Bottom Brackets
Used bottom brackets connect the crankset to the frame, and the standard you need is set by both parts at once. Threaded BSA/English (68mm shell, 1.370" x 24tpi) is the traditional standard and the easiest to maintain, while press-fit systems take larger bearings and T47 combines press-fit dimensions with threaded installation. Match the BB to your crankset, not your frame alone.
Threaded or press-fit?
Threaded standards screw into the shell and stay put. BSA/English uses a 68mm shell with threaded cups and fits 24mm (Shimano), 30mm (SRAM DUB/Campagnolo) or other spindle sizes with the appropriate cups — the most reliable and serviceable option. Italian threading uses a 70mm shell with right-hand thread on both sides and is found on Italian frames. T47 puts threaded cups in a 68mm shell with a 47mm bore, giving press-fit bearing sizes with threaded security. Press-fit systems were designed to accommodate larger bearings and stiffer cranks, but they are notorious for creaking.
Which press-fit standard is which?
BB86 uses an 86.5mm shell with a 41mm bore and pressed-in bearings — the most common press-fit on carbon frames. PF30 uses a 68mm shell with a 46mm bore, taking larger bearings but proving more creak-prone. BB386EVO combines an 86.5mm shell with a 46mm bore for a wide, stiff platform. The shell width and bore diameter are what you measure; get both right and the rest follows.
Will it fit my crankset?
Shimano Hollowtech II uses a 24mm spindle and has the widest BB compatibility. SRAM DUB uses a 28.99mm spindle and requires DUB-specific BBs. Campagnolo Ultra-Torque uses a split 25mm spindle with a unique hirth joint. You cannot mix spindle sizes, so check the crankset before the frame and keep it consistent with the rest of your groupset. Aftermarket BBs from Wheels Manufacturing, Chris King and Hope offer higher-quality bearings in all standards, and ceramic bearings (CeramicSpeed, Kogel) claim marginal friction reduction at significant cost.
How do I stop a press-fit bottom bracket creaking?
Press-fit BBs creak because the bearing cups can micro-move in the shell. Threadless BB adapters (Wheels Manufacturing, Hambini) convert press-fit shells to threaded, retaining compound such as Loctite 641 secures cups, and proper installation with a press tool rather than a mallet prevents damage. BSA and T47 BBs rarely creak because threaded engagement prevents movement. If you're 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, so rule them out before you start chasing noises through the rest of your components.
What should I check buying used?
BBs are consumables and bearings wear out. Spin the cranks without the chain and feel for roughness or play — any grittiness means the bearings need replacing, at £10-30 for standard bearings and £50+ for ceramic. Press-fit BBs should be checked for correct seating, as partially pressed cups can creak and damage the frame shell. On 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, as the bearings are replaceable and the shells last indefinitely — the same logic that makes quality pedals worth picking up second-hand.