When I got my new mountain bike two years ago, I did my first wheelie. The problem was, I never intended to do a wheelie. I was in the middle of grinding up a steep singletrack and was suddenly riding with the handlebars in the air. I’m not a trick rider or a daredevil, so what happened?
Basically, my new bike had a short chain stay that I hadn’t gotten used to yet.
So, what is a chain stay on a bike?
The bike chain stay is part of the bike frame. It links the bottom bracket (pedal bearings) to the rear wheel center axis. (called the dropout) A shorter chainstay is often considered more “nimble” while a longer chain stay adds stability. A chain stay, protector is often applied to reduce chain damage from slapping.
Damage to the chain stay can range from scrapes and dings that make the paint job look worn out to full-on gouges and deep scratches. But, beyond the aesthetics of the chain stay, what do you need to know about the function of chain stay length?
Bike manufacturing has been trending toward shorter chain stays for several reasons:
- Shorter wheelbase
- Better rear traction
- Lighter and stiffer. This usually translates into more power from your pedaling!
- Better for tricks
The downfall of this industry movement toward shorter chain stays is that it leads to imbalanced geometry. With the rider positioned disproportionately over the rear wheel, it can cause erratic rear wheel behavior and instability at higher speeds. Plus, it can make it difficult to fit fenders, racks and rear saddlebags and may not provide adequate space for foot/pedal clearance.
DIY MTB Tip: Lubrication at the pivot points around the chain stay on your full suspension MTB is critical. Read more about this and other spots to maintain in – Grease and Lubrications for Your Mountain Bike
Obviously, the issue of long or short chain stay is much more complex than most of us ever even think about and warrants a little consideration if you’re looking to purchase a new bike or find ways to improve problems that could be caused by chain stay length.
How to Measure a Chainstay Length
The definition of the frame member provides the clues to measuring a chain stay length. From the center of the bottom bracket to the center of the rear wheel axle at the dropout. This is best described with a picture. Remember the common measurement unit is in millimeters. So the below is 17.35 inches times 25.4 = 440mm
How Does a Chain Stay Length Affect the Bike Handling?
The length of the chain stay rarely comes into play except in trials riding. Or, more accurately, it is affecting the riding of the bike immensely but in a way that few non-trick riders notice. Most casual riders, and even advanced riders, pay more attention to how a bike shifts or brakes than the less-obvious affects of chain stay length on their riding.
While longer chain stays provide more stability, shorter chain stays are more nimble. These attributes had different value for different individuals and different kinds of riding. For example, aggressive city commuters, who weave in and out of traffic and parked cars with little advance planning, probably prefer a shorter chain stay.
Meanwhile, city riders who stay in the bike lane and prefer to follow traffic laws and match surrounding traffic without much weaving, may prefer the stability of a longer chain stay.
For trick riding and technical mountain biking, having a shorter chain stay moves the rear wheel farther forward, it makes it easier to lift the front end of the bike off the ground. This makes it good for bunny-hops and balancing on the rear wheel or other moves that require great precision with the rear wheel.
Some trials riders may prefer a longer chain stay because it offers more leverage and allows them to put more power into moves like pedal kicks. Longer chain stays can offer more riding stability but less maneuverability.
Other Considerations for Chain Stay Length
There are several other situations in bike use in which chain stay length can come into play, beyond affecting bicycle handling.
- Longer chain stays may prove harder to fit in certain bike racks.
- If you’re carrying a lot of weight over the rear wheel (think: commuter biking with tools or bicycle touring with saddle bags), longer chain stays are better. The greater length allows for more space at the rear of the bike to pack and load your supplies. Also, it distributes the weight over a greater area, reducing the risk of cracking your frame.
- Pulling a trailer? You’ll probably want a shorter chain stay. The reduced maneuverability of the trailer arm will only be intensified by a longer chain stay.
- How do you lock your bike? Whatever your preferred locking style, the chain stay length may impact whether or not you can fit a U-lock or a heavy chain through the rear triangle. You may need to buy a longer cable lock, change your usual locking style or buy a different kind of lock to accommodate a longer or shorter chain stay.
What Is Considered a Long or Short Chain Stay?
To determine the length, chain stays are measured from the center of the bottom bracket to the middle of the rear axle. However, the standard length – and therefore classifying “long” or “short” – depends on the type of bike. Road bikes, mountain bikes, touring bikes and trials bikes all have a different standard range for chain stay length.
How Do Chain Stay Lengths Vary by Bike?
For mountain bikes, the typical length for a chain stay is 430 millimeters to 446 millimeters (with 430mm-450mm for 29ers and 425mm-435mm on 27.5in bikes). Meanwhile, road bike chain stays range from 405 millimeters to 435 millimeters. In trials bike geometry, the length of a chain stay ranges from 350 millimeters to 395 millimeters.
Anything close to – or shorter than – 350 millimeters is considered short, while longer chain stays are 390 millimeters or longer.
|Bike Type||Length||Source Link|
|BMX Bike||325mm to 355mm||Link|
|Trials Bike||350mm to 395mm||Link|
|Road Bike||405mm to 435mm||Link|
|Mountain Bike||430mm to 446mm||Link|
|Touring/Cruiser||420mm to 435mm||Link|
|Gravel Bike||425mm to 430mm||Link|
Are Chain Stay Protectors Necessary?
As the part of the frame that’s closest to the chain, the chain stay is often damaged or discolored by the chain. To combat this, most riders opt for chain stay protectors. Chain stay protectors can be as simple as a clear sticker that protects the paint job without actually obscuring it, or a sleeve or envelope that wraps around the chain stay.
DIY MTB Tip: A package of protective tape is pretty cheap. Applied to the high wear areas, they can keep your bike looking good and add some style. I love the All Mountain Style brand sold on Amazon link -> AMS High Impact Chain Guard
While different riders will opt for different types of chain stay protectors according to riding and stylistic preferences, pretty much everyone will advocate for using a chain stay protector. Some may say that a properly-tensioned chain should be enough to keep the chain from hitting the chain stay.
However, while that’s true in theory, it’s not often true in practical mechanics. Considering the easy protection chain stay protectors offer and their light weight and low cost, they’re definitely worth having.
F A Q
What is a Chain Guide?
A chain guide is typically a metal plate used instead of the largest chain ring on the rear hub. It helps keep the chain lined up for cleaner shifting and often reduces chain slap. When used in conjunction with a chain guard, it can also help protects the chain and rings from damage by rocks and other objects.
What is an Aggressive Bike Geometry?
Aggressive bike geometry typically puts your upper body lower than your hips (or at least, as low as possible) for better aerodynamics. With relaxed geometry, a biker’s torso is more upright. There are many drawbacks to aggressive geometry – and lower torso – such as twitchy handling and rider discomfort, so it’s generally not recommended except for competitive riders.
What is a Chainstay Angle?
According to BikeCad, chain stay angle “the angle from the rear axle to the center of the bottom bracket.” While it’s common to discuss and adjust the angle of many bike components, particularly head and top tube, chain stay angle is not very often addressed.
Partially, this is because there’s virtually no way to address chain stay angle once a bike frame leaves the manufacturing plant. Still, like many aspects of frame geometry, it can be helpful to understand it so that you can modify your riding appropriately. For good, broadly informative articles to understand bicycle geometry, check out “The ultimate guide to bike geometry and handling” or “Bicycle Geometry Explained!”
Looking for Some More Ways to Help Your Bike Last
Professional writer Kat Jahnigen was 2 miles from the nearest village – and roughly 2,310 miles – from the nearest English-speaking town – when her bike tire burst. At that time, she was a college student on a bike trip across the desolate, rocky island of Crete. It suddenly occurred to her that it would’ve been good to learn some basic bike repairs before setting off on a solo bike trip.
Check out Kat’s website WriteHire at writehire.net.