Bottom Bracket

Hi all,

Got some issues with my bottom bracket at the moment and in need of an overhaul, I have a press fit bottom bracket and am struggling to identify exactly what make / brand I should be looking at. Upon searching for a "press fit" bottom bracket I can't seem to get any results. I'm running 105 running gear on an Avanti Quantam. Can anyone help?

How do you mean "press fit." Are the bearings installed by themselves in the bike's bottom bracket shell, or are the bearings in "cups" that are screwed into the bottom bracket shell?

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Older 105 would have an Octalink bottom bracket; newer would have external cups. In either event, BB is not "press fit". The BB instead screws into threads in the frame's bottom bracket fitting.Note that threads on the right (drive) side are left-hand (reverse) threaded. Refer to the Park Tool website to determine what removal tool(s) are appropriate to your situation.
Park Tool Website

You might also benefit from a look at Sheldon Brown's (RIP) website:
Sheldon Brown's Bicycle Glossary Bo--Bz

Here's a link to an Octalink BB photo:
File:Shimano-octalink.jpg - Wikipedia, the free encyclopedia

Since you haven't been very specific, let me generalize by saying you should replace like-with-like ...

If the crank is Campagnolo, for example, you would get a Campagnolo BB which is appropriate to the particular crankset.

If the crank is Shimano, then you should get a Shimano BB for the particular vintage of crankset. Because you are so vague in your description, here's a good instance of following the marketing department's suggestion that you match a 105 BB with a 105 crank, an Ultegra BB with an Ultegra crank, etc. to avoid getting the wrong BB.

In other words, identify the crankset, and then buy an appropriate BB + tool(s) OR bring your bike to your LBS.

If you have an FSA MegaExo crankset, then you should probably consider getting a Shimano Hollowtech II BB as a direct replacement ... the Shimano Hollowtech II BB supposedly has better (longer lasting) bearings than the FSA MegaExo BB (I don't know if that's true, or not).

You CAN theoretically remove the plastic cover which shrouds the bearing, then READ the specific information molded onto the cartridge bearing's plastic cover, and buy the appropriate replacement bearings ...

OR, consider buying a new BB & crank combination if you happen to have an older, square taper BB (not that there is anything wrong with that design).

To follow up on my earlier response, is it possible that you've gotten your hands on one of Shimano's new threadless/press fit bottom brackets like the one described in the link below?

Shimano's Secret Bottom Bracket Cartridge

Given that they're new and not widely used (to date), it seems unlikely. But if your bike is new since late 2008, then possible. As the article (dated 8/27/2008) says, "Don’t expect to see Shimano’s threadless bottom brackets in the glass case at your local dealer for a while, but watch for them on elite-level mountain bikes as the season progresses"