Post by kidrob on Wed Sep 13, am. Post by gewichtweenie on Wed Sep 13, am. Post by Kurets on Wed Sep 13, am.
The bottom bracket, or 'BB' as it often gets shortened to, is the humble bearing which supports the rotation of the cranks. This out of the way components tucked mostly out of sight between the crank arms has morphed to include nearly a dozen different styles and sizes. Even so, the traditional threaded BSA threaded version remains the most popular, and for good reason, it works and is easy to fit so this guide concentrates on this type.
In more than 10 years of wrenching for pros and even more years as a bike shop mechanic, I've learned a few things about bottom bracket repair. Most of the time, the true cause is a loose chainring bolt. Tighten 'em up and that'll quiet most creaks.
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Bottom bracket service falls into one of two categories: you either change them with a new one or exchange bearings. Other brands do sell replacement bearings or seals to get the job done. Bikes with threadless bottom brackets PF30 or similar require you to punch out your old bearings using a BBT
The bottom bracket is what allows your cranks to turn. If your cranks are wobbly, or there's a noise coming from between your cranks when you pedal, then you may need to overhaul your bottom bracket. This instructable a remix of FriendofHumanity's 'ble will show how to remove, clean, lube and adjust most adjustable bottom brackets using only common hand tools and one "special" tool.
Begin by removing the cranks. Watch the cotterless crank removal tutorial for a more detailed procedure. Once the cranks are removed, loosen and remove the lock ring on the non-drive or left side of the bike by turning counter-clockwise.