Technical numpty he...
 

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[Closed] Technical numpty help please - Bottom Brackets

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Hi

I have two road bikes. The first - a Bianchi - has a Praxis M30 BB replacing a BB30 within which an Infocrank was installed.

The second, my Boardman TT bike has an FSA PF30 BB & crankset.

Now, an LBS has told me the Praxis cannot go in the Boardman. However, I think it can and cannot see any measurable detail as to why not EXCEPT I don't have the PF BB Sleeve as shown on the Praxis site - but I could purchase this.

If I had the sleeve for the Praxis BB and therefore Infocrank would fit the TT bike - right?

Praxis M30 BB showing sleeve for PF30 - https://www.praxiscycles.com/product/m30-conv-bb30-pf30/
Praxis PF30 sleeve - https://www.praxiscycles.com/product/pf30-sleeves/
FSA PF30 as indicated is in my Boardman - http://www.fullspeedahead.com/products/bottom-brackets/road-bb-pf30-bottom-bracket/

Its a mystery to me why I'm being told "can't" - what am I missing?


 
Posted : 15/03/2017 4:05 pm
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Pleeeease?


 
Posted : 15/03/2017 6:40 pm
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PF30 and BB30 won't mix - PF30 had an OD of 46mm whereas BB30 is 42mm:

[url= ]BB Compatibility Chart[/url]


 
Posted : 15/03/2017 7:07 pm
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Firstly, PF30 and BB 30 are two slightly different animals..... if I recall correctly PF30 is a tad bigger. (EDIT, beaten to it!) Specailized love them.
If you fit that sleeve you'll essentially end up with 2 pressfiitted things inside each other - Could be creaktastic!
All you need to know is that these things are only as good as the bearings you put in them. All Praxis do is make some sort of sleeve to push someone elses bearing into, for example.
Personally, I wouldn't complicate the issue, I'd just buy decent bearings and stick with what you have.
yes, you can replace the bearings in and ordinary PF30BB. I've done it.
If you really want something better get a Wheels Manufacturing one, the cups last longer than plastic when removing/replacing the bearings and you won't have 2 things pressed inside your frame.


 
Posted : 15/03/2017 7:08 pm
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Well, Praxis say a praxis spindle must go on a Praxis M30 BB - but the they would wouldn't they.

So it will work with the PF30 sleeve is the conclusion.


 
Posted : 15/03/2017 8:27 pm
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Yes the sleeve should allow your info crank and m30 bb to fit a pf30 shell.

To fit a praxis bb to any pf30 frame you end up useing the sleeve anyway.

And we fit plenty of the praxis pf30-24mm Shimano converter BBs. They all have that sleeve and do t often creak , just use some copper slip as shown on the praxis website

The m30 cranks have 30mm/28mm dia axle so won't fit normal bb330/pf30 bottom brackets


 
Posted : 15/03/2017 8:42 pm
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Oh... the cranks spindle is tapered? That's the piece of puzzle I've missed!

Thanks.


 
Posted : 15/03/2017 9:07 pm