gear ratio. It is common to have 2 or 3 duplicate gears in a 2x or 3x drivetrain.

Most professional road and mountain bikers still use 2x drivetrains

In addition, when using multiple chainrings, oftentimes two of the gears are not usable. These are the gears that put your chain at an extreme angle. For example, you often can’t use your smallest rear cog and smallest chainring or your largest rear cog and largest chainring. This is called cross chaining.

A 2×10 drivetrain has 20 speeds but only 16 or 17 of those may be unique and usable. Most modern 1x drivetrains have 11 or 12 gears these days, all of which are different and usable.

Realistically a 2x drivetrain gets you only 4-6 extra gears. These extra gears help to expand the gear range and reduce the difference between gears but the difference isn’t as substantial as it may seem when you initially compare 1x vs 2x drivetrains.

2x drivetrains usually offer a wider gear range with a lower low or a higher high gear than 1x. A wider gear range allows you to efficiently ride a wider variety of terrain and inclines. In addition, 2x usually offers smaller steps between gears. When you have 20-30 gears, the next gear down might be just a few gear inches different. You can shift almost seamlessly when the difference between gears is small. This helps you maintain your pedaling rhythm while cycling at a high cadence. This way, you don’t waste energy regaining your cadence after shifting. There is also less friction in the drive system. Because the chain runs at a less extreme angle, it creates less friction. This allows the chain to transfers power more efficiently. All of this helps to improve your performance.

Advantage: 2x

Technology and Trends

1x drivetrains are a newer and more advanced technology. Narrow and flexible chains allow for a simple, easy to use, and low maintenance drivetrain. As the technology improves I imagine manufacturers will find a way to make 1x drivetrains with even thinner chains, more gears, and larger gear ranges. A lot of research and development is going into improving 1x drivetrain technology.

These days, most mid-range to high-end mountain bikes, bikepacking bikes, and touring bikes come with 1x drivetrains. Particularly if they use Sram components. In fact, all of Sram’s mid-range and high-end off-road groupsets are 1x at this point. Shimano seems to be following the trend. If you’re the type of rider who likes to use the newest and most advanced gear, 1x drivetrains are in right now.

Double and triple-chainring drivetrains, on the other hand, are a tried and true technology. They have been standard for decades at this point. They have been tested in racing and ridden around the world. The technology may not be quite as advanced or modern, but it is reliable and efficient. For this reason, older 8, 9, and 10 speed 2x and 3x drivetrains are a popular choice for bicycle touring in remote parts of the world.

Looks

Many riders prefer the looks of a 1x drivetrain. The reason is that it looks cleaner, simpler, and less complex. There is no front derailleur, shifter, or front cable and there is a single chainring. Compared to a 2x bike, the system just looks a bit prettier and simpler. Having said that, some cyclists don’t like the look of the massive ‘dinner plate’ cassette cog in 1x drivetrains. Looks are subjective, after all.

1x drivetrain on fat bike
A fat bike with a 1x drivetrain

1X Drivetrain Pros and Cons

Pros

  • Lighter- Because 1x drivetrains don’t have a front derailleur, front shifter, and one less chainring, they weigh 250-450 grams less than 1x drivetrains.
  • Easier to use- There is only one shifter to work. When you want to speed up, you shift up. When you want to slow down, you shift down.
  • Longer lasting- 11 and 12 speed chains are more durable than 8, 9, and 10 speed chains. 1x chains, cassettes, and chainrings last longer as a result.
  • Less frequent maintenance- Because chains, cassettes, and chainrings last longer, you don’t have to replace them as often.
  • Better frame geometry- 1x drivetrains allow for shorter chainstays. There are better rear suspension options because there is no front derailleur in the way.
  • More tire clearance- The chain won’t interfere with the tire because it sits further from the frame.
  • More technologically advanced- A lot of research and development is going into designing better 1x drivetrains. already most high-end mountain and touring bikes use 1x
  • Fewer chain drops- 1x drivetrains use a clutch derailleur and run the chain at higher tension so the chain stays more secure.
  • Better looking- 1x drivetrains look cleaner and simpler because they remove the front derailleur shifter, cable, and a chainring.

Cons

  • Less efficient- 1x drivetrains run the chain at a greater angle, higher speed, and at higher tension. This causes more friction. 1x loses about 3 watts more power to friction than 2x.
  • Less gear range- Current 1x drivetrains max out at 520% gear range.
  • Larger and less consistent steps between gears– Because there are fewer gears, the percent change from one gear to the next is larger. Most 1x drivetrains have a 14-15% change between gears. This makes it harder to maintain your cadence when shifting.
  • Parts availability can be poor- In the developing world, it can be hard to find 1x components because 1x bikes aren’t as common.
  • More expensive- Because 1x groupsets are newer and more modern, they cost about $50-$100 more than comparable 2x groupsets.
  • Your performance might suffer- Sometimes you can’t find the right gear. The gear steps can throw your cadence off. The extra friction can slow you down. You may maintain a lower average speed with 1x.

2x Drivetrain Pros and Cons

Pros

  • More efficient- 2x drivetrains maintain a straighter chainline so there is less friction in the system. On average, a 2x drivetrain is 1% more efficient than 1x.
  • Wider gear range- 2x drivetrains can have over 600% gear range.
  • Smaller and more consistent steps between gears- Because there are more gears in the range, the percent change from one to the next can be smaller. Most 2x drivetrains have an average of 12-13% change between gears. This makes it easier to maintain your cadence.
  • Better parts availability- 2x components are easier to find in the developing world as well as rural regions. They tend to offer better cross-compatibility between brands as well.
  • Cheaper- 8, 9, and 10 speed chains, cassettes, and chainrings are cheaper than 11 and 12 speed components. For this reason, 2x costs less to maintain.
  • Better performance– Because 2x drivetrains have more gears, more gear range, and less friction, you can maintain a higher average speed and ride further without tiring out
  • 2x drivetrains are a tried and true technology- They have been on the market for many decades.

Cons

  • Heavier- 2x drivetrains require a front derailleur, second chainring, and front shifter which add weight.
  • Harder to use- You have to remember which chainring you’re on so you don’t cross-chain. There are also two shifters to work.
  • Less durable- 2x chains wear out faster than 1x chains. You’ll have to replace the chain, cassette, and chainrings more often.
  • More frequent maintenance required- Because chains, cassettes, and chainrings don’t last as long, you have to replace them more frequently.
  • Less tire clearance- 2x chainlines can interfere with the rear tire. This can also limit minimum chainstay length.
  • More chain drops- Chains can slip off when shifting between chainrings.

A Note About Shimano Vs Sram 1x and 2x Drivetrains

There are a number of drivetrain manufacturers but the two most common by far are Shimano and Sram. Both brands offer excellent 1x and 2x drivetrains and have loyal followers. Most differences between the two come down to personal preference. In some cases, one has an advantage over the other. In this section, I’ll outline a few key differences to help you decide.

The most significant difference between Shimano and Sram drivetrains is the shifting actuation. This is a ratio that compares the difference between the movement of the derailleur and the movement of the shifter lever. Shimano uses around a 1:1 ratio on most of their setups. With Shimano, the derailleur moves further. Some riders claim that this makes the shifting feel more robust and crisp, which encourages confidence while riding rough terrain.

Sram, on the other hand, uses a 2:1 ratio on most of their setups. The benefit to this is that shifting is smoother and takes less force. Some riders prefer this but others find that there isn’t enough feedback from each shift, which can lead to unintended shifts. Sram shifters also make a loud click when you shift gears. This can help to improve feedback.

Another major difference is the design of the shifters. Shimano uses trigger shifters that can be manipulated with your thumb and index finger. Sram uses Grip Shift across their range. This popular system allows you to move across the gear range by twisting part of the grip. Sram also offers trigger shifters if you prefer. The difference is theirs are only thumb operated. Again, this mostly comes down to personal preference.

There are a number of other minor differences as well. Shimano allows you to upshift two gears at a time. Sram only allows you to shift up one gear at a time. both systems allow you to shift through multiple gears while downshifting. Shimano drivetrains tend to make it easier to replace derailleur cables because the housing is easier to access. Sram rear derailleurs can lock in place. This removes tension from the chain so you can easily remove the rear wheel.

Sram and Shimano Groupset Lineup

At this point, Sram has pretty much committed to 1x drivetrains in their off road lineup. They only offer a handful of 2x drivetrains in the lower end range. All of their mid-range to higher end options are 1x. Sram tends to be one of the first to the market with newer technologies. They are a bit more progressive in this respect.

Sram Mountain Lineup
  • Entry Level– X5, X7, and X9 (2×10 drivetrains)
  • Mid-Range– NX (1×11), NX Eagle (1×12), GX (1×11), GX Eagle (1×12)
  • High-End- XO (10 speed), XO1 (1×11), XO Eagle (1×12), XX (10 speed), XX1 Eagle (1×11), XX Eagle (1×12), Eagle AXS (wireless electronic shifting)
Shimano Mountain Lineup

Shimano offers 1/2/3x drivetrain options across their mid-range to high end lineup. At the lower end, they offer 2x and 3x options. Shimano tends to take a bit longer to introduce newer technologies to their lineup. The company is a bit more conservative. They like to perfect new technologies before releasing them.

  • Entry Level- Alivio and Deore 2/3×10 groupsets. Deore is the slightly higher end of the two
  • Mid-Range- SLX M7100 (1/2/3×12) and Deore XT M8100 (1/2/3×12). Shimano just moved to 12 speed last year.
  • High-End- XTR M9100 (1/2×12), XTR Di2 M9050 (1/2/3×11). (Di2 is Shimano’s electronic shifting system.)

1x Groupsets for Road Riding

Most road riders still prefer 2x drivetrains but that may begin changing in the near future. Both Shimano and Sram offer 1x compatible road options as well.

Shimano’s Ultegra line can be converted to 1x by replacing the chainrings with a single 1x chainring. Shimano also offers the GRX RX810 1×11 groupset which is designed specifically for gravel use.

Sram’s Force, Rival, and Apex road groupsets are all available in 1x versions. Sram also offers the eTap AXS and Red eTap AXS road groupsets with electric shifting. They are available in 1×12 and 2×12 versions.

A Note About the Future of Drivetrains: Electronic Shifting

As the name suggests, electronic shifting operates the derailleur(s) with electricity rather than mechanically with a cable. Both Sram and Shimano have introduced electronic shifting into their lineup. Both systems take a slightly different approach.

Shimano’s electronic shifting system is called DI2 (Digital Integrated Intelligence). DI2 groupsets are available in 1/2/3 x 11 versions. The 1x version has an electronic rear derailleur with a wire that runs to the shifters. The 2x and 3x versions have an electronic front derailleur. The shifters are simple buttons. They are available in both road and mountain groupsets. The road groupset is the XTR M9050 and the road version is Ultegra R8050.

The multi chainring versions offer ‘Syncro Shift’ mode. This high tech system is designed to give you the simplicity of a 1x drivetrain with the gear range and efficiency of a 2x system. Syncro Shift allows the front and rear derailleurs to communicate. The front derailleur shifts automatically based on the gear you’ve chosen for the rear derailleur. This way, you’re always using the ideal chainring.

Sram’s electronic shifting system is called AXS. They are available in both road and mountain versions. The mountain version is called the Eagle AXS. It is only available in 1×12. The road version is called eTap AXS and Red eTap AXS. It is available in both 1×12 and 2×12 versions. Sram’s electronic groupsets are controlled wirelessly with simple buttons that mount on the handlebars. The 2x versions offer ‘Sequential’ mode which works like Shimano’s Synchro Shift.

Electronic shifting offer several benefits over mechanical cable shifting. The main benefits include faster and more precise shifting, less maintenance, and less chain rub. You can also mount multiple shifters around your handlebars because the shifters are simple buttons. This allows you to easily shift no matter which position you’re riding in.

Of course, there are drawbacks. The biggest one being that you have to charge the batteries. If they go dead, you’re stuck shifting manually until you can charge them up. Electronic shift systems are also pretty expensive.

For more info, check out my guides:

Switching from a 2x to 1x Drivetrain

This is an easy conversion to make. It basically involves swapping out a few 2x parts for 1x parts. Exactly which parts you need to replace depends on your current drivetrain.

In most cases, you’ll need a new chainring, cassette, and chain. In some cases, you can get away with just installing a new 1x chainring. This would be the case if you’re running a 2×11 drivetrain. If you’re currently running an older 3x drivetrain, you may also need a new crankset and rear derailleur.

The one part that you absolutely must replace when switching from 2x to 1x is the chainring. You can’t just remove the small chainring from your 2x setup and run the large one. The reason is the 1x chainrings have been specially designed to hold the chain on and prevent it from dropping. They are called ‘narrow wide’ chainrings. The teeth alternate between narrow and wide. This way, they mesh with the narrow and wide links of the chain. This prevents chain drops. This is necessary because 1x bikes don’t have a front derailleur to guide the chain back into place if it tries to come off.

2x chainrings have a profile that allows for gear changes. If the chain slips off, the front derailleur is there to catch it and guide it back on. Because you won’t have a front derailleur after making the conversion, you would experience more chain drops if you reused one of your old 2x chainrings. When installing your new chainring, you may need to use some spacers to position it in the middle to ensure a straight chainline.

If you’re running a smaller range 8, 9, or 10 speed cassette, you may want to swap it out for a wider range 11 or 12 speed model. This isn’t required but you’ll be giving up too much gear range if don’t replace it. After all, the whole point of going 1x is to have a similar gear range with less complexity.

If you replace the cassette to a model with more gears, you’ll probably have to replace your chain as well. Your new chain needs to be compatible with the number of gears on your new cassette. For example, if you’re installing an 11 speed cassette, you’ll need an 11 speed chain.

In many cases, you’ll have to replace the rear derailleur as well. Usually, rear derailleurs are designed to work with cassettes with a specific range of speeds. If you’re replacing your 9 speed cassette with an 11 speed model when you make the conversion, your rear derailleur probably won’t be compatible. You will need to replace it with an 11 speed rear derailleur. When buying a new rear derailleur for a 1x mountain bike setup, consider buying a clutch rear derailleur. These keep the chain taught. This greatly reduces chain drops. They also prevent the chain from slapping around while riding bumpy terrain.

One part you shouldn’t have to replace is the rear hub. Mountain bike hubs are designed to fit 8, 9, 10, 11, and 12 speed cassettes.

Another Drivetrain Option: Internal Gear Hubs

If you want to ditch derailleurs altogether, you might consider switching to an internal gear hub. These are an alternative to derailleurs which change the bike’s gear ratio with planetary gears that are sealed inside of the rear hub. Most setups use a single chainring with anywhere from 2-14 gears in the hub.

Internal gear hubs offer a number of benefits over derailleurs. First, they require less maintenance. Reliability is superior as well. Because the unit is sealed, you don’t have to worry about contaminants entering and causing damage. There is no derailleur to adjust or break. Chains also last longer because the chainline always perfectly straight. Another major benefit is the fact that you can shift internal gear hubs while they are stopped and you can shift multiple gears at once. The rear wheel is also stronger due to the larger hub size.

Of course, there are some drawbacks to internal gear hubs. To start off, they are 2%-10% less efficient than derailleurs because the power transfers between more gears on its way from the pedals to the rear wheel. Next, they have less gear range and fewer gears than a 2x drivetrain. Another major drawback is that internal gear hubs aren’t user-serviceable.

For more info, check out my derailleur vs internal gear hub pros and cons list.

A Bit of 1x Drivetrain History

There has always been a demand for 1x drivetrains but they weren’t always available off the shelf. The technology just wasn’t there for manufactures to make reliable and efficient wide-range 1x drivetrains until recently.

Before mass-market 1x drivetrains existed, cyclists used to make their own by cobbling together different components. These setups were often unreliable. Chains frequently dropped. Gears missed. There wasn’t enough gear range available.

In 2012, Sram released the first mass-market 1x drivetrain. This was made possible by 3 technological advancements including:

  • Wide/narrow chainrings- These guide the chain so it meshes with the chainring’s teeth. The teeth match the inner and outer plates of the chain. Before this technology existed, dropped chains were more common while pedaling at high RPMs, shifting, or riding over rough surfaces. Wide/narrow chainrings were invented in the 70s. They do not increase friction.
  • Clutch rear derailleurs- These hold the chain at tension so it doesn’t bounce around while riding over rough surfaces. This helps to prevent the chain from slapping around or bouncing off the cassette.
  • Wide-range cassettes- Modern cassettes offer up to 12 speeds with 10-52 tooth cogs. Ten years ago, most mountain bikes came with 9 speed cassettes with 11-32 tooth cogs. Modern wide range cassettes offer over 500% of gear range which is plenty for most riders.

Since they were introduced 8 years ago, 1x drivetrains have greatly increased in popularity. Almost 100% of new mountain bikes come equipped with a 1x drivetrain these days. The majority of touring and bikepacking bikes also use 1x. Sram only offers 1x drivetrains in their high-end off-road range of groupsets. Shimano offers 1x drivetrains through their mid and high-end range or groupsets.

Final Thoughts About 1x Vs 2x Drivetrains

This choice really comes down to your style of riding. 2x drivetrains are an excellent choice for those who ride a wide range of surfaces and grades. Road riders also prefer 2x drivetrains because the steps between gears are smaller. The efficiency of a straighter chainline is a nice bonus as well.

If you can make do with larger steps between gears and a slightly smaller gear range1x drivetrains are an excellent option. They offer ease of use and simplicity that is hard to beat. The longevity of 12 speed chains is a nice plus as well.

As bike drivetrain technology advances, I expect to see 1x gear ranges continue to improve and the number of gears continue to increase. Cycling companies are always trying to outdo each other to give their racers an edge. Fortunately, casual cyclists like me get to benefit from the technology as well. For mountain bikes and gravel bikes, 1x is already becoming the standard. I wouldn’t be surprised if more road cyclists didn’t start switching to 1x too.

Where do you stand on the 1x vs 2x drivetrain debate? Share your experience in the comments below!

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Alex

Saturday 5th of June 2021

Thank you for this excellent article! I would like to suggest a correction regarding the statement "Because 1x drivetrains tend to use a smaller chainrings and cogs, the chain must run at a higher speed." Actually, the opposite is the case: The smaller the chainring, the lower the chain speed.

Jim

Monday 22nd of March 2021

Not sure how this can be a February 2021 article since SRAM has not had X5, X7, etc. models for some time. These older SRAM models have been replaced with a flattened model line-up a couple years ago. Also, grip shifts have been uncommon on their setups for quite some time as well and mostly seen only on box store level bikes.

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