How do I know what cable length to buy?

Brake and gear cables come in standard lengths (usually 1100 mm and 2100 mm). This calculator helps you determine whether standard lengths will work or if you need longer ones.

Should I cut cables to exact length?

Always leave 20-30 mm extra beyond the anchor bolt. For outer housing, cut cleanly with proper cable cutters (not pliers) and ensure the ends are filed smooth.

Does internal routing need longer cables?

Yes, typically 100-200 mm longer inner cables because the routing through the frame adds extra distance compared to external routing.

How often should cables be replaced?

Brake and gear cables should be replaced every 3000-5000 km or when shifting becomes sluggish. Outer housing can last 5000-10000 km if kept clean.

What about electronic groupsets?

Electronic shifting (Shimano Di2, SRAM eTap, Campagnolo EPS) does not use gear cables. You still need brake cables unless you have hydraulic disc brakes.

BikeCalcs

Cable Length Calculator — Brake & Gear Cable Lengths

Calculate brake and gear cable lengths for your frame size and setup.

Frame Size

Handlebar Type

Cable Routing

How We Calculate This

Cable Length Estimation

Base lengths for a 54 cm frame: Front brake ~900 mm, Rear brake ~1750 mm, Front derailleur ~1200 mm, Rear derailleur ~2100 mm
Frame size adjustment: ~20 mm per cm difference from 54 cm
Handlebar type: Flat bars ~100 mm shorter than drop bars
Internal routing: Adds 100-150 mm for cables routed through the frame

Frequently Asked Questions

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Last updated: February 2026

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