Mountain bike frame size: which mountain bike size?

When buying a new mountain bike, it is very important to pay attention to a suitable frame size. The correct frame size depends on your height. You can calculate the correct frame size for your new mountain bike in various ways. In this guide we tell you everything about the mountain bike frame size and you discover, among other things, a handy size chart.

Calculate mountain bike frame size

Let’s start with how you can calculate the right frame size for a mountain bike yourself. Contrary to what many think, you do not have to go to the bicycle shop especially for this. Of course you can, but you can also easily do it yourself. View the step-by-step plan below.

  1. Take off your shoes and place your feet about 6 inches apart (slightly apart)
  2. Measure the total distance from the ground to the crotch height (you can do this yourself with a tape measure)
  3. You can then multiply this measured length by 0.68: the number that comes out is the correct frame height. Isn’t there a whole number? Then round it up for sporty rides and down if you’re cycling especially slowly

In addition to the above calculation, you should also take the following into account. Do you have a mountain bike seatpost with suspension? Then you have to remove about 4.5 centimeters from the just calculated frame size!

Factors that play into the MTB frame size

Although you can easily calculate the correct frame size for your mountain bike with the step-by-step plan above, we would like to make a comment. There are a number of factors that play into a good frame size.

  • Seat tube length: the length of the seat tube*
  • Stack: vertical distance from bottom bracket to headset
  • Reach: horizontal distance from headset at bottom bracket level

* The seat tube length may vary per bike. Therefore, two 23 inch bicycle of different brands can differ a lot from each other. Yes, they are both 23 inch bikes, but they have different seat tube lengths.

mountain bike frame size
The reach and stack are important factors for the correct frame size. © MTBdex.com

Cycling Style Affects Best Frame Size

The correct stack and reach dimensions depend on your cycling style. If you have your handlebars low (a low stack), you can cycle faster, because you sit more aerodynamically on your bike. A higher handlebar (a high stack size) means you sit more upright and you can cycle more comfortably (more useful for technical MTB routes).

As for the reach of your MTB, it also depends on your riding style. A longer reach is suitable for a more aggressive driving style. A short reach is – just like with a high stack size – a lot more comfortable cycling.

Mountain bike size chart

Many mountain bike outlets use different names for frame sizes. Some talk about sizes like XS, S or L, while another webshop talks about frame heights like 35 to 40 centimetres. To offer you some overview, below is a commonly used MTB size chart.

Frame size in cmFrame size in inchesFrame size in letters
35 – 41 cm14 – 16 inchXS
41 – 44 cm16 – 17 inchXS / S
44 – 48 cm18 – 19 inchS / M
48 – 51 cm19 – 20 inchM
51 – 52 cm20 – 21 inchM
52 – 54 cm21 – 22 inchM / L
54 – 56 cm22 – 23 inchL
56 – 61 cm23 – 24 inchL / XL

Mountain bike frame size FAQ

How can I calculate the best frame height for a mountain bike?

You can do this by using the inner length measurement technique. Stand with your feet 6 inches apart, then measure the distance from the floor to crotch height. Multiply this by 0.68 to calculate the correct frame size in centimeters.

What else should I look for for the right MTB frame size?

In addition to the frame height, it is also important to look at the stack (vertical distance from the bottom bracket to the headset) and the reach (horizontal distance from the headset to the bottom bracket) of a mountain bike.

Can bicycles of the same inch differ from each other?

That is certainly possible: this is because each bicycle brand has developed its own ergonomics for a mountain bike. The seat tube height can be the same, while the frame can be higher or lower. Therefore, look further than just the number of inches!

Is a mountain bike frame size for women different?

For ladies there is often a special ladies range. With a women’s mountain bike, the reach is often shorter, because in many cases women have a shorter back length than men. So it is interesting for women to look at special women’s mountain bikes for the best frame size.

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