Bottom bracket confusion?!?!?!?!?!?

MarkEo
MarkEo Posts: 308
edited July 2009 in MTB beginners
Hello, im building a mtb bike from scratch and iv been looking at bottom brackets, i know i need a 68mm bb but i have noticed other measurments along side the 68mm measurment (im guessing this other measurment is the length maybe?) If im right can anyone tell me how i work out the right length bb for my bike? or what the other measurment is if im wrong? Thanks, markEo
Tis better to regret something you've done than to regret not doing something!

Comments

  • nicklouse
    nicklouse Posts: 50,675
    well it all depends on what cranks you buy.

    just get some Deore HT2 get the bb shell faced and there is nothing to think about as it is all included and fits.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • MarkEo
    MarkEo Posts: 308
    Ah well i already have a crank and im a bit short of money but i want to get my bike up and running for summer, all i need is a bottom bracket which iv found but theres a few different measurments which confused me a bit, i dont wanna buy one that doesnt fit thats all, thanks anyway, does any one else know the answer?????
    Tis better to regret something you've done than to regret not doing something!
  • nicklouse
    nicklouse Posts: 50,675
    so then what are the cranks you have?

    make, model, year and part number.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • MarkEo
    MarkEo Posts: 308
    Its a Truvativ Comp G crank, not sure of the year or part number though, will it be on the crank? (sorry im sounding a bit usless, iv only just got back into mtb again after a few years off) cheers
    Tis better to regret something you've done than to regret not doing something!
  • nicklouse
    nicklouse Posts: 50,675
    so it is the ISIS fitting?

    a 113mm ISIS bb is what you need.

    most come with spacers to fit both 68 and 73mm bbs.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • MarkEo
    MarkEo Posts: 308
    ISIS? Does that mean square tapered?
    I definately know its 68mm and thanks, i was looking at the 113mm one to start with so i was sort of right haha
    Tis better to regret something you've done than to regret not doing something!
  • nicklouse
    nicklouse Posts: 50,675
    No Square taper is Square taper.

    ISIS is one splined standard.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • MarkEo
    MarkEo Posts: 308
    One splined standard? sorry you've lost me?
    (you can just ignore me if im irritating you, sorry)
    Tis better to regret something you've done than to regret not doing something!
  • nicklouse
    nicklouse Posts: 50,675
    ok rephrase that One of the splined standards.

    there being

    ISIS.
    OCTALINK.
    Powerspline.
    Howitzer.

    and then from the BMX world the 36 and 48 spline fittings.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • junglist_matty
    junglist_matty Posts: 1,731
    edited July 2009
    If its these cranks...
    http://www.chainreactioncycles.com/Mode ... elID=24648

    You need one of these bottom brackets:
    http://www.chainreactioncycles.com/Mode ... elID=17720

    113mm is the spindle length
    68mm is the shell length
  • MarkEo
    MarkEo Posts: 308
    ah right, and how do i know which one iv got? or was that what you told me before?
    Tis better to regret something you've done than to regret not doing something!
  • nicklouse
    nicklouse Posts: 50,675
    well is it is not square taper it could be ISIS or Powerspline.

    normally written on the arms.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • junglist_matty
    junglist_matty Posts: 1,731
    MarkEo wrote:
    ah right, and how do i know which one iv got? or was that what you told me before?

    Uh, because of your cranks!!!!

    Think about it, you have a hole at the end of your cranks (where the crank goes on the Bottom Bracket), you need to match that hole up with the BB, its like a jigsaw, get the wrong BB or the wrong crank and they won't fit together!

    ISIS cranks means ISIS bottom bracket, your cranks are ISIS, its not that difficult to understand!!!

    Read this...
    http://en.wikipedia.org/wiki/Bottom_bracket
  • junglist_matty
    junglist_matty Posts: 1,731
    nicklouse wrote:
    well is it is not square taper it could be ISIS or Powerspline.

    normally written on the arms.

    Yeah, the cranks he's got are ISIS, it says it on the crank arm.
  • MarkEo
    MarkEo Posts: 308
    Ah, my cranks dont say ISIS on it like the one on the link, its a square taper, which i did already know, all i was trying to find out was what length bb i need but i think i know that now thanks very muchly to the both of you for the help and sorry for the stress haha
    Tis better to regret something you've done than to regret not doing something!
  • woodywmb
    woodywmb Posts: 669
    nicklouse:
    It's one of those combination BBs, Isis at one side and square taper at the other. You need to buy two cranksets to find a match though. :lol:
    http://www.pinkbike.com/photo/1296598/
  • MarkEo
    MarkEo Posts: 308
    Nope wrong again, theres a square hole at the top of each arm and no ISIS written anywhere
    Tis better to regret something you've done than to regret not doing something!

Categories