What crank length do most bikes come with?

Most road bikes come with 170 mm or 172.5 mm cranks. This suits riders with inseam measurements of approximately 79-85 cm.

Does crank length really matter?

For most riders, the difference between 170 mm and 172.5 mm is negligible. However, very short or tall riders can benefit significantly from correct crank length, especially for comfort and injury prevention.

Should I go shorter or longer?

There is a trend towards shorter cranks, especially for time trials and triathlons, as they allow a more aerodynamic position. Shorter cranks also suit riders with hip flexibility issues.

BikeCalcs

Crank Length Calculator — Optimal Crank Arm Length

Find the optimal crank length based on your leg length.

Inseam Length

How We Calculate This

Crank Length Formula

Crank Length (mm) = Inseam (cm) x 2.16

The result is rounded to the nearest standard crank length: 165, 167.5, 170, 172.5, or 175 mm. Standard crank lengths come in 2.5 mm increments.

Frequently Asked Questions

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Last updated: 2025-02-20

All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.