Prob obv Q&A - ...
 

  You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more

[Closed] Prob obv Q&A - Can you put 30mm bearings in a 24mm BB cup? WMfG - New Cranks

9 Posts
9 Users
0 Reactions
949 Views
 Sui
Posts: 3107
Free Member
Topic starter
 

I probably know the answer to this is no, but i don't have a BB30 cup to measure/look at vs the 24mm HTII cups that i've got... So is the outer bearing size on a 24 the same as a 30?

It's new crank time, and i'd like something a bit shiny, but they all appear to have over-sized spindles, either 29 or 30mm. I've got a fairly new Wheels Mfg BB in and it pains to think it (the cups at least) will now be redundant..

ta


 
Posted : 22/01/2021 11:45 am
Posts: 2684
Full Member
 

Can't think of a solution that would work for that problem. Either stick to 24mm cranks or get a new BB with your new cranks.


 
Posted : 22/01/2021 12:03 pm
Posts: 157
Free Member
 

Would appear not
Hope 24mm spindle bb takes bearing od of 37mm, where my 30mm spindle e13 takes a bearing od of 42mm


 
Posted : 22/01/2021 1:53 pm
Posts: 28475
Free Member
 

What qualifies as a 'shiny' crank? Is XTR not going to cut it?


 
Posted : 22/01/2021 1:58 pm
Posts: 137
Free Member
 

sui, i think you should get new cranks AND bb and i'll look after the old bb for you.....

cheers

Iain


 
Posted : 22/01/2021 1:58 pm
Posts: 0
Free Member
 

No you can't I'm afraid but bear in mind 30mm BSA bottom brackets are rubbish, or more to the point, 30mm spindles are a bad idea in bsa shells as there simply isn't enough room.
If you need proof they're a bad idea, even sram, purveyors of GXP, a bar so low its recessed, say the bearing life is unacceptably poor in bsa 30.


 
Posted : 22/01/2021 2:07 pm
Posts: 13134
Full Member
 

Probably got the wrong end of the stick.

https://www.probikekit.co.uk/bottom-bracket-cups-spares/rotor-bsa-30mm-bottom-bracket-converter-steel/11529976.html?affil=thggpsad&switchcurrency=GBP&shippingcountry=GB&shoppingpid=COMPO10_030518_&&thg_ppc_campaign=71700000077028938&gclid=Cj0KCQiAjKqABhDLARIsABbJrGk1ZE7smz7zmeibiHabOQGHkCmZalSe4dqVdQ3gDRvxucMh73vZKu0aAvISEALw_wcB&gclsrc=aw.ds

These are for putting a 30mm crank into an external BSA24 threaded bottom bracket. Got them on a couple of road frames. Don't have the greatest longevity (the walls are v thin - I think it's normally clumsy diy mechanics that cock it up) reputation but mine have been fine.


 
Posted : 22/01/2021 2:09 pm
Posts: 699
Full Member
 

Praxis M30 does the same job I think. I have that on one bike with a Praxis 30mm spindle in a threaded BB shell.

Bearing life hasn't been great but I think that's because of the bearings specced (LLB seals for lower friction but I suspect they seal less well), plus I suspect had I popped the seals off and greased before winter they might've been fine.

I can see that the structure is compromised and therefore less strong but not sure I see why it'd increase bearing wear.


 
Posted : 22/01/2021 2:25 pm
Posts: 4696
Free Member
 

If you need proof they’re a bad idea, even sram, purveyors of GXP, a bar so low its recessed, say the bearing life is unacceptably poor in bsa 30.

They only said that to promote their new DUB size of 28.99mm. From my experience my 30mm BB's - RaceFace - have lasted just as long as my Shimano 24mm ones.


 
Posted : 22/01/2021 2:32 pm
 Sui
Posts: 3107
Free Member
Topic starter
 

Cheers all, I did think there would be someone kind enough to take the old ones of my hands 😉. I was looking at some hopes hence the 30mm spindle, as I want either red or silver cranks, granted my ancient SLXs are almost silver now, but it's bike to work time so treating myself..


 
Posted : 22/01/2021 7:48 pm

6 DAYS LEFT
We are currently at 95% of our target!