Bottom Bracket and CrankSet Confusion

cdubu
cdubu Posts: 26
edited October 2009 in MTB workshop & tech
Hi all,

I need to replace the crankset on my Mongoose Teocali and I am getting really confused so I hope someone can help...

I believe the BB is a Truvativ / SRAM GXP External Bearing type.
What I need to know is, am I limited to only Truvativ and SRAM GXP cranks iwith this bottom bracket or can I use another make?

If the selection is limited is it worth replacing the BB for something more usual like a splined bb?

Last question but probably the stupidest:
I have some perfectly good bottom brackets kicking around, are all MTB bottom brackets the same size and therefore could I use one of these:
Shimano BB from a Nirve
ISIS from a Coyote

Thanks in advance, be gentle!

Chris

Comments

  • bomberesque
    bomberesque Posts: 1,701
    Last question first; BBs spindles vary in length as do BB shells. Spindle length is dictated by the crankset, Shell length by the frame so the BB needs to match both of these (although most new BBs will fit any shell size with spacers, many older ones won't)


    As for your current crankset, the BB is integrated with the crank on external bearing types so don't worry. Get a new crank if you want (Shim Deore is a very good value option) and you will get the BB included. The spindle itself is bonded to one crank and the bearing cups screw into the frame separately. You need some specific tools to remove and fit them though.
    Everything in moderation ... except beer
    Beer in moderation ... is a waste of beer

    If riding an XC race bike is like touching the trail,
    then riding a rigid singlespeed is like licking it
    ... or being punched by it, depending on the day
  • nicklouse
    nicklouse Posts: 50,673
    cdubu wrote:
    Hi all,

    I need to replace the crankset on my Mongoose Teocali and I am getting really confused so I hope someone can help...

    I believe the BB is a Truvativ / SRAM GXP External Bearing type.
    What I need to know is, am I limited to only Truvativ and SRAM GXP cranks iwith this bottom bracket or can I use another make?

    If the selection is limited is it worth replacing the BB for something more usual like a splined bb?

    Last question but probably the stupidest:
    I have some perfectly good bottom brackets kicking around, are all MTB bottom brackets the same size and therefore could I use one of these:
    Shimano BB from a Nirve
    ISIS from a Coyote

    Thanks in advance, be gentle!

    Chris

    your crankset is not compatible with your old BBs as they are a different system.

    Read parktools for more info on the BB types.

    Yes you are limited to the GPX type BB cups as the non drive side bearing is smaller than the drive side. So makers do a shim for this like Hope).
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • cdubu
    cdubu Posts: 26
    Thanks for your help guys.

    I checked out the Park Tools guide, very helpful. Thanks. I can't believe how complicated BB's are these days! Back a few years it was ISIS or Square Taper, easy!

    I have taken the easy option by keeping the BB (it aint broke...) and found a reasonable chainset to fit: http://www.chainreactioncycles.com/Mode ... elID=23241

    Thanks for the advice on the shim. So I guess if my BB fails in the future I can use these: http://www.chainreactioncycles.com/Mode ... elID=26899 and get a HOPE BB.

    Thanks so much...

    C.
  • bomberesque
    bomberesque Posts: 1,701
    you will get a new set of BB bearing cups with that chainset. Just keep them. When/if your current ones wear out you just swap in the new one.
    Everything in moderation ... except beer
    Beer in moderation ... is a waste of beer

    If riding an XC race bike is like touching the trail,
    then riding a rigid singlespeed is like licking it
    ... or being punched by it, depending on the day
  • cdubu
    cdubu Posts: 26
    It comes with the BB cups too!

    A chainset and BB for £32! That is a bargain,

    Thanks for your help today guys...

    C.