Weight Weenies

hi all,

cleaned the bike today and realised the bb30 bottom bracket on my caad10 has developed some play. By this I mean by holding one crank arm I can slide the entire bottom bracket roughly 1mm in and out of the bb shell.

Now only 2 weeks ago my mechanic at the lbs replaced the bearings and regreased everything in there and since then I have only ridden this bike twice. My thinking is that he didn't install the bottom bracket correctly and over these 2 rides its simply loosened up?

I consider myself pretty good at servicing everything else on the bike just don't have the funds (student) to invest in tools to checkout the bb.

What are your thoughts?

sounds like incorrect install

generically it could be...
- preload adjuster hasn't been set (if it has one, some just have a stack of washers in which maybe they're missing)
- spacers or bearing covers are missing
- the two parts of the crankset haven't been fully scrunched together by the locking bolt

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edited

This is a picky point but wave washers should be complety compressed. If you do that you are putting un do sideload on the bearing. You might as well just use a shim thats the same thickness as the wave washer. Just make sure that the wavewasher is lightly compressed.

I deally, if you like to tinker and have very thin shims, you would not use a wave washer and just use shims that allow no slop but just barely sideload the bearing.

This is a picky point but wave washers should NOT be completely compressed.

That's what you meant to say, right?

From Cannondale:

Apply bearing grease to the crankarm BB spline hole, spindle end
and the thin washer and fixing bolt threads. Tighten-non drive the
fixing bolt to 40 Nm, (30 FtLbs) and check to see if wave washer
is properly preloaded (still has slight wave and not loose). If it is
loose, remove the crankarm and add another shim. Up to 3 shims
can be used. Add shims as needed.

BB30 design is a sore point for me too.
Notice that SRAM has gone back to an adjuster that takes out all the play without a wave washer.
I believe the wave washer is a bad design. You should use shims that take up all the space, but do not put a significant sideload on the bearings.
I had a lot of creaking and clicking problems until I used some feeler gages to add just enough shims to where the wave washer is just crushed flat, but no further. That seems to work for me.

Yet another reason threaded bottom brackets rule!

If it ain't broke don't fix it.

Best way to adjust preload on a wave washer system:
First install everything with no additional preload spacers. Check the amount of space is in the "wave" part of the wave washer. Physically slip a number of preload spacers in that gap, the number of spacers that EASILY fits is the number you use. It is allowed to compress the wave washer all it wants as long as it does not bottom out. A tiny gap is still a gap.

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