Mountain Bike Size Guide
How to Size your Mountain Bike
To determine your ideal mountain bike size all you need to know are your height and inside leg measurement. We have prepared an easy to follow guide to ensure that you choose the right size mountain bike.
How Mountain Bikes (MTB) are measured
Mountain bikes are measured by the distance between the centre of the bottom bracket and the top of the seat tube. Generally the unit is in inches and adult sizes usually range from 14” – 24”. The length of the top tube will vary depending on the seat tube length, and will get longer as the frame size gets bigger to accommodate a taller rider.
For gravity bikes such as downhill bikes, dirt jump bikes, BMXs and 4x bikes, sizing is not as critical as bikes are designed to be smaller in proportion to the rider, therefore they are usually described as short, medium or long. If in doubt call our helpline on 01792 799508.
All the other angles and lengths on a bike are usually the same, as they are normally determined by the handling characteristics of the bike and its geometry – so you just need to focus on three measurements when sizing a bike:
- Seat tube length/frame size
- Top tube length
- Standover height
What to Measure
Manufacturer’s recommendations are based on your height, so if you are 5”10, you are going to be best suited to riding an 18” bike. This is however based on the assumption that your inside leg is 31”-33”. If you are outside of that range (and it’s not unusual if you are) you might have to adjust the size of the bike accordingly.
It is easy to find your height with a tape measure and a helper – it can be done on your own but an assistant makes it easier. Without shoes, stand against a wall wearing and place a book on your head, then simply measure the distance from the bottom of the book to the floor.
Quick Reference Guide
MTB – Off Road (Hardtail)
MTB – Off Road (Full Suspension)
|Height||Inside Leg||Frame Size||Size||Height||Inside Leg||Frame Size||Size|
|4’10″ – 5’0″||26″ – 28″||13″||5’4″ – 5’7″||28″ – 30″||14″, 15″||X Small|
|5’0″ – 5’3″||27″ – 29″||14″, 15″||X Small||5’8″ – 5’9″||29″ – 31″||16″, 17″, 18″||Small-Med|
|5’4″ – 5’7″||28″ – 30″||16″, 17″||Small||5’10″ +||30″ – 32″||19″, 20″, 21″||Large|
|5’8″ – 5’9″||29″ – 31″||18″, 19″||Medium|
|5’10″ – 5’11″||30″ – 32″||20″||Large|
|6’0″ – 6’2″||32″ – 34″||21″|
|6’2″ – 6’4″||33″ – 35″||22″||X Large|
Stand over is the length of your inside leg minus the top tube height i.e. the difference between ‘you’ and the top tube of the bike. The stand over height of a bike can usually be found in the geometry section on our product pages or the manufacturer’s website – if you can’t find it, please call us and we’ll be able to give you an answer.
- Female specific bikes don’t just come in different colour schemes with flowers and patterns – women generally have longer legs and shorter bodies than men, so female specific bikes have a shorter top tube to suit the female form better.
- If you find you have bought a bike and it’s slightly the wrong size, or if you feel you are in between sizes, there are still things you can do to fix it. Moving the saddle on its rails can help, as does a longer/shorter stem and handle bar position. It’s possible to get a bike to fit you perfectly, whatever shape you are, so don’t lose hope just yet.
- Sizes do vary between manufacturers so just because your old bike is one size, doesn’t automatically mean your new one will be too.
- Mountain bike sizes are completely different to road bike sizes, so please don’t cross reference the two.