Bottom bracket friction

normanp
normanp Posts: 279
edited November 2007 in Workshop
Has anyone done a comparative study of the friction in BB bearings? My Campag taper Record BB is a dream - silky smooth and practically frictionless - I can really feel the difference between this and a Shimano Ultegra octalink on another bike (BB replaced a few 100 kms ago). Are newer BB setups any better? I wonder if the bigger bearings in Campag Ultra-torque or Shimano Hollowtech 2 have more or less? I also wonder if a BB shell which is badly machined could cause friction as the sealed bearing unit is stressed by it.

Comments

  • e999sam
    e999sam Posts: 426
    I've just fitted a Hollowtech 2 and I don't think it is much different from the Octalink that it replaced. I don't think either run as freely as the Campag and stonglight BB I used in the 1980's.
  • grahamspankee
    grahamspankee Posts: 2
    If you don't mind the slight hijack: I've just installed a new Chorus BB in my (new) frame, and I'm surprised to find that the cranks, unencumbered by chain, will only do a couple of revolutions if I set them spinning with a firm push of the hand. Surely they should just spin and spin?

    I've had the shell tapped and faced. There's no graunching noise or anything. The only thing I can think is that I haven't yet put any extra grease in the bearing cups, as there was a reasonable amount on the bearings and cups anyway. Any ideas?
  • John.T
    John.T Posts: 3,698
    The drag is from the seals. It will get less as they bed in.
    My Fleet.
  • aracer
    aracer Posts: 1,649
    You're worrying about drag which makes no perceptible difference in reality. As long as they're smooth it doesn't really matter.
  • grahamspankee
    grahamspankee Posts: 2
    Marvellous, thanks both for putting my mind at rest.

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