I've got an FSA MegaExo bottom bottom bracket that seems to have gone bad. I've head that FSA doesn't have the greatest bottom brackets, so I was going to try to replace it with this Shimano bottom bracket, unfortunately I've run into trouble. The bottom bracket tool I'm using seems to be a bit too big for the bottom bracket I have. When I apply force to remove the bottom bracket, the teeth of the tool dig into the bb's teeth and end up just deforming the teeth of the bottom bracket.

So my question: is there another way to remove a threaded bottom bracket, or do I need to buy a new tool? If the latter, do the bottom bracket tools come in different sizes? Which size should I buy?

I've posted a picture below in case it'd be of any help.

enter image description here

  • are you turning it the right way? The drive side cup is reverse threaded.
    – Kibbee
    Apr 16, 2016 at 22:13
  • Yeah, I'm turning in the opposite direction of the arrow. I'm starting to think it might just be a poorly manufactured bottom bracket tool. Apr 16, 2016 at 22:25

1 Answer 1


Park Tool list the BBT9 as the tool to use for both Shimano and FSA external bearing bottom brackets. I would see how tight the wrench fits on your new Shimano bearings. If the fit is as loose as on your FSA I would replace the tool so you don't strip the notches off your new bottom bracket. While the type of wrench with the open side allows tightening the bearing with the crank in place it is more prone to spreading than the type that forms a complete ring around the bearing.

  • Good point - I've never seen one that wasn't a big C shape.
    – Criggie
    Apr 17, 2016 at 6:41

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