Leg length shim - SRX gravel for Shimano RX910 (kit)

Leg length shims are used to increase the effective leg length on a shorter leg in cases where a cyclist suffers from a leg length discrepancy. Signs of a discrepancy can be:

• overreaching on one side at the bottom of the pedal stroke
• pelvis tilted or rider leaning to one side of the saddle in order to retain connection with the pedals through the bottom of the stroke
• one leg feeling under-extended whilst the other feels just right

Assuming the rider's position is correct, and their legs have been assessed to have a discrepancy, the issues above could be solved with the use of leg length shims. Shimming, with the correct amount of rise, can create a more equal leg extension, stabilise the pelvis and lead to a smoother and more controlled pedal stroke on the shorter side.

In some cases shims can be used to solve a functional leg length difference. This is when a rider has no physical difference in leg length, but shows a marked difference in leg extension when riding. In cases like these it’s always advisable to see a bikefitter first, prior to making assumptions about what is required.