Cable Length Calculator — Brake & Gear Cable Lengths

Inner wires come in standard lengths. Brake inner wires are usually sold as a universal ~1700 mm wire (one length for either brake) or as a front/rear pair of ~1000 mm and ~2050 mm (e.g. the Shimano universal set). Gear/derailleur inner wires are ~2100 mm. These standards are long enough for almost any frame, so you buy the standard length and cut to fit — this calculator estimates the finished length so you know roughly how much to trim.

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.

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

Replacement is condition-driven rather than a fixed interval. Gear inner cables typically last anywhere from ~3000 km to 10,000 km or more; brake inner cables usually last much longer, often two or more years. Replace any cable sooner if you see fraying strands, feel stiff or sluggish movement, or notice shifting/braking that no longer responds cleanly. If you ride all year in wet and grit, a yearly cable-and-housing refresh is sensible.

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