I need to replace the BB92 on my Commencal.

Despite using the correct removal tool (BBT-90.3) and a hefty hammer, no amount of persuasion is working and I’m worried that I might actually knock out the inner race only leaving the outer race and BB shell still in the frame.

I’ve used heat/blow torch on bearings in motorcycle frames/wheels and it works a treat but I’m not sure about doing this on a bicycle that has a much thinner frame.

So before I set fire to the bike/myself/my flat, can anyone suggest an alternative removal method?

a plastic shimano bb92?

is the frame supported while you’re hitting the tool?

Soak a tea towel in boiling hot water (or heat wet one in microwave) and wrap around the bb area.
Then belt sh1t out of it (getting them out intact is a different matter).

Just accept you’re going to trash-it by removing it – get a bigger hammer!

helpful1

a plastic shimano bb92?

It’s a plastic GXP one.

helpful1

is the frame supported while you’re hitting the tool?

Not brilliantly. The frame is lying, on its side, on a couple of blocks of wood positioned as close as possible to the BB whilst allowing sufficient space for the bearing to fall out.

Rorschach

Soak a tea towel in boiling hot water (or heat wet one in microwave) and wrap around the bb area.
Then belt sh1t out of it (getting them out intact is a different matter).

Is that going to be warm enough to get the frame around the BB to expand slightly? I seem to recall being told that aluminium (or possibly alloy) starts to expand at around 80degC though I’ve no idea if that’s true.

dovebiker

Just accept you’re going to trash-it by removing it – get a bigger hammer!

Happy to trash the current BB but my concern is if I knock the inner race out (the same race which the BB tool engages with), how do I then get the outer race and plastic shells out?

The think the hot water thing works more by softening the plastic than expanding the ali.That said I’ve used it a lot (despite my initial scepticism) over the years (lbs spannerer) in lots of different situations and it seems to work more often than not.
Once the bearing race comes out (with the plastic lip) you can push the inner sleeve out of the way and the remaining cup usually comes out very easily.

Rorschach – Member

The think the hot water thing works more by softening the plastic than expanding the ali.That said I’ve used it a lot (despite my initial scepticism) over the years (lbs spannerer) in lots of different situations and it seems to work more often than not.
Once the bearing race comes out (with the plastic lip) you can push the inner sleeve out of the way and the remaining cup usually comes out very easily.

Thanks will give it a try. I’m a big advocate of using heat instead of brute force, especially where threads can pick up road crap and you have to re-use those bolts again (brake disc bolts, exhaust header bolts).

http://www.unior-bike.com/?doc=10780&prod=303784
I’ve got one off these that works well on my commencals, but have used just a tapered length of wood and a hammer, in a bike stand, takes quite a firm smack, the bearing usually comes flying out in one piece. A bit of heat won’t do any harm but I’ve never needed any and swapped at least 5 out. If you near Leeds happy to lend a hand.

blairc70 – Member

http://www.unior-bike.com/?doc=10780&prod=303784
I’ve got one off these that works well on my commencals, but have used just a tapered length of wood and a hammer, in a bike stand, takes quite a firm smack, the bearing usually comes flying out in one piece. A bit of heat won’t do any harm but I’ve never needed any and swapped at least 5 out. If you near Leeds happy to lend a hand.

Thanks mate, am miles away in Bromley, south London otherwise I’d have taken you up on the offer. 🙁 🙂

they’re reasonably soft plastic so ‘should’ come out pretty easily, if not just bash out the bearings, and cut the outer race with a junior hacksaw.

No sweat chap, if its a V4 the hope bb fits and works well and lasts (with my sram cranks). If its the V3 then choices are a bit limited.

A very brief update, managed to get the bearings out and in one piece too. The solution:

dovebiker

…..get a bigger hammer!

A heavier hammer and not pussying around did the job. Had a blowtorch on standby but it wasn’t needed. 🙂

Getting the new BB in squarely was much more of a PITA but a little patience brought success. Feeling quite chuffed with myself now. 😀

Thankfully my BB92 popped out with ease (shop fitted incorrect shimano bearing), and I used my headset press to fit the new cups in.