BMX bike riding relies on a harmonious fit between the bike and the rider. Road and mountain bikes are sized according to their seat tube measurement, since those riding styles often require the rider to spend long periods of time in the saddle. The sprinting nature of BMX racing, combined with the multiple jumps, means that this specific discipline of cycling often has its riders pedaling while out of the saddle. Due to this inherent trait of BMX racing, the bikes used for the discipline are sized based on the measurement of the frame's top tube.
Measure your height. Have a friend assist you with this step if you do not already know your height.
Measure the BMX bike. You will want to measure the length of the tube extending from the center of the head tube to the center of the seat tube since this measurement is a center-to-center measurement.
Choose a bike with a top tube length that is proportional to your height. If you are between 4 feet and 4-foot-4, you should choose a bike with a 15- to 16.5-inch top tube, while those with a height between 4-foot-2 and 4-foot-10 should select a bike with a 16- to 17.5-inch top tube. If you are between 4-foot-6 and 5-foot-1, you need a bike with a top tube between 17 and 18.5 inches long. Choose a bike with a 18.5- to 19.5-inch top tube if you are between 5 feet and 5-foot-4. If you are between 5-foot-2 and 5-foot-6, you should choose a bike with a 19.25- to 20-inch top tube, while those whose height is between 5-foot-3 and 5-foot-8 should select a bike with a 20- to 20.5-inch top tube. Select a bike with a 20.75- to 21.25-inch top tube if you are between 5-foot-7 and 6 feet tall, while those taller than 6 feet tall should choose a bike with a top tube of 20.75 inches or longer.
Tips & Warnings
- Remember that these are just guidelines, and that your torso and arm length may differ from others of your height.
- Give the bike a test ride before you buy it, if possible. Make sure that you are able to turn the bars without fully extending your outside arm. Conversely, you should make sure that your arms are not too cramped, making you feel uncomfortable on the bike.
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