New BB & cranks... recommendations needed

Discussion in 'Mountain Bikes' started by Harry Asperger, Aug 1, 2007.

  1. Harry Asperger

    Harry Asperger New Member

    Aug 1, 2007
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    I have a nice light MTB, that has had an old Alivio BB & cranks on it for ages. I always meant to upgrade, and well... The bike is really good quality, and I think deserves better (and lighter) components.

    So now the BB is worn out, and I need a replacement. It is square drive, and I'm tempted to get something stronger and more up to date. I like the idea of the HollowTech LX & XT cranks, but I'm not so keen on proprietary systems. So maybe ISIS is the way to go.

    Also, the bike is 7 speed at the moment. Would I be wise to upgrade to 8 or 9 speed at the same time as changing out the cranks & BB?

    So, please give me a little guidance. I haven't looked at this stuff for ages, and it seems mind bogglingly complex to me at the moment. :)

  2. alfeng

    alfeng Well-Known Member

    Jul 23, 2005
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    FWIW. I would avoid ISIS ... it was an "okay" idea whose time has come-and-gone. ISIS was afflicted with uneven (the nicest way I can say it) BB quality.

    In the long run, I think that you will be happier with the SHIMANO Octalink (still available, I think) OR one of the newer cranks which use the external BB OR with another square-taper BB & crank (about 1/3rd of my bikes have square-taper cranks).

    The Shimano & FSA external BBs are interchangeable ... it is the new "standard" for external BBs (no offense to Campagnolo & GXP).

    BTW. You could just get a new, square taper BB (e.g., SHIMANO UN-51, UN-71, UN-91) and/or chainrings for your current crank.

    But, if your bike has a cartridge BB, for the time being, with the bike on its side, put a few drops of 3-in-1/household oil in the BB where the spinde exists the BB. Wait. Put your bike on the other side & repeat. You may be pleasantly surprised at what a little "regular" oil will do for some bike components.

    If the bike's current BB has loose bearings, you could just repack the bearings.

    I think that unless your shifters are shot, you are probably better off staying with 7-speed for the time being.