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Bottom Brackets

The bottom bracket connects the crankset to the frame. Threaded BSA/English (68mm shell, 1.370" x 24tpi) is the traditional standard and easiest to maintain. Press-fit systems (BB86, PF30, BB386EVO) were designed to accommodate larger bearings and stiffer cranks but are notorious for creaking. T47 is the newer threaded standard that combines press-fit dimensions with threaded installation. Shimano, SRAM, and Campagnolo each use specific spindle standards — match the BB to your crankset, not your frame alone.

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Buying Guide

Road Bottom Bracket Buying Guide

Standards Explained

BSA/English: 68mm shell width, threaded cups, fits 24mm (Shimano), 30mm (SRAM DUB/Campagnolo), or other spindle sizes with appropriate cups. The most reliable and serviceable standard. Italian threading: 70mm shell, right-hand thread both sides — found on Italian frames. Press-fit BB86: 86.5mm shell, 41mm bore, pressed-in bearings — the most common press-fit on carbon frames. PF30: 68mm shell, 46mm bore — larger bearings but more creak-prone. BB386EVO: 86.5mm shell, 46mm bore — wide and stiff. T47: threaded cups in a 68mm shell with 47mm bore — the best of both worlds.

Spindle Compatibility

Shimano Hollowtech II uses a 24mm spindle — the widest BB compatibility. SRAM DUB uses a 28.99mm spindle — requires DUB-specific BBs. Campagnolo Ultra-Torque uses a split 25mm spindle with a unique hirth joint. You cannot mix spindle sizes — a Shimano crankset needs a 24mm BB, SRAM needs DUB, Campagnolo needs Ultra-Torque. Aftermarket BBs from Wheels Manufacturing, Chris King, and Hope offer higher-quality bearings in all standards. Ceramic bearings (CeramicSpeed, Kogel) claim marginal friction reduction at significant cost.

Dealing with Creak

Press-fit BBs creak because the bearing cups can micro-move in the shell. Solutions: threadless BB adapters (Wheels Manufacturing, Hambini) convert press-fit shells to threaded; retaining compound (Loctite 641) secures cups; proper installation with a press tool (not a mallet) prevents damage. BSA and T47 BBs rarely creak because threaded engagement prevents movement. If buying a frame with press-fit, budget for a quality BB — cheap press-fit BBs are the number one source of creaking on modern road bikes.

Buying Used

BBs are consumables — bearings wear out. Spin the cranks without the chain and feel for roughness or play. Any grittiness means the bearings need replacing (£10-30 for standard bearings, £50+ for ceramic). Press-fit BBs should be checked for correct seating — partially pressed cups can creak and damage the frame shell. Threaded BBs: check the cups aren't seized — aluminium cups in steel or titanium shells can galvanically corrode if not greased. Used Chris King BBs are worth buying — the bearings are replaceable and the shells last indefinitely.