What Size Mountain Bike Do I Need?

Getting a bike that feels and rides well for your size and style of riding has several components to it, and when people ask, what size mountain bike do I need? They are not always asking the most obvious question, a better question would be what size mountain bike would fit me better?

Frame size and how it compares to you height is the first thing that you need to look at if you want a good fitting bike, and this is not always a stock standard measurement on all brands of bike.

In most brands of bike the frame height is the distance from the centre of the crank to the top of the frame at the seat tube, the height of the rider is best measured from your in-seam (inside leg) measurement rather than just you’re over all height.

Mountain Bike - Size Guide

Your Height| Your In-seam Length |Bike Frame Size

4'11" - 5'3"| 25” - 27” |13 - 15 inches

5'3" - 5'7" |27" - 29" |15 to 17 inches

5'7" - 5'11"| 29" - 31" | 17 to 19 inches

5'11" - 6'2"| 31" - 33" |19 to 21 inches

6'2" - 6'4" |33" - 35" |21 to 23 inches

6'4" and up| 35" and up| 23 inches and up

You can see from the chart above that your height may vary from 3 to 4 inches, but your in-seam may only vary by a maximum of 2 inches.

Your height may be exactly the same as another rider but your in-seam measurement can be different due to torso length, that is where proper setting, like your seat height, the top tube length, and handlebar adjustment comes into play, to make sure the bike feels and fits right.

Bike Comfort

If you are at a height or have a leg length that is somewhere in the middle of 2 bike frame sizes, trying several of them to see what feels more comfortable is the best option.

You can get away with a frame that maybe an inch or so under-size (helps minimize weight), as longs as the seat is set at the correct height, and all the other mountain bike parts are positioned correctly for your size and style of riding.

When your foot is on the pedal at the bottom of the rotation you should have only a slight bend in your knee on that side, if the seat is too high you will minimize the downward pedalling power, but also risk injury if you have to step off the bike in a hurry.

If your seat is too low, again this will affect your pedalling power, but also cause the knee joint to open too much at the top of the pedal rotation, which can lead to long term damage of the knee joint.

Handlebar Height

The height of the handlebars is very much a personal preference, and can be anywhere from level with the seat height or an inch or more below it.

The handlebar height determines the angle of your torso from your hip to your head, having the wrong angle can put unnecessary pressure on your lower back, or cause you to have to carry too much weight through your shoulders if your lean is too far forward.

If you are riding for long periods of time you need to be as comfortable as possible.

What Size Mountain Bike do I Need?

The simple answer is one that suits your in-seam measurement and height, but also one that can be adjusted for your comfort without affecting your riding power or style.

As long as the frame size of your bike is close to ideal, with slight adjustments in the other mountain bike parts that add comfort as well, it can be a perfect fit and the right size!