Hi, working on my roadbike for the first time and wanted to clean everything when I found this part that probally doesnt look like what its suposed to look like any more.
Wondering if there is a direct cause to this or its just worn
by UnicornPissParty
7 Comments
The middle plastic part is optional, if the bearings are good you can still use the BB without.
Looks like a too wide BB in a too narrow BB shell. MTB BB in a road bike? Read this:
<https://www.tobiasfeltus.com/blog/the-burning-question-can-i-use-a-shimano-road-bottom-bracket-on-a-mtb/>
I can only think that it was misaligned when threading in the second BB cup, which caused it to catch one side and push it back like that. It’s not that it was too long or it would be crushed evenly.
Although you can run it without this I wouldn’t recommend it as moisture and debris always make their way inside the frame and leaving this out would shorten your BB lifespan.
This is MTB specific BB.
You need something like BB-RS501
The BB Cup says “Mountain” on it, which means that the sleeve was too long for a road bike, and the person who installed it just forced it and it got compressed. The two fixes are to either throw the sleeve away and run without it (you lose water sealing doing this, but it’s not a huge deal), or buy a proper Road sized BB (Shimano ones like the SM-BBR60 are really cheap, $20-35, and high quality).
Probably just slightly misaligned when fitting. That plastic piece isn’t needed anyway.
That’s a MTB BB you need a road bike BB. The BB shells are different sizes. It’s clearly been forced and twisted in against the bearing