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About BB92 spacers

Old 06-25-20, 03:43 AM
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Amt0571
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About BB92 spacers

I have a BB92 bike that requires a 2.5mm spacer on the bottom bracket right cup. This means the right cup is not fully inserted to the frame (the spacer prevents that), and it seems the nylon of the cup gets crushed or deformed with time until it comes loose and creaking starts. That doesn't surprise me, as the cups seem to have a hollow indent on the internal part of the "lip" that contacts the frame. When I insert a new cup everything seems ok, it fits tight and all, but after a while it starts feeling loose (feels loose when disassembling the crank, not while riding) and creaking starts.

I really don't understand why BB92 with a 89.5mm shell is meant to work like that (well, I don't understand why 89.5mm shells exist in the first place, but I can't change that). Wouldn't it be better to press the cup all the way in without the spacer, making the contact area bigger and the attachment way more solid, like on the left cup that works perfectly well, and place a 2.5mm spacer on the spindle itself, between the bearing and the crank arm?

Why the hell isn't this the "official" way to mount it? I'm going to try it, but first I would like to know if there is any downside with this approach as it seems such an easy solution that I can't get my head around the idea that Shimano hasn't thought of this.

PD: press fit is a piece of crap. Period. I have two bikes with it, and the other one has recently started to creak when standing after a year and a half of trouble free riding.

PD2: plan B is a thread together BB. But a spacer is way cheaper and I happen to have a couple of shimano BB92 bottom brackets laying around.

Last edited by Amt0571; 06-25-20 at 03:56 AM.
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Old 06-25-20, 04:53 AM
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dsbrantjr
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My opinion is that the press fit BBs were not designed to be a superior solution, but a cheaper one to manufacture. I will stick with threaded, myself.
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Old 06-25-20, 05:55 AM
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Originally Posted by dsbrantjr View Post
My opinion is that the press fit BBs were not designed to be a superior solution, but a cheaper one to manufacture. I will stick with threaded, myself.
Agree, but that doesn't answer my question

I'd love to buy threaded BB bikes (and I do when I can choose), but unfortunately they are difficult to find. Even harder when you look for specific components on the bike you're buying or you have a limited budget.

I bought my first pressfit bike because I was looking for a road bike that had an aluminium frame, carbon fork, hydraulic discs, 11 speeds with 34-50 chainrings and was lighter than 9kg. When I found a new bike that met all the criteria for 1100€ and it's only downside was a pressfit BB, I had to pull the trigger. It was simply impossible to buy a comparable bike at that price with those specs, pressfit or not.
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Old 06-26-20, 08:30 AM
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