Bottom Brackets come in a variety of sizes, types and tapers, each manufacturer clearly specifies which Bottom Bracket type would be compatible with their Chainsets and details are included in the product descriptions on our website so this makes choosing the right BB easy. The manufacturer's guidelines will also provide you with the correct chainline based on a standard rear hub width, so it is important to follow these recommendations in terms of size/type, however you can obviously choose a different brand should this be desirable.

The main issue should be with the thread on your frames BB Shell (where the BB connects to the frame), this will either be BSA (British thread) or Italian thread, BSA is 68mm standard whereas Italian is 70mm but again check the manufacturers guidelines for your frame and product descriptions on our website for the frame bb shell type and bb type.

Octalink Bottom Brackets

This system, designed by Shimano, was the first successful alternative to the older square taper. The Octalink system uses a larger and stiffer spindle with eight splines. The splines provide a greater contact area between crank and spindle for a stiffer interface. Octalink exists in the marketplace in two variants, Octalink v1 and Octalink v2.

The difference between the two can be seen by the depth of mounting grooves on the bottom bracket spindle. XTR, 105, Ultegra 6500 and Dura Ace 7700 cranksets mate to version one bottom brackets, while later mountain bike designs use the deeper-grooved version two. The system is proprietary and protected by Shimano patents and licence fees, thus relatively few companies aside from Shimano produce Octalink cranksets. While some competitors to Shimano (especially Campagnolo) continued to use the older square taper, others worked together to create a similar ISIS design as a free alternative. Although Octalink is a successful and reliable three-piece system, Shimano's newer two-piece systems integrate the spindle onto the right crank arm.