Help: Bearing removal on Praxis BSA 30 (M30 BB)

Discuss light weight issues concerning road bikes & parts.
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taylorpetie
Posts: 48
Joined: Tue May 19, 2015 4:55 pm
Location: California

by taylorpetie

I have a Praxis Works M30 BB (https://praxiscycles.com/product/m30-english-threaded/) and I've been searching for a way to replace/remove the bearings. If someone has done this please advise. I've been looking for a bearing pull tool for this thing. Seems the bearings are flushed and there's no leverage to knock out the bearings.

Alternatively: is there a way to remove the BSA female thread located on the BB frame if there is no way to replace the bearings?

This is on my daughter's specialized Ruby frame. Thanks.

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LePouletTrapu
Posts: 27
Joined: Tue Nov 13, 2007 1:19 pm
Location: Scotland, UK

by LePouletTrapu

You need a blind bearing puller, if you Google them there are plenty available which should fit. They basically expand inside the bearing with a very small lip on the back and then use a slide hammer to pull them out. I'm in the process of ordering one to do the same thing however price is higher than replacement cups etc and you will want a bearing press to reinstall the new cartridge bearings. If you're planning on doing this a few times and you have the tools it makes sense. I've just done a similar thing on my Rotor Pf30 cups and it worked a treat.

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sungod
Posts: 1539
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

generically, you should be able to get a screwdriver/drift through from the opposite side onto the edge of the inner race and go around the edge gently tapping out the bearing

'proper' tools that should be able to extract the bearings it would be a headset cup remover or blind bearing tool

you'd need to source correct bearings to replace, then get or improvise a press to get the new bearings in (large bolt + nuts, plus thick washers (using the old bearing outer race to press the new bearing in)

by "is there a way to remove the BSA female thread located on the BB frame if there is no way to replace the bearings", do you mean remove the bb from the frame? unless you've a bb tool that fits, looks like you'd need to get the praxis tool https://praxiscycles.com/product/m30-tool/

are you certain the bearings are really shot? first step i'd take would be use a pick to carefully remove the outer seals, flush out all the old grease/dirt with spray solvent, spin them to see if they rotate freely without roughness or play, if ok pack with marine grease and pop the seals back on

alcatraz
Posts: 921
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Whats the inner diameter of the bearing? I don't know about bb bearings larger inner diameter but for smaller bearings I saw a genius idea on youtube. It's to use something the youtuber called a "magnabolt", simple tool you find in the hardware store. I think it's used as an anker in concrete walls.

You buy one with the correct inner diameter and expand it in the bearing. Then knock the bearing out without having to hit a tiny exposed inner race. You'll have the magnabolt to knock against from the other side.

/a

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