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Bottom Bracket Compatibility

Hi folks,

I bought a bike with a Tiagra Groupset, and a pressed fit bottom bracket in 2021 - a Cube Attain Race.

I was thinking about upgrading her to 105 as a winter project - buying parts off a damaged bike or similar. The bit that is troubling me is bottom bracket compatibility - there seems to be a million different standards.

If the bottom bracket of the bike I am purchasing them from is not a pressed fit, it is a BSA or something else, am I likely to end up with a crank-set that doesn't fit my bike.

Ray K

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    lesfirthlesfirth Posts: 1,383
    No problem. A 105 crankset will be a straight swop for your Tiagra. No need to change the bottom bracket.
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    As above Ray, no issue. The reason being both the Shimano cranks have a 24mm spindle diameter so the BB already fitted will be specific to Shimano cranks. You are right, it is a minefield though!

    As an aside, if you are upgrading to 105, you can buy new parts and full groupsets for pretty good prices now. A full 105 rim brake groupset will come in at around £400 which is probably the best value value on the market nowadays.
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