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I have a Specialized Tarmac Comp bike from 2010. It has a Shimano 105 SM-FC5600 Bottom Bracket that I want to replace. It makes clicking sounds, after 50.000km of use. I think I can use any shimano bracket set for Hollow tech II, I currently have a Shimano Ultegra crank set on the bike with the 105 bracket.

The problem is that a bracket comes with either BSA thread or Italian thread. I can't find online what thread my bike has. I emailed Specialized, I expect a reply i a few days. I wonder, is there a way to find out what thread the frame of my bike has?

Edit: On the bracket is stamped "1.37x24" I found that this means it has BSA thread. Problem solved, unless someone has additional tips :-)

Edit 2: the diameter of the 105 bracket bearing is 44mm, a new one has 39mm, so I need two different bracket grips.

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As I discuss in this answer, only some Italian bikes use Italian threaded bottom brackets. Most of the time, a frame with a threaded BB will use BSA (very common even though it’s an older standard) or T47 (less common, newer standard, possibly growing in popularity).

To replace a BB, you do need to know the shell type and your crank spindle type. You said you have a Shimano Ultegra crank, which I assume is from the same era as the 5600 groupset (I.e. probably the late 2000s or early 2010s). You can actually replace the BB with any Shimano Hollowtech II BB. You aren’t likely to go wrong with a different Shimano unit. If you went looking for third party BBs, you want to search for “BSA” and “Shimano” or “24mm spindle” - because Shimano crank spindles are 24mm in diameter.

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  • Actually, the Ultegra crank set is recent, I bought it from Stages, with a power meter built in. But you're right, if it's hollowtech II, it will fit.
    – Christine
    Jul 1, 2022 at 11:14

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