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Are Mountain Bike Stems Universal

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Once you find the bike stem that puts the handlebars just where you want them, you want to use it for your future bikes too.  Is it possible, and are they universal and you could just bring it right over?

Yes, mountain bike stems are almost entirely universal.  31.8mm is the most common size with a few 35mm sizes coming in lately.  So mountain bike stems are about as universal as it gets.

What is a Mountain Bike Stem?

A bike stem is a metal knuckle that attaches the fork steering rod with the handlebars.

They come in different lengths and different rising heights, but they are typically universal at 31.8mm for the handlebar clamp size and 40mm for the length.

Is there a Universal Handlebar Clamp Size?

bike stem showing the handlebar clamp size

The Handlebar clamp size of a bike stem is the width of the part that wrap around the handlebar and bolts tight.

The handlebar clamp size of the bike stem needs to match the handlebar.  Luckily, a standard handlebar width of 31.8mm has been in use for years.

So, nearly all mountain bike stems sold today have a clamp size of 31.8mm or 31.7mm.  That is the same width of 1-1/4″, it’s just the math the company uses to convert it to metric.

What it means is that bike stems have a universal bike stem clamp width.

Is There a Universal Bike Stem Length?

Bike stem length is the distance from the bar that comes up from the fork steering to how far forward where it wraps around the handlebars.  In short, it’s how far forward of the fork the handlebars sit.

Ideally you want the handlebars on your mountain bike to be a length so that when you sit on the seat, you can reach the handlebars comfortably with arms a little bent.

There are many different lengths of bike stems you can get and they range from 100 to 140mm generally.

However, regardless of the bike stem length, the bike stem itself is still universal since it’s the way it connects that determines how universal it is.

So are Mountain Bike Stems Universal?

Yes, bike stems are universal.  Where they connect to the handlebars is almost always the same width.  Where it connects to the fork steering rod is the same width.

So there is around a 95% chance that a bike stem will fit your bike.

The only difference is that a few newer handlebars on trail bikes have a 35mm thickness so that requires a 35mm bike stem.  However, there are few like this and you’d really have to look for them.

If you pick up a cross country bike, you’re going to have a standard bike stem on it.

What is the Common Sizes?

31.8mm is the most common bike stem clamp size, with 35mm coming behind just lately.

For stem length, 40mm is the most common length.  The length of the stem determines how far forward of the fork steerer the handlebars are.

For the average person 40mm is fine but it’s possible to get different lengths to set the handlebars more forward for a more comfortable position.


So in conclusion, mountain bike stems are universal.  If you pick up a xc bike or a trail bike, you’re going to have a universal bike stem on it so if you pick up a standard 31.8mm bike stem to put on your bike, it’s going to work.


About the Author

Tony K

Senior Technical Writer,

Tony K is a technical editor at He has a focus on downhill bike riding but still loves xc bikes too.

With more than ten years of mountain biking experience and more than 5 years testing mountain bikes, Tony has ridden and tested hundreds of different bikes and products, everything from XC to enduro bikes. Tony regularly competes in mountain bike races while seeing how long those compontents can hold up which gives me a lot of insight.

When he isn't shredding down a mountain or camping out, he is writing reviews for Mountain Bike Experience.

Rides: Surly Lowside, Canyon Exceed