Cranksets

Crankset Buying Guide

The crankset is the lever arm between your feet and the chainring. Crank arm length, spindle interface, and chainring compatibility all affect performance — and unlike most components, the crankset directly interacts with three other parts (bottom bracket, chainring, pedals), so compatibility matters at every connection point.

Crank Arm Length

Standard MTB crank arms are 170mm or 175mm. Shorter cranks (165mm, 160mm) have become popular for DH and enduro — they provide more ground clearance, reduce pedal strikes on rocks, and allow a slightly lower bottom bracket height without penalty. The power difference between 170mm and 175mm cranks is negligible for most riders. If you clip pedals frequently on rocky trails, going to 165mm cranks solves it mechanically rather than changing your pedalling style.

Spindle Interface

The spindle passes through the bottom bracket and connects the two crank arms. Shimano Hollowtech II uses a 24mm hollow steel spindle integrated into the right (drive-side) crank arm. SRAM DUB uses a 28.99mm alloy spindle. Race Face Cinch uses a 30mm spindle compatible with RaceFace and Easton cranks. Hope uses a 30mm spindle with their own crank design. The spindle interface determines which bottom bracket you need — these are not interchangeable.

Material

Alloy cranks (forged 7050 or 7075 aluminium) are strong, stiff and relatively affordable. Shimano SLX and XT alloy cranks are excellent. Carbon cranks save 50-100g per pair but cost significantly more and can be damaged by rock strikes. For trail and enduro riding, alloy cranks are the pragmatic choice — the weight saving of carbon isn't worth the increased vulnerability to impacts. Carbon cranks make more sense on XC race bikes where they're less exposed to rock strikes.

Boost Spacing

Boost cranks use a 3mm outward chainline offset compared to non-Boost — this matches the wider Boost hub spacing (148mm rear, 110mm front) that's now standard on MTBs. Running a non-Boost crankset on a Boost frame shifts the chainline inward, causing poor chain alignment with the outer cassette sprockets. Most modern cranks are Boost-compatible or Boost-specific. If you're running a non-Boost crank on a Boost frame, a 3mm chainring spacer or a Boost-specific chainring fixes the chainline without replacing the whole crankset.