What mountain bike frame size do I need?

What mountain bike frame size do I need?

Once you have found your dream mountain bike, there is still one pressing question: Which mountain bike frame size do you need? Choosing the right frame size ultimately determines how much fun you will have with your new MTB. That’s why you should take some time when determining the correct frame size.
Measure the correct mountain bike frame height
This question inevitably pops up before you buy a new mountain bike. And this question should not be underestimated. Because only with the right frame size you will use the full potential of your new MTB. The fact that each person has very individual body proportions (so, for example, the ratio of leg length to height), makes the matter complex. In addition, not all manufacturers specify the frame size uniformly with the unisex sizes S, M, L or XL known from the fashion industry. In this article, we explain how to measure your inner leg length and how you can use this measurement to find the right bike size for you. With a table we present the different sizes in inches or centimeters. So you can find the right frame size in no time. We also briefly discuss wheel size and explain which measurements you should keep in mind.
Measure the inside leg length to find the correct frame size.
To find the right frame size for your mountain bike, you need to measure your inside leg length. Don’t worry, it takes less than two minutes.

How to determine the correct frame height: Measure inseam length (aka inside leg length)

Inside leg, or inseam length, is the key body measurement when looking for the right MTB frame height. To determine it, you need nothing more than a measure, a level and two minutes of your time. If you don´t feel like measuring your leg length, you can also roughly calculate it by using a statistical value and your height. For this, men simply have to multiply their own height in centimeters by 0,483. Women have statistically longer legs, so they need to multiply their height by 0.503 to determine their theoretical leg length (see table below). When buying an expensive mountain bike, however, you should still take a moment to determine your leg length individually. Because the mathematical method with its average values can of course differ.

Here’s how you measure the inside leg length in less than two minutes.

Determine the inside leg length with a level and measure tape.
To determine the length of the inner leg, you only need a measure tape and a level. If necessary, you can also use a book.
The inside leg length is measured barefoot and with your back against a wall.
To correctly measure the inside leg length, be sure to remove your shoes and stand with your back against a wall. Then place the level between your legs. (Step 2)
To measure the inner leg length, all you need is a measure and a level. 1. Take off your shoes and stand barefoot or with socks with your back against a wall. It is very important to do this without shoes. 2. Take the level horizontally and yes, press it onto your crotch from below until you feel a slight pressure in that area. Check the level is indeed 100% level before proceeding to step 3. If you don’t have a level, you can also take a book (preferably a large hardcover book up to four inches thick). To ensure that the spine of the book is parallel to the floor, it is important that one side of the book is completely against the wall behind you.3. now measure the distance between the floor and the top edge of the spirit level (or book spine) held horizontally.THAT’S IT: SIMPLY READ OFF YOUR PERSONAL INSEAM LENGTH.
Determine the inseam length with a measure tape.
Check that the level is horizontal and then measure the distance to the ground with the measure tape. (Step 3)
Convert inseam length to frame size.
With a calculator you can convert your inseam length to the right frame size with a formula. Attention: the manufacturers do not specify the frame sizes uniformly. Some use inches, some centimeters, some use the unisex sizes from the fashion industry.

Calculating the mountain bike frame height

To calculate the correct bike frame size, simply type the inside leg length (in centimeters) determined above into the calculator. If you want the result in inches, multiply it by the number 0.226 to get the measurement for the perfect seat tube length. If you want the result in centimeters, just multiply the inseam length by the value 0.574. Typically, bike manufacturers offer their frame sizes in increments of two inches or three to six centimeters. In the table below, you can compare frames in centimeters to inch frame sizes and unisex sizes like S, M or L. Basically, it doesn’t matter how a manufacturer specifies their frame size, you just need to convert your leg length using the correct formula. The inches or centimeters of the frame size usually describe the length of the seat tube. If you do not trust the size specifications, you can also use the specified seat tube length from the geometry table of the mountain bike to find the correct frame size. The calculated ideal length of the seat tube must be rounded to the nearest frame size, which is offered by the corresponding MTB brand.

This frame size table gives you a rough overview of the mountain bike sizes.

155 -160 cm 61-67 cm XS 14-15″ 33-36 cm 26 – 27,5 Inch
160-165 cm 67-70 cm S 15-16″ 38-40 cm 26 – 27,5 Zoll
165-170 cm 70-75 cm S/M 16-17″ 40-43 cm 27,5 Inch
170-175 cm 75-79 cm M 17-18″ 43-46 cm 27,5 – 29 Inch
175-180 cm 78-83 cm M/L 19″ 46-49 cm 29 Inch
179-186 cm 81-86 cm L 20″ 49-52 cm 29 Inch
186-197 cm 87-92 cm L/XL 21″ 53-55 cm 29 Inch
198 cm and taller 93 cm and more XL 22″ and taller 56 cm and taller 29 Inch
Because each bike manufacturer indicates its frame sizes in a different way, we have created this frame size table for better orientation. In the table, we have the different frame size specifications in inches, centimeters and unisex sizes comparably represented. Also, the approximate matching body size and inner leg length is determined. We also give you a recommendation on the best wheel size for each size. NOTE: The above conversion factors for frame sizes in inches or centimeters and the table apply mainly to mountain bikes. Road bikes or trekking bikes require their own conversion formulas to find the correct frame height. Unlike mountain bikes, these bikes have much less saddle extension, which means the seat tube needs to be longer. 0

How does body size affect wheel size?

In general, you have to distinguish between wheel size and frame size for mountain bikes. The usual wheel size for adults is 26, 27.5 or 29 inches and varies depending on the area of use, but also the size of the rider. It is therefore possible that a very tall person may need a 23 inch bike frame, which in turn has a 29 inch wheel built into it. The two dimensions in a bicycle can quickly be confusing for beginners, which is where we come in to explain and simplify these things. For example, children bikes come in two-inch increments starting at the wheel size of 12 inches. The rule of thumb for the correct wheel size is simple. The bigger you are, the bigger the wheel should be. The table above also gives you an orientation. Should you have more questions about wheel sizes, we also have an extra article.


“Choosing the right MTB frame size seems complex at first. But if you take 15 minutes of your time, you can calculate your correct frame height very quickly and easily with the help of this article. Regardless of the frame size, the saddle and handlebars can be adjusted within a certain range to your body proportions or preferences.”
In this article, the author Ludwig Döhl has incorporated his experience from over 100,000 kilometers in the mountain bike saddle.

About the author


... has spent more than 100,000 kilometers in the saddle of over 1000 different mountain bikes. The essence of many hours on the trail: Mountain bikes are awesome when they match your personal preferences! With this realization, he founded bike-test.com to assist cyclists in finding their very own dream bike.

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