Press fit bottom brackets. Why not just change the bearings rather than the cups aswell?

shimanobottombracket
shimanobottombracket Posts: 376
in Workshop
Rather than having to smash out the whole unit, is it feasible to extract the cartridge bearing and just replace that? Why not?

Comments

  • masjer
    masjer Posts: 2,655
    You can but the cost of two good quality bearings will likely be more expensive than the whole Shimano BB. The size of the bearings (25x37x6) are a non-standard size, so you'd have to buy cycle specific bearings -which can be more expensive. Also it's easier to remove the whole BB than to extract the bearings without damaging the plastic top-cap and seal.
    Planet X have Shimano BB at £10 - 20% at the mo!
  • thecycleclinic
    thecycleclinic Posts: 395
    edited March 2020
    25x37x6mm are not really available anyway. Some bb allow you to change the bearings. It normally the more expensive one with better bearing to start with. Shimano press fit bbs are pony. Never had one that lasts compared to campagnolo.power torque or a good old square taper bb.
    www.thecycleclinic.co.uk
  • david37
    david37 Posts: 1,313
    Depends which bottom bracket you have. The pf30 standard for example is designed to be replaced as a whole, i.e. cups and bearings. Specialized were at one point (and may still be for all i know) advising dealers to bond the cups in place to try and eradicate creaking!

    Functionally that's getting very close to the point that the frame life is tied to the bearing. Banging out those bearings leaves out of shape cup and it's all down hill from there. The amount of force (heavy duty abuse with ever larger hammers) required to move some cups is epic!

    Like cycleclinic says, some BBs allow you to replace bearings by pressing them out. eg wheels mfring but they recommend using a press to press them out rather than time honoured hammer and punch. the bearing removal components come as a kit for c £100........

    the shimano screw in bbs as other have said can be had for less than the cost of a single decent bearing. Probably an indication that theyre not going to last for ever. having said that my winter bike hs had a dura ace one which you can have for a bout £20 if you shop around. its been in for 5 years and is perfectly fine.

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