How to Remove & Replace a Sealed Cartridge Bottom Bracket | Halfords UK

Is your bike bottom bracket creaking? Maybe it needs a bottom bracket removal?
Watch our handy video about your bike’s bottom bracket tool to learn how to replace it yourself!

Halfords Basic 6 Piece Allen Key Set
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Bikehut Professional Crank Extractor
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Super B Bottom Bracket Remover ISIS-20 Truvativ
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Bottom Bracket Range
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Bikehut Premium Pedal Spanner
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Here’s a quick guide on replacing a square taper bottom bracket.

To do this, you’ll need: An 8mm Allen key, Crank extractor tool, Bottom bracket removal tool, a replacement bottom bracket, A torque wrench and Lube or grease.

The bottom bracket is the axle that runs through the central point of the bike where your cranks are attached. If it’s damaged, worn or loose, it can damage your bike frame and gear set, as well as giving you a rougher ride and risking your safety.

To check your bottom bracket, grab either side of the cranks and give them a quick shimmy. If you see or feel movement, it’s time for a replacement.

We’ll start by removing the crank bolts. Sometimes these are 14mm hex points that need a socket for removal, but for now, we need an 8mm Allen key. Get your Allen key and begin removing the bolt - like so. Do this again on the other side, making sure to keep your bolts in a safe place for re-assembling later on.

Now you have the crank bolt off, it’s time to remove that crank. For this you need the dual-component crank extractor tool. One component, the lock-in nut, goes into the thread of the crank arm, like so. Ensure it’s threaded correctly so as not to damage your crank threading. Once it’s finger-tight, insert the other part of the crank extractor, and tighten it. Use the crank to apply opposite pressure, as I’m doing, and gradually tighten it until you feel the crank is ready to come off.

Now, repeat this process on the other side. You’ll then have both your cranks off. Brilliant! Now it’s time to remove your bottom bracket. At this point grab your bottom bracket removal tool.

Put this into the cartridge system and twist it either clockwise or anti-clockwise – it depends on the threading on your bike. The drive side will be reverse thread and the non-drive side is an anti-clockwise rotation to undo. It can be stiff so may need a fair amount of pressure. Once this part is removed, put it to one side so you can measure it and ensure you’re getting the right replacement. Repeat this on the other side.

Now you’ve removed the bracket, inspect the threads to ensure they’re still intact. You can also take this opportunity to lube, grease and clean the bottom bracket’s inside threading. This will help you insert your new bottom bracket.

Insert your new bottom bracket, observing the ‘L’ and the ‘R’ on the component – these illustrate which way to insert the bottom bracket, grease the threads and slide it into the gap like this. Then, loosely tighten into place on the drive-side. Once that’s in, pop your non-drive-side cuff on the opposite side of the bottom bracket and tighten loosely.

Once they’re both loosely attached, it’s time to use your bottom bracket tool to tighten both sides firmly, starting with the drive-side first. Once you’ve done both sides, and you’re happy they’re tightened adequately, it’s time to re-fit your crank set.

We’ll start with the non-drive-side crank arm. With a square taper, make sure one crank is at 6 o’clock and the other at 12 o’clock. The best way to tighten the crank is with a torque wrench. Use this by setting the wrench to the recommended newton meters. You can find this recommendation in your owner’s manual, or if you’ve lost it, online, for both your bottom bracket and crank set. On this bike it’s XX Newton Meters. Once you hear a click from the torque wrench, you’ve adjusted to the correct tension.

Then, put your other crank on the drive-side, hook the chain into the chain set, and place the crank at 12 o’clock. Set your torque wrench and again, tighten up the crank bolt to the correct tension. Once you’ve done this, run your crank reel backwards ensuring free movement of the bottom bracket. Then, give your crank arms a final shimmy and check for no movement.

Once you’ve done that, you’ve completed your bottom bracket replacement.

If you’d like help or guidance or any other bike repairs, pop in store at your local Halfords and speak to a member of our professionally trained team.