Choosing the right size for your bike is vital to be able to enjoy it to the fullest without having to worry about possible future postural problems, but how do we know what size bike we need? Although the issue is important, you will now see that it is easy to solve.

The key to choose the size of bike will be the height of our hip or inseam measurement. To take the measurement we must place ourselves with our back against the wall and our feet straight and slightly apart, place a book or a ruler between our thighs touching the crotch and measure the distance from the ground to the highest and farthest part of our body from the chosen object.

Once this measurement is taken, multiply it by 0.54 to know our perfect mountain bike size in centimeters, or by 0.21 for inches. Most mountain bike manufacturers opt for the second option.

Stick to the wall with your back and heels straight. Hold a book between your legs and measure the distance from the book (from the top) to the ground.

Multiply that measurement by 0.54 to get your size in cm, or by 0.21 to get your bike size in inches.

Example to calculate your bike size

For example, if our hip height or inseam measurement is 80, multiplied by 0.54 would equal 43.2, so our perfect size would be 43. In case the manufacturer of the bike we want measures the bike size in inches we would multiply 80 by 0.21, which would give us a result of 16.8. Our bike size in this case would be 17.

The above formula is valid for choosing the MTB size, i.e. a mountain bike. In case we want to buy a road bike, we should multiply the hip height or inseam measurement by 0.65. That is, taking the same example of the previous paragraph, we would multiply 80 by 0.65 to know that our ideal bike size for road bikes is 52.

Now that you know how to measure the distance from the hip, here are some tables to help you know what size bike you need for both MTB and road.

MOUNTAIN BIKE size according to height or inseam of the cyclist


148-158 cm 70-74 cm 13″-14″ XS

158-168 cm 74-75 cm 15″-16″ S

168-178 cm 75-81 cm 17″-18″ M

178-185 cm 81-86 cm 19″-20″ L

185-193 cm 86-90 cm 21″-22″ XL

ROAD OR ROUTE bike size according to rider’s height or inseam height


155-160 cm 68-74 cm 47-48 cm XSS

160-165 cm 71-76 cm 49-50 cm XS

165-170 cm 73-79 cm 51-52 cm S

170-175 cm 76-81 cm 53-54 cm M

175-180 cm 78-84 cm 55-56 cm L

180-187 cm 81-86 cm 57-58 cm XL

187-190 cm 83-88 cm 59-60 cm XXL

190-196 cm 86-92 cm 61-62 cm XXL

We can not always choose the size of our bike, either because we are going to buy it second hand, because we have been given it, inherited, etc ….

In these cases we still have some alternatives to adjust the bike’s measurements to our size. For example, we can play with the setback of the seat post, the placement of the saddle, the size of the stem or the number of steering spacers. If this is your case you can take a look at this other article where we explain it.

So, one way or another, we will be able to have a custom frame and a perfect MTB size. The bike size will be the right one to avoid physical problems and to perform to the maximum in each of our outings.