Size Guide

Picking the right mountain bike frame size is critical for an enjoyable riding experience. With a few simple bits of information, it's easy enough to know what size frame is right for you.

Mountain bikes are measured in the distance from the center of the crank to the top of the seat tube frame. That is the generally accepted way of measuring, but be careful: a few manufacturers measure from the intersection of the top tube and seat post to the crank axle instead, which gives a slightly different number. Also, some manufacturers just go with generic small, medium and large designations, so it's important in those cases to get the exact inch length before buying.

To choose the right mountain bike frame size, the two important facts to know are your height and your inseam measurements. The inseam measurement is the most critical, and it's best if you are barefoot at the time. If you don't know the number offhand, there are a number of ways to measure it yourself. Among them: stand up against a wall with a book between your legs, pressed up against your pelvic bone, and mark on the wall where the top of the book is. That's your inseam.

Someone between 4'11"-5'3", with a 25-27-inch inseam, is generally recommended for a bike frame size of between 13-15 inches. Someone 5-3 to 5-7 with a 27-29 inch inseam would be more comfortable in a 15-17 inch mountain bike frame. If you are 5-7 to 5-11, with a 29-31 inch inseam, a 17-19 inch mountain bike frame is best.

Taller riders naturally need a bigger frame. Someone who is 5'11" to 6'2" with a 31-33 inch inseam would get a 19 to 21 inch mountain bike frame. At 6-2 to 6-4, with a 33-35 inch inseam, 21-23 inch bike frames work, and someone taller than 6-4 with an inseam 35 inches or greater needs something a bit larger, generally more than 23 inches.

That works for most riders, but there are some exceptions. If you are a rider who is more aggressive going down the mountain and need something more maneuverable, a frame that's a size smaller may meet your needs more. Also, bikes made for women are sized slightly differently, so be sure and double-check to make sure the fit is the appropriate one.