Chainstays: The tubes running from the bottom bracket shell to the rear dropouts. The name comes from the proximity of the chainstays to the chain.
FAQ: How are chainstays measured? The chainstays are measured from the center of the bottom bracket to the middle of the rear axle.
The length of the chainstays can have a tremendous impact on a bike’s handling.
Bike engineers and designers manipulate it according to the style of riding that a bicycle is designed for.
What Are The Benefits of Short Chainstays?
For quite a while the bike industry has been pushing the idea of shorter chainstays for the following reasons:
1. Shorter Wheelbase
Wheelbase: The distance between the front and rear axle.
Shorter chainstays effectively reduce the wheelbase of the bicycle. The result is a nimbler, more maneuverable machine offering faster cornering – a good quality when the trails are extra “twisty”.
The improvement comes at a price – reduced stability and potential lifting of the front wheel during climbing.
2. Short Chainstays Compliment Tricks
The shorter the chainstays, the closer the rear wheel is to you, and the easier it is to get your weight behind it which is what happens during tricks like bunny hops, wheelies, manuals, and drops.
For that reason, BMXs, dirt jumpers, and free ride bikes have short chainstays.
For example, the chainstays of BMX bikes intended for street riding start around 12.5 inches or 317.5 millimeters whereas BMXs intended for trail riding have a bit longer chainstays – over 13.75 inches or 349 millimeters.
And since the machines listed above are not designed for distance or climbing, the riders experience primarily positives from the short chainstays.
The favorable weight distribution isn’t the only benefit of shorter chainstays when performing stunts. Another positive trait is the smaller, stiffer, and more “obedient” frame.
3. Improved Rear Wheel Traction
Shorter chainstays bring the rear wheel towards the rider. As a consequence, the part of the tire in contact with the ground gets closer to the cyclist’s center of gravity.
The tire gets more “squished” because it supports more of the rider’s weight. Subsequently, the size of the tire’s contact patch with the ground increases without a reduction in air pressure.
The result is increased rear wheel traction which is very helpful on tough terrain.
Shorter chainstays are also beneficial when climbing out of the saddle because they maximize the traction of the rear wheel as much as possible and minimize the risk of annoying rear-wheel slipping.
For the same reason, many characterize single-speed bicycles with short chainstays as more efficient climbers than their long chainstay brothers.
4. Shorter Chainstays Are Lighter and Stiffer
Shorter chainstays require less tubing and are therefore lighter and stiffer. The extra stiffness results in a more efficient transfer of power from the pedals to the rear wheel and is considered beneficial to the drivetrain.
Having said that, the effect of this feature is difficult to measure due to the high number of other factors (cassette, cranks, bottom bracket, the material and design of the frame…etc.) influencing the drivetrain’s performance.
But since grams matter in the world of cycling, the weight saving gains are worth mentioning even though their value is marginal, especially to recreational cyclists.
What Are The Downsides of Short Chainstays?
1. Imbalanced geometry
An unhealthy pursuit of short chainstays could result in weird and unbalanced geometry putting too much of the rider’s bodyweight close to the rear wheel.
This problem becomes very noticeable when climbing steep heels because the front wheel could have a tendency to come off the ground.
To avoid this issue, bicycles designed to be better climbers (e.g., cross country hardtails) have longer chainstays and usually longer stems too.
The longer stem positions the handlebars further away and allows the rider to place more of their bodyweight on the front wheel.
Ultimately, short chainstays do not guarantee incredible performance if they don’t match the rest of the frame’s geometry and the style of riding that the bicycle is intended for.
2. Instability at Higher Speeds
A shorter wheelbase can cause instability at high speeds. To circumvent this issue, downhill mountain bikes often have longer chainstays than one may expect.
During downhill descents, the rider is often keeping a lot of their weight towards the rear wheel due to the nature of the terrain. If the chainstays are too short, the risk of looping out would be too high.
A longer wheelbase does not guarantee stability, however. The weight distribution is also very important.
A bicycle may have a long wheelbase thanks to a stretched front end but still be unstable due to short chainstays positioning the rider’s mass too close to the rear wheel.
3. Unpredictable Rear Wheel Behavior
A small rear-end facilitates snappy turns and tricks, but ultra-short chainstays are not always fun to ride as the bike becomes less predictable and makes it easier for the rear wheel to slide under you and throw you off the bike when you expect it the least.
Hence why even BMX riders stay away from ultra-short chainstay such as 12.5 inches.
4. Poor Tire Clearance
Short chainstays bring the rear wheel closer to the seat tube and limit the tires that a bicycle can use.
For example, you may be unable to replace a somewhat narrow slick tire with a wider threaded one even if both of them are designed for the same rim size.
To battle this issue, some bicycles have a curved seat tube which allows the frame to accommodate bigger tires despite the short chainstays.
5. Lack of Heel Clearance
If you install a rear rack and panniers on a bike with short chainstays, your heels may be hitting the bags when pedaling.
Whether this issue will manifest depends on the chainstay length, the rack architecture, the pannier design, and the anthropometry of the rider.
One of the ways to avoid this problem would be to purchase a rack that has mounts positioning the support legs further back. One option would Axiom’s Journey rack.
6. Inability to Fit Fenders and Racks
Excessively short chainstays could prevent the installation of a full rear fender covering the entire wheel simply because there isn’t space for it to fit.
By itself, a bicycle fender is pretty thin, but since it has to clear the tire, it ends up taking more real estate than one may envision.
Rear cargo racks could also be difficult to install on a bicycle with very short chainstays. Hence why bicycles designed to carry luggage have longer rear-ends.
7. Chainring Limitations
Ultra-short chainstays limit the size of the chainring that the bicycle frame can accommodate. This could negatively affect the gearing of the machine and one’s preferred style of riding.
What Are The Advantages of Longer Chainstays?
Longer chainstays come with the following advantages:
1. More Stability
Lengthy chainstays provide a longer wheelbase which results in greater stability when riding at high speeds.
Also, a longer bicycle is less susceptible to redirections caused by road irregularities and strong winds because the rear end isn’t as “jumpy”.
Another bonus is that the road feels less bumpy because the rider is closer to the center of the bicycle.
2. An Opportunity to Fit Biggers Tires, Racks and Fenders
Bicycles with longer chainstays provide enough room to install thicker tires as well as racks and fenders. If those accessories are important to your style of riding, a frame with a longer rear-end will be an appropriate choice.
What Are The Disadvantages of Long Chainstays?
1. Poor maneuverability
Bicycles with a longer wheelbase may be more stable, but the extra stability comes at a price – the agility of the bike suffers.
2. Less Jumpy
Moves like bunny hops are more difficult when the bicycle has a longer wheelbase. It’s still possible to learn tricks, though. I can do a bunny hop and a somewhat ok wheelie on my hardtail mountain bike which has a 430mm/17.5″ chainstay length.
3. Heavier Frame
Longer chainstays are heavier for three reasons:
- Longer tubing and subsequently more material;
- Longer chainstays = longer seat stays;
- Longer chainstays = longer chain = more weight;
However, the extra weight does not amount to much unless you’re obsessed with building the lightest possible bicycle and trying to drop grams.
4. Harder To Maneuver Over Obstacles
Longer chainstays make it harder to lift the front wheel. On one hand, that’s a positive characteristic because it reduces the chances of “looping out”, but there’s a real downside too – climbing technical off-road terrain becomes more challenging because it’s more difficult to unweight the front wheel when getting over obstacles.
5. Less Street Credibility
While this isn’t a technical downside, it’s still worth mentioning that in some circles bicycles with long wheelbases aren’t fashionable due to their “calmer” nature.
Of course, one shouldn’t be overly concerned with external opinions when choosing a bicycle. The goal is to select a machine that will serve you and your style of riding.
Far too many people buy needlessly sporty bikes just to look cool.
Chainstay Length and The Rider’s Height
The rider’s height affects the chainstay length too because the body acts as a lever. Chainstays that are considered somewhat long may be acceptable if the rider is on the taller side.
Conversely, some compact frames with short chainstays may be just fine for a shorter individual but too short for a taller person.
Having saith that, there are very tall men (e.g., 6’3″/190.5cm) who still prefer to ride with ultra-short chainstays.
Do Bicycles With Shorter Chainstays Accelerate Faster?
Shorter chainstays are considered stiffer because the tubing is shorter and less elastic. This trait is beneficial for power transfer and acceleration. Hence why it’s believed that short chainstays result in more efficient power output and acceleration.
However, not everybody agrees with this notion. Some say that the gains are mostly in people’s heads and the result of perception rather than measurable results.
At the end of the day, the acceleration prowess of a bicycle depends on its entire architecture…not just the chainstay length.
A lighter bicycle with a more aero position and faster tires could outperform one with “fashionably” shortened chainstays.
Sliding Dropouts = Adjustable Chainstay Length
Some frames have sliding dropouts allowing the rider to shorten or lengthen the effective chainstay length of the bicycle. The difference between the two available positions is usually around 1-2cm.
Ultimately, however, the main purpose of this feature is to tension the chain more easily while also having the ability to improve tire and chainring clearance upon demand rather than to turn a bike into a dirt jump machine.
Chainstay Length Should Not Be Analyzed In Isolation
Chainstays should not be analyzed in isolation as they’re only one of the variables in the system.
For example, shortening the chainstays makes it easier to lift the front wheel, but a higher bottom bracket and taller handlebars help with that too.
Chainstay Length According to Bike Type
The table below classifies chainstay length according to the style of riding:
|Bike Type||Chainstay in Inches||Chainstay in Millimetres|
|Enduro||about 17″||about 435|
Note: The chainstay length of some models may be outside of the ranges presented above due to custom geometries and different wheel sizes. But in most cases, the chainstay length of modern bicycles falls within those guidelines.
Don’t Obsess Over Chainstay Length
While chainstay talk could be fascinating, what matters more is the overall quality of the bicycle that you’re riding and your training programming.
Even if you buy the most technologically advanced bicycle in the universe with the most optimized chainstay length, it won’t replace deliberate practice.
A man who devotes a lot of hours to improving his skills and endurance would always report better performance than someone who spends more time obsessing over chainstay length than riding.
Keep in mind that the bicycle industry is often pushing different ideas as revolutionary because they are lucrative rather than truly necessary.
More often than not, non-professional cyclists don’t notice the effect of cutting edge tweaks that are supposed to revolutionize one’s cycling experience.