Seized Square-Taper Bottom Bracket Removal, the Knuckle-friendly Way.

This is a simple home-made tool to remove a bottom bracket that refuses to budge. So simple, I'd be surprised if somebody else hasn't already come up with this. But, I couldn't find it on the internet, so here we are.

I'm going to assume that you're reading this because you've already removed the cranks and failed, via the normal method to remove the BB cups because they're proper stuck in there; you've skinned your knuckles turned the air blue and caused your neighbour to cover their kids' ears -so we can skip right ahead.

If you can, get some penetrating oil spray around the cups the night before. I forgot to, and this technique still worked fine, but it will help if your BB is worse than mine was.

You will need:

1. BB tool (must be open-ended, to pass a bolt through) I've used the X-tools BB tool (£4.45 from Wiggle.co.uk) because it's short (so the force is applied as close the frame as possible), open-ended (for the bolt) and has a large hex head for a large spanner, for leverage.
2. 32mm spanner (or whatever your BB tool requires)
3. M8 bolt, at least 60mm long and with a 1mm thread pitch (1mm pitch is crucial)
4. nut to fit the bolt
5. 3 or 4 wide washers, wider that the BB tool
6. adjustable spanner (or a fixed one sized to the nut)
7. copper grease (regular grease will do, but copper grease is the best anti-seize)
8. penetrating oil and some rags

The bolt must have the same thread as your crank bolts, so it'll screw into the BB spindle where your crank bolts normally go. If you have a tool to do so, measure your crank bolt to double check that it is M8 & 1.0 mm pitch, if it's different, you simply need to match the bolt for this tool to your crank bolt's thread.

I found that M8 bolts tend to have a 1.5mm thread pitch, which will not do. For most BBs you need 1.0mm thread pitch. If you're not sure, hold a crank bolt against your bolt, if the threads marry-up nicely, you're good, it'll be obvious.

Apply a little grease to the bolt thread.
Thread the nut, up along the bolt, to the head and then slide on a couple of washers (one will bend, so use at least two).
Hold your BB tool against the splines and push the bolt (through the BB tool) to the thread in the spindle, screw the bolt into the BB spindle to get a firm hold (you might need to hold a crank arm on the other side to stop the spindle rotating).

Tighten the nut so it pulls the tool firmly into the splines on the BB cup. This solid connection is what makes the tool work.

Literally; put your weight into it. With the tool firmly threaded into the BB spindle, it won't slip and the splines will not be damaged. If that's not enough leverage, you can use a pipe (scaffold tube does nicely) over the spanner to give you extra leverage.

Do the Non-Drive Side (NDS) first.

Remember: the two sides have opposing threads! Generally the left (non-drive) side has the usual RH thread, but the drive side is a left-hand thread. It's easy to remember this: for both sides, with the wrench vertical, push it in the forwards direction and you'll be turning it the correct way to loosen.

This image shows half the BB coming out from the NDS. Whoops! I guess this shows how well the tool grips the cup as it ripped the spindle from the bearing and cartridge which remain inside the shell. Not a big deal as the BB's getting tossed anyway.

In hindsight; a better method for the NDS, would be to loosen the nut on the bolt as you turn the big spanner, to account for the non-fixed cup wanting to move away from rest of the BB, into which your tool is pulling it. You could probably even strap the two spanners (one on the tool body and one on the nut against the washers) -as the thread pitch is the same, one full turn will move them both the same distance (1mm) laterally. This should ensure you don't pull the spindle out the wrong side, as you can see I did here.

For the drive side, there's no need to loosen the nut, as that cup is fixed to the BB cartridge and the spindle will not want to stay put.

Clean all of the rust and crap from the shell. Clean it really, really well. When you rub in the grease, rub it all over the interior as rain water will get in there.

The copper grease prevents it seizing again.

The BB tool slipping-out is a right pain in the arse. You can use this for installation of your new BB, as well as extraction. Never skin your knuckles again and your neighbour won't hurry their kids inside when they see you working on your bike.