Chain line

simbil
simbil Posts: 13
edited January 2010 in MTB workshop & tech
I'm running a single chainring up front and 9 at the back. The bike came as a double unusually, and the chain line from the inner chainring (the only one I am running now) lines up with number 7 on the back. That means that the chainline to the big rear cogs, especially number 1, is quite bad. I've had a snapped chain and lots of chain falling off I think as a result of this.

My question is, I guess it would be ok to add some washers to change the chainline a bit? Does anyone know a good online spot where I could get the necessary bolts and spacers?

The bolts the bike came with are plastic and I would like to replace them anyway.

Thanks :)

Comments

  • nicklouse
    nicklouse Posts: 50,675
    a double?

    which positions?

    what is the bike? what is the crankset? and year?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • simbil
    simbil Posts: 13
    It's a bike I bought second hand and It is built around a Niner frame - it's not an off the shelf spec. It's a couple of years old I think, certainly not more than 5.

    The chainset is a Cannondale double, the inner ring is the one I use and it's 29T.
  • nicklouse
    nicklouse Posts: 50,675
    what fitting if the crankset?

    pics?

    more info needed what length axle etc etc
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • simbil
    simbil Posts: 13
    Sure, I'll take some pics tomorrow.
  • simbil
    simbil Posts: 13
    Looks like it might be a cyclocross chainset - Cannondale CX2 I think...

    http://www.flickr.com/photos/16711665@N07/4313363693/in/photostream/

    http://www.flickr.com/photos/16711665@N07/4313365859/
  • nicklouse
    nicklouse Posts: 50,675
    any idea if it is a squretaper fitting or octalink or ISIS?

    and do you know the axle length?

    and it does not look like you have much clearance from the rings to the chain stays.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • simbil
    simbil Posts: 13
    Could not get the cranks arms off to check it out properly.

    There is about 7mm clearance between the ring and the frame.

    I measured from the outside of each crank arm and it is 140mm. Not sure if the axle length can be guessed from that?
  • nicklouse
    nicklouse Posts: 50,675
    to get the arms off just undo the bolt as it is a self extracting one that is fitted.

    your only real option is a new bb with a shorter axle.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • simbil
    simbil Posts: 13
    To undo the crank arms, I tried to undo the 8mm hex bolts but they would not shift. Are you saying I should try something else - not sure what you meant.

    I'll have a look at the axle if I finally get the thing off!

    I take it you are not keen on putting washers between the spider and the chainring?

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