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Press-fit 30 bottom brackets that fit Dura-Ace axle WITHOUT adapters...

4K views 7 replies 5 participants last post by  JoelS 
#1 ·
....ie directly. Everyone makes pf30 with adapters to fit shimano 24mm axles. I dont want to use adapters because I want to avoid the addition of another interface of surfaces that may be a source of creaking.

So, are there any bottom brackets out there that fit pf30 bottom bracket shells and directly fit Shimano 24mm axles?
 
#2 · (Edited)
google gave me this....threaded too

Product Lens Text Photograph Line


and this

Product Lens Camera lens Cameras & optics Camera accessory
 
#3 ·
The only way it will work is with adapters ... With a PF30 every crank will need an adapter of some sort.

With that said ... I have a Praxis adapter on my cross/commuter bike that works much, much, much better than the stock cups. I have nearly 1500 miles on it with no creaking.
 
#4 ·
Agreed. It's sometimes hard to understand with OP's like this. Who post a couple of times and then dissapear. Who don't appear to know about google searches. Or thank you.

Every single BB system ever made "adapts" the BB shell of the frame to accept a crank.

The ones I showed do it in a fairly solid and direct way in answer to the OP's question.
 
#6 · (Edited)
Here's my concern with the Praxis Conversion PF30 to 24mm bb: while connecting the two bearing cups is clearly a superior design, it should be noted that the drive-side collet that will expand to press against the frame's bb shell will not provide much of a positive seat against the frame. Here's why: as I understand it, as you screw in the drive-side bearing cup,the collet is going to be wedged open and thus press against the frame. But the problem is that the collet will be wedged open in an angular fashion (kinda like a Park Toolz headset bearing cup remover), and thus, only the tip of the collet will rest against the BB shell. In contrast, the non-drive-side cup will contact the frame along the entire length of the skirt (ie the part that's pressed into the BB shell), which provides a more positive seat against the frame.

Paxis is on the right track, but I don't think they've quite got it yet.

It's really a shame that component manufacturers have to scramble to provide 'solutions' to fabulously idiotic designs like press-fit bottom brackets, when NONE of the problems we're facing with them existed with threaded bottom brackets to begin with.
 
#7 ·
I think you've stated a theoretical concern based on looking at drawings and dimensions. What you haven't included is anything about the forces that the praxis sees. And of course its a purely theoretical academic exercise since I have never seen any reports of problems with it in the real world. We've got a couple of people on cannondale evo's here with them and after a whole season of mileage they are smooth and silent.
 
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