Selecting the proper mountain bike size is not an exact science. The determining factor in choosing the right bike should always be its comfort level when you sit on it and ride. In other words, this is an individualized selection process…you can’t really know which bike size is right for you until you actually get on it and ride. With that being said, there are a few basic guidelines to follow in facilitating your mountain bike purchase.
The frame size sets the tone for overall mountain bike comfort; all other appropriate dimensions of the bike can be achieved with the proper frame size. To determine which frame is the right size for you, you need to know your height and your in-seam measurement. Your height will essentially guide your sizing process. Mountain bike manufacturers list frame sizes according to seat tube length, and seat tube lengths are directly linked to your height. The following is a basic guideline (in size and inches) for frame size, as manufacturers would list them, and correlating rider size:
- XS (13-14 inches): for riders between 5 ft. and 5 ft. 4 inches
- S (14-16 inches): for riders between 5 ft. 4 inches and 5 ft. 7 inches
- M (16-18 inches): for riders between 5 ft. 7 inches and 5 ft. 10 inches
- L (18-20 inches): for riders between 5ft. 10 inches and 6 ft. 1 inch
- XL (20-22 inches): for riders over 6 ft. 1 inch
The in-seam will measure your stand over height (the clearance between your crotch and the top tube of the bike when straddling the bike frame). Experts recommend at least a 1.5″ stand over height. So for example, if your in-seam is 28 inches, the bike frame should stand no higher than 26.5 inches off of the ground.
Once the frame height is established, things like seat height/position and handlebar reach/height can be addressed. Just as with frame sizing, however, this process in mountain bike sizing is best judged by your overall comfort level. There are general guidelines to follow, though:
– Seat Height and Position: When sitting on the bike, your knee should be slightly bent at the downward most position of the pedal (i.e. your legs should never be completely extended at any point in the pedaling process when seated). Start with the seat as level as possible and adjust to a slightly tipped back or slightly tipped forward position as dictated by your comfort.
– Handlebar Reach and Height: In terms of mountain bike sizing, handlebar adjustments are the most subjective aspect. Again, let comfort be your guide. Generally speaking though, your elbows should be slightly bent and the handlebars should be set higher than the seat (this is particularly the case for beginners).
Follow these basic guidelines for mountain bike sizing and get riding! Just remember, be comfortable and be safe!