Bike & Gear guide

CRANK LENGTH

Crank length influences pedaling range, leverage, cadence, and clearance. Age alone is not enough to determine the right size; consider inseam, leg proportions, gearing, skill, and how the rider moves.

Use measurements as a starting point

Record inseam and current crank length. Note whether the rider rocks at the hips, struggles through the top of the stroke, or has difficulty accelerating smoothly.

Longer is not automatically faster

Extra length may add leverage but can increase joint range and reduce clearance. Shorter cranks may support cadence and clearance but also change the effective gearing feel.

Coordinate cranks with gearing

Changing crank length can change how a familiar gear feels. Evaluate crank and gearing changes together rather than treating them as unrelated upgrades.

Get qualified input

For a growing rider or a rider with discomfort, involve a coach, qualified fitter, or medical professional as appropriate. Do not diagnose pain from an online chart.

Official resources

USA BMX New Rider Information ↗

This guide is an educational starting point. Follow current USA BMX rules and manufacturer instructions, and ask a Reaper Racing coach or qualified bicycle mechanic when you are unsure.