rustybuckets Reader
4/14/20 6:57 a.m.

Hi all, 

I'm hoping the forum's knowledge also spans across bikes, because I'm very confused right now.

I have a 2016 Trek Domane 2.0 Compact.

I love it - fast, fun, yada yada yada. 

However, as every trek seems to have this issue - I wore out the bottom bracket bearings late last year. I want to upgrade to something (open to suggestions on what! - I have 24mm cranks) that connects the bearings stronger than the plastic in my frame.

EVERYWHERE I look, the sites all say I have a BB90 bottom bracket, and everyone says the bearings press into the aluminum frame. Cool, EXCEPT, that is not what I found at all when I took the bearings out.

The bearings actually press into plastic cups.

And, the bottom bracket dimensions are shown below;


FROM WHAT THE INTERNET SAYS - this matches bb86 dimensions. I had originally ordered this guy below, but it would not fit the plastic cups or my frame:


So, what non-OEM assembly can I buy that is compatible and will give me a longer service life and better performance?

Any help would be super appreciated! Thanks!


adam525i (Forum Supporter)
adam525i (Forum Supporter) HalfDork
4/14/20 8:06 a.m.

You are right that based on your dimensions you need a BB86 which is a good thing as it should open up more options than the Trek only BB90 standard. This Park Tools page gives a good run down of the various standard but you've probably already figured that out.

This is probably the style of BB you are looking for but that price is on the higher side -  Wheels Manufacturing BB86, it looks like it also requires special wrenches for installation. You can just replace the sealed bearing down the road which is nice. Otherwise I'd just keep buying cheaper plastic based bottom brackets and putting a bit of grease on all of the mating surfaces to keep it quiet (I'd probably do that on the Wheels one as wheel).



TJL HalfDork
4/14/20 8:15 a.m.

They use a plastic cup for the BB? That sound like a terrible idea. Is there some advantage to it that im not thinking of? Even super cheap bikes with a euro bb that ive had were threaded. 

rustybuckets Reader
4/14/20 8:34 a.m.

In reply to adam525i (Forum Supporter) :

Thank you! Confirms that I am at least headed down the right path. And I really like that BB you linked. I jumped the gun earlier today and ordered this guy since it comes with the tool (also prime so free shipping/returns lol), but I had not seen the Wheels Manufacturing one yet either:

Thanks again!

rustybuckets Reader
4/14/20 8:48 a.m.

In reply to TJL :

I believe it's because the plastic allows for frame manufacturing variances, i.e. they can run looser tolerances on the frame and when pressing in the plastic cups and metal bearings, the plastic cups will give, not the frame or bearings. It sure doesn't add any rigidity to the structure, however, and even at 165lbs, when I'm out of the seat and cranking hard on the pedals, it ends up with a lot of stress on one bearing surface, not split across both. So hopefully the token one works by tying the cups together!

fatallightning Reader
4/14/20 4:21 p.m.

Yep, BB86. Scott and BMC also use them.  I work in a shop and honestly haven't seen much premature wear as compared to say BB30 in Cannondales or BBRight in Cervelos. If you got 2 years out of it, I'd just buy another Shimano one for $35.  The idea is the plastic cups have just enough deformity to take up some of the manufacturing variance. You're also not wearing the bearing mounting surface with repeated install like you would when you have a metal bearing being pressed right into a metal shell. In the gram war, manufacturers also looked to get rid of the metal bottom bearing insert for both weight and simplifying manufacturing. 

I'm curious how that Token one you ordered fits both BB86/BB90 and BB30/PF30, which are all different ODs. Must use those Delrin step down adapters pressed into the frame, then the assembly mounts into that.

rustybuckets Reader
4/15/20 7:23 a.m.

In reply to fatallightning :

Correct- the Delrin spacers take up the differences  

install went smooth, torqued to spec easy. Still getting a "pop" every few rotations  I suspect that I need to use loctite bearing compound on the crank to bearing surface, as when I spin the cranks by hand it glides very well, but when under load, I get the pop.  I think the crank is slipping in the bearing race, but we shall see later today! 


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