Incorrect Chainline

Gazzaputt Posts: 3,227
edited May 2011 in Workshop
I built my new Canyon but I'm noticing the chainline in the top of the cassette (26 -21) are at such an angle that when in the top 26 at the back and 53 on the front the chain can drop to the inner 39 chainring.

I have installed the spacer that came with Mavic wheels and upfront I have a GXP BB which I think is 68-73mm.

I have adjusted the front mech and I can trim when I select the upper cogs and have no chain rub.

Any ideas?


  • keef66
    keef66 Posts: 13,123
    You'll get loads of people on in a minute telling you not to do the cross chaining thing, ie big to big.

    Out of curiosity can you measure the actual chainline? ie from the centre of the seat-tube to halfway between the chainrings?
  • Berk Bonebonce
    Berk Bonebonce Posts: 1,245
    Do you do lots of riding with your chain on the largest sprocket at the back, and the largest chainring at the front?
  • Bozman
    Bozman Posts: 2,518
    I ended up with a similar problem with a Viner, 25-21/53 gave me a hell of alot of noise, we all know about the rule but i'd never had this much crossover on any other bikes.
    Everyone seems to say chain alignment and "The rule" but i don't get this issue on my other bikes. Maybe it's an issue withe some frames/makers.
    I even swapped all of the equipment to my Look and that ran virtually noise free.
    You don't tend to use those ratios that often and the noise has died down a little with time but i'd put that down to chain wear which will end up shortening its life.
  • buder
    buder Posts: 154
    Interesting thread, Ive been wondering the same thing with my bike.

    Ive got a SRAM red FD and the only trim position is on the big ring. I can get a noise free operation in say 53/25 spinning along seated but out the saddle under heavy load from 21 onwards the noise is bad.

    Looking at the chain line its really bad I rang them when I first got the bike and said thats how it is nothing much you can do.

    For instance on 39/12 the chain is hitting the big ring the angle is that bad.

    I obviously dont use 39/12 and wouldnt even if I could but I do like to use 53/25 rather than change down and find 39/19 or something !

    I am not sure whats possible in the way of a solution !?
  • rubbernekker
    rubbernekker Posts: 112

    Have these bikes got very short chainstays? This is one factor - handles sharply but won't tolerate a crossed chain, and yes we all do from time to time.

    The only thing you can change in this instance is the distance from the chainrings to the centre of the seat tube.
    Are there any spacers between the BB cups on the drive side? Can you take them out or put them on the other side, or perhaps use a crush washer on the axle on the non drive side?
    GXP BB's have very wide cups and using a narrower BB may help.
  • Bozman
    Bozman Posts: 2,518
    There shouldn't have been any spacers/washers required, different makes of frame with roughly the same length chainstays. With my set up it was all new 10sp Duraace, chainset, BB, chain and cassette.
    I'm lucky that i was in a position to swap components over from one bike to another, i even swapped the wheels over but i still couldn't find an answer.