Cartridge Bottom Bracket Removal

Cartridge bottom brackets started to replace the adjustable types back in the late 80s/early 90s, so these are much more common on bikes with indexed shifting. If the bearings have a ton of play or make clicking sounds as you pedal, then the bottom bracket is toast. I can show you how to remove and replace a cartridge bottom bracket in this little tutorial. First you need a crank puller, a bottom bracket tool, and something to remove the crank bolts (this procedure is impossible without the right tools, but very easy if you have them). You'll probably also want a nice big wrench or breaker bar for leverage with the bottom bracket tool. Well let's get started:

First remove the crank bolts. This bike uses 8mm Allen bolts (a 5/16" Allen key also fits, but might strip them under high torque due to their looser fit).

Now with the bolts removed you can see the threads for the crank puller to screw into:

Thread the crank puller all the way in and remove the cranks:

Now it's time to use the bottom bracket tool. It's a large tool with 20 splines to fit most bottom brackets (there are exceptions like Phil Wood or Shimano Dura-Ace/XTR, these need something special). I like to put a big 15/16" box end wrench on the tool, but use whatever you like for leverage. I loosen up one side first:

Then remove the other piece:

Keep in mind that the drivetrain side is probably reverse threaded. Now just remove the piece remaining in the frame (I don't think it matters which piece you remove first) and you're done. Here are all the pieces that I removed (along with the tools I used):

The bearings in these cartridge units are generally not serviceable, so you just replace the whole cartridge if they go bad. Here's what the bearings look like with the dustcap removed:

A replacement bottom bracket goes in the opposite way, just clean and grease the frame's threads and put lots of torque on the main piece. The little plastic cup on the other side only needs to be snug tight. You shouldn't have to adjust anything, provided that you used the same size replacement.



There are 3 variables when buying a replacement bottom bracket: thread size, bottom bracket shell width, and spindle length. Most frames are English threaded (1.375"-24tpi) with 68mm wide shells (some mountain bikes have 73mm shells, and Italian frames are 70mm). Your crankset, however, determines the spindle length instead of your frame. Remove your bottom bracket and measure it to verify all of its dimensions before you buy another one to be sure you get the right size replacement.