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Octalink BB sizing

bluehelmetbluehelmet Posts: 156
edited February 2010 in MTB workshop & tech
Hi all

My BB has finally packed in after 2 years. It's an Shimano Octalink jobby on my '08 Spesh FSRxc.

Not wanting to waste any time I looked on the Specialized website and the specs stated it as 68x118 so I ordered that a few days ago. Got round to taking out the old one last night and it says 68x121 on the body of the BB. Aaaaarrrgh! :evil:
I also noticed there was a shim between the frame and the cup thread head on the drive side that was a few mm thick.

Basically is 3mm difference in length going to make that big a difference to my chain lines (is it 1.5mm each side or 3mm of the drive side?).

Any advice welcome.

Posts

  • nicklousenicklouse Posts: 81,520 Lives Here
    so the old one has an E in the part number.

    and i would be getting another BB.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • supersonicsupersonic Posts: 82,708 Lives Here
    I'd get exactly what was in there. The 121 for some reason are usually cheaper too!

    http://www.chainreactioncycles.com/Mode ... odelID=908

    10 quid, job done!
  • supersonicsupersonic Posts: 82,708 Lives Here
    Just to clarify that, same size wise.

    Don't use the spacer this time.
  • Cheers SS & Nick.

    That's what I thought myself and that's the exact one I was looking at last night, was just hoping to get out and ride this weekend by using the 118.

    SS: Why not use the spacer when I'm replacing it with the same sizes?

    Right, time to see how good are CRC returns are...
  • supersonicsupersonic Posts: 82,708 Lives Here
    It sounds like your existing bottom bracket was an E type - it needs the spacer (usually a BB mounted mech would fit there). Normal ones do not need the spacer.

    The 118 may work - but I remember very well what happend when I put a 118 in my Zaskar frame when 121 was specified for the correct chanline - the inner chainring tabs fouled the frame!
  • Oh yeah. Good point, well made.

    Think I'll not risk it and get another one. More days off the bike... :(
  • konadawgkonadawg Posts: 447
    Happened to wonder about that a couple of days ago, seeing as CRC had some deals on 118mm BBs but not 121...

    Could it be a question of checking the clearance? Some frames may have more than plenty chainring clearance, and 3mm is not that much?

    What's the final word on this Nick?
    Giant Reign X1
  • supersonicsupersonic Posts: 82,708 Lives Here
    If in doubt, replace with the same or measure ;-)
  • Okay,

    So i got one of the BBs that S'sonic has a link to from CRC as a replacement. Went to fit it last night and I can't get the plastic sleeve on the non-drive side to screw all the way in - it ends up with about 2mm of thread still exposed.

    I've tried it without the BB in place and it does go all the way in so the only thing stopping it is the BB shell. I've had all my (considerable) weight on my wrench and it just won't go in all the way.

    Any ideas?
  • nicklousenicklouse Posts: 81,520 Lives Here
    edited February 2010
    sounds normal.

    but just to be sure back the BB out from the drive side a bit and then tighten the ND cup and then go back to the D side.

    the Drive side face could be out and moving the BB in the BB shell .
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Cheers nicklouse,

    Just wanted to check.

    Woo, I cab get back on my bike! :D
  • nicklousenicklouse Posts: 81,520 Lives Here
    just see the edit above. as some should be snug.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Ta, will check later...
  • Dirtydog11Dirtydog11 Posts: 1,621
    bluehelmet wrote:
    Ta, will check later...

    Just to clarify guys. I have fitted two of those ES51 BB to my other bike and can confirm that the plastic cap (non drive side) doesn't screw all the way in , I too have a 2mm gap or thereabouts.
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