Mountain bike size guide: 8 Key points to choose the best size for you

Finally end the guesswork! In this step-by-step guide you'll find everything you need to know to make your final choice.

mountain bike size guide

When trying to choose a mountain bike size, size charts put you on the right pedal to go through the hilly ride that is an optimal bike fit. 

There are important things to look for that a mountain bike size chart will not tell us, jump in and let’s look at them!

As a long-time bike rider, it is impressive how often I see my fellow riders having trouble with their bike size.

Bike size is the pillar for a good bike fit, if you get this one wrong it will not matter how much you tweak your bike, your level of comfort, safety, and performance will always be lacking.

Our mountain bike size guide will serve as the roadmap to a more safe and pleasant experience.

Table of Contents

Mountain bike size guide first steps and quick tips

In many aspects of life, size does matter. This statement can be applied with regards to a mountain bike.

The most important measure that will follow you throughout your cycling life will be your inseam length. Height is also important but is used mostly as a reference standard measure, inseam will give you a personalized idea because more often than not people with the same height have different inseam measures. 

Measuring the inseam length is an easy process, here is how:

  1. Stand against a wall shoes off with your feet slightly away from one another
  2. Place a hardcover book between the your legs. The spine of the book under your crotch.
  3. Imagine that the book is the bike seat, so the book should firmly touch the crotch.
  4. Make sure the book is leveled with the wall and measure from the spine of the book to the ground.

Done, this is your inseam length!

While you are at it you can re-check your height if some time has passed since you did it, just measure from the ground to the top of your head.

Now place yourself into the mountain bike size chart:

HeightInseam LenghtFrame SizeBike Size
4’11” – 5’3″
147cm – 160cm
25″ – 27″
63cm – 68cm
13″ – 15″
33cm – 38cm
5’3″ – 5’7″
160cm – 170cm
27″ – 29″
68cm – 74cm
15″ – 17″
38cm – 43cm
5’7″ – 5’11”
170cm – 180cm
29″- 31″
74cm – 79cm
17″ – 19″
43cm – 48cm
5’11” – 6’2″
180cm – 188cm
31″ – 33″
79cm – 84cm
19″ – 21″
48cm – 53cm
6’2″ – 6’4″
188cm – 193cm
33″ – 35″
84cm – 89cm
21″ – 23″
53cm – 58cm
6’4″ and up
193 and up
35″ and up
89cm and up
23″ and up
58cm and up

Quick tips:

  • If you find yourself between sizes, choose the small one you can make up for the difference by tweaking or changing your seat height, crank arms, stems, and handlebars.
  • If you are unable to have the correct saddle height, and your reach to the pedals is too short or too long your bike size is not right.
  • You will know that a bike size is ok when the top tube leaves enough space for two fingers to fit below your groin.
  • Always check the manufacturer’s size chart as they may vary from brand to brand

How are mountain bikes measured?

  • Reach
  • Stack
  • Head tube angle
  • Chainstay length
  • Bottom bracket height
  • Wheelbase

Mountain bike reach

Reach is at the top of the list by no casualty, it is the most important factor as it will directly impact the posture you’ll have when riding your mountain bike.

A reach that is too short will make you have an upright position and will limit your range of motion. If it’s too long you’ll tend to lean forward, causing overly stretched arms and shoulders.

Reach is measured horizontally from the center of the bottom bracket to the center of the head tube.

Mountain bike stack

Stack is the real deal to know the true handlebar height as it takes into account the bottom bracket height and fork length.

You should consider it if you find yourself in the small range of bike sizes. It will help you avoid the feeling of a tall handlebar height and go through long rides more comfortably.

If you find yourself in the medium and large range of sizes you should not worry too much about it. Only if you want to have a lower front when climbing or a more aerodynamic position.

Stack is measured vertically from the center of the bottom bracket to the center of the head tube and can be augmented using spacers or by changing your stem. 

Mountain bike head angle

Head angle contributes to the steering responsiveness of a bike and sometimes is taken too seriously but it should not as other factors like wheelbase, fork offset, wheel size, and others also contribute to the overall riding experience of the bike.

  • Slack angle bikes will give you extra control when going very fast or downhill. Normally they have an angle between 63° to 66°.
  • Steep-angle bikes are better for low-speed and uphill. Usually, they have angles between 69° to 71.

Mountain bike chainstay length

Chainstay length is more of a factor that contributes to the playfulness of the bike and its impact on bike fit is null.

Short chainstays (420-435mm) make it easier to do wheelies and manuals as your weight has more impact because of the proximity of the wheel to your body. But careful though, this can mean an accidental wheelie when riding uphill.

Long chainstays (440-455mm) will add to the balance of the bike when going uphill and at speed.

The chainstay is measured horizontally from the rear wheel axle to the center of the bottom bracket.

Mountain bike bottom bracket height

Bottom bracket height combined with head angle and wheelbase contributes to the maneuverability of the bike.

Short bottom brackets make the bike’s center of gravity closer to the ground, this greatly improves the balance of the bike. They are perfect for cornering and flat terrains.

Chainstay height is measured from the center of the crank spindle and to the ground.

Mountain bike wheelbase

Wheelbase Is the final piece of the puzzle that will impact the feel of your riding with the other measures mentioned before.

The simplest definition for long and short wheelbases is that:

  • Long wheelbases add balance so they are great for fast descents.
  • Short wheelbases are easier to maneuver at low-speed hard trails.

Now that you know all the important elements of an MTB you can choose the bike that will better adapt to your riding style and terrain preferences.

What are the differences between men and women mountain bikes?

If you are a woman who’s riding a mountain bike, the mountain bike sizes, as well as its corresponding factors, will be different than those of men, especially:

  • Handlebars
  • Bike sizes availability
  • Saddle
  • Crank arms

Handlebars on women’s mountain bikes tend to be narrower than men’s bikes. However, the use of broader handlebars on a mountain bike should not be ruled out. Wider handlebars are more stable. Be sure to give the wide handlebars a test run. You can tell if the handlebars are right for you if the inside edge of your hand is aligned with the outside edge of the crease of your armpit. Use a mirror to assist you.

Saddles of women’s bikes are shorter and wider than the saddles of men’s bikes. Women’s bike saddles have greater width since women’s sit bones are wider than men’s. 

Crank Arms are shorter in women’s mountain bikes as opposed to men’s bikes. Longer crank arms can lead to pain in the lower body for smaller riders.

Women’s mountain bike size chart

HeightInseam LenghtFrame SizeBike Size
4’10” – 5’2″
148cm – 158cm
25″ – 27″
63cm – 68.5cm
13″ – 14″
33cm – 36cm
5’2″ – 5’6″
160cm – 170cm
27″ – 29″
68.5cm – 74cm
15″ – 16″
38cm – 41cm
5’6″ – 5’10”
170cm – 178cm
29″ – 31″
74cm – 79cm
17″ – 18″
43cm – 46cm
5’10” – 6’1″
180cm – 185cm
31″ – 33″
79cm – 84cm
19″ – 20
46cm – 53cm

The finish line

Taking your measurements correctly is the key to choosing the right mountain bike size.

If you are buying your mountain bike online, always reach out to the seller and ask for their size chart if it’s not visible on their site and ask all the questions you need to ask and if you are buying in your local bike shop don’t hesitate to have a test ride. 

Mountain biking is a great sport for outdoor and adventure-loving people. All adventures have their risks so it is really important to always use all the safety equipment.