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Cursed BB90 on its way out?

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Cursed BB90 on its way out?

Old 06-25-19, 04:52 PM
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road292
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Cursed BB90 on its way out?

If the article is to be believed, Trek is likely to ditch the much-hated BB90 in favor of the threaded T47.

I have too few posts to insert a link, bu the article is on the Cycling Tips website with the title "Trek rumored to be switching to T47 threaded bottom brackets"

Since all forms of press-fit BBs seem to be a royal PITA, this seems like a wise move.

Kinda-link: cyclingtips.com<SLASH>2019/05/trek-rumored-to-be-switching-to-t47-threaded-bottom-brackets/
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Old 06-25-19, 05:59 PM
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MEversbergII
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Link: https://cyclingtips.com/2019/05/trek...ttom-brackets/

I have no idea what that means (I know what those are, just not he significance) but I'm pretending to be helpful.
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Old 06-25-19, 06:12 PM
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Road 292,
It is likely a good move on their part. I remember the early Garry Fischer bikes with pressed in sealed bottom brackets and I got one with the wrong spindle. It went across the country twice before the customer got his bike. With a threaded BB I could have done it in an hour. Smiles, MH
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Old 06-25-19, 06:13 PM
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road292
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Thanks for the link fix. Working on my post count...

A few years ago Trek switched to a proprietary bottom bracket format they call BB90. They claimed it was awesome because it saved a few grams of weight by doing away with pretty much every part of the bottom bracket except the part that contains the bearings, which is pressed directly into the bottom bracket shell in the frame. The BB90 has been plagued by creaking issues, and the lack of bottom bracket support structure means the bottom bracket shell of the (carbon) frame slowly deforms or cracks. Trek's main motivation with BB90 seems to have been to save a few dollars and not a few grams. It's good (IMHO) that they seem to be considering moving back to a threaded design.
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Old 06-25-19, 06:32 PM
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My Domane had creaking issues since new in late 2017. Replaced the BB with a Token BB3724. Night and day difference. At my weight the difference in bottom bracket weight is negligible
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Old 06-25-19, 08:50 PM
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Originally Posted by road292 View Post
Thanks for the link fix. Working on my post count...

A few years ago Trek switched to a proprietary bottom bracket format they call BB90. They claimed it was awesome because it saved a few grams of weight by doing away with pretty much every part of the bottom bracket except the part that contains the bearings, which is pressed directly into the bottom bracket shell in the frame. The BB90 has been plagued by creaking issues, and the lack of bottom bracket support structure means the bottom bracket shell of the (carbon) frame slowly deforms or cracks. Trek's main motivation with BB90 seems to have been to save a few dollars and not a few grams. It's good (IMHO) that they seem to be considering moving back to a threaded design.
I'm no expert, but that sounds a lot like what my low-end Schwinn had - two ball races and a bit to connect the cranks. It creaked, shifted around a lot, and generally sucked.
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Old 06-25-19, 11:02 PM
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i have had external bb creak worse than my BB90 , hey what ever they choose as long as it add some performance to the frame ,
its definitely more user friendly ,
but you can still strip threads , crack your carbon bb shell area , and all sorts of other issues ,
no one system is a really better ,
external on alu frames are a good choice , but maybe when they switch we will see even more problems arise ,
with bikes its best to stick with what works ,
people have created all sorts of ways to make the problems of the bb90 easy to fix ,
simple solutions make these BBs easier to use , my tolken bb still creaks and makes wierd noises ,
but its smooth ,
and im really not worried too much
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Old 06-26-19, 08:07 AM
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Originally Posted by road292 View Post
Since all forms of press-fit BBs seem to be a royal PITA, this seems like a wise move.
Anecdotally, I would say some press fit standards do better than others. BB30, PF30 and BB90 are definitely perceived as problematic. BB86/BB92 and OSBB both seem to be more reliable. Note that Shimano, who is very conservative in their engineering, only supports BB86/BB92.

Also, there are certain manufacturers that seem to have fewer problems than others, likely due to differences in tolerances. Cannondale, Trek and Niner do not have good reputations while Giant, Look and Specialized are generally seen as less problematic. Of course there are exceptions.

I will say that of the 5 guys in my group who have either brand new or 1-2 year old Madones, 4 have had persistent BB reliability issues. Not a good sign, especially since these are very expensive bikes.

Last edited by Hiro11; 06-26-19 at 08:12 AM.
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Old 06-26-19, 08:47 AM
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road292
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Originally Posted by Hiro11 View Post
Note that Shimano, who is very conservative in their engineering, only supports BB86/BB92
If I understand correctly, the T47 supports the same 86.5mm bottom bracket shell width as the BB86 and BB90 (and maybe there also is a 92mm version for MTB; not sure). That seems to be one of its attractions, as it would require only minimal frame changes for manufacturers such as Trek that already have frames designed for 86.5mm bottom brackets.
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