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I'm planning on replacing a Shimano FC-510 crankset with an FC-R7000. The bottom bracket has had light use (~2000km) and has no obvious play in it, however the videos I've seen showing removal of these types of cranksets suggest I might need to use a soft mallet to get the axle out. Could the crankset removal process damage the BB bearings, and should I have a replacement BB on hand?

Thanks

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No, the process of removing the drive side crank and axle by tapping with a soft-faced mallet will not harm the balls or races in the bearings. The balls and races are hardened and the axle is not a true 'interference' fit in the inner races so you don't have to tap the axle very hard to get it to move.

You can review the Park Tool Repair Help page on two-piece crank removal. If there was a danger of damaging the bearings it would be mentioned and steps to avoid it described.

I will note that I have encountered a FSA PF30 crank that was really tight in a SRAM BB, but you should not have that problem with Shimano cranks in high quality BB bearings.

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  • I can verify the tight fit. I thought I'd done something wrong when I did just this pairing. I ended up using a block of wood with a mallet and lots of time and patience. It rolls perfectly well, just a tight fit. – Andrew Oct 5 '20 at 20:29
  • @Andrew, I had the same problem with FSA bearings so very likely the FSA crank is at fault – Argenti Apparatus Oct 5 '20 at 20:35
  • Do you mean that you currently have an FC-5100 crankset which needs to come out? FC-510 (properly, FC-M510) intimates an older Deore MTB crankset that uses either square taper BB's (early versions of the 510) or Octalink BB's in later versions. I suspect a typo. Hollowtech2 cranksets do require a bit of persuasion after the bearings have been preloaded and a little more so after being ridden in my experience. – Jeff Oct 6 '20 at 5:29
  • @Jeff I think op has R5** ‘non series’ crank, those are HT 3 piece but are heavy, you get em in bikes where manufacturer is cutting costs – Argenti Apparatus Oct 6 '20 at 13:44

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