Chain line adjustment

jammacdo
jammacdo Posts: 10
edited December 2010 in Workshop
Guys

I bought a track frame with the intention of using it with some road parts for a fixed wheel winter training bike.

I bought a new wheel with a fixed hub, however using the old Dura Ace 7700 chainset with a single 1/4" track chainring on the outside gives me a bad chain line. If I put it on the inside the chainline is ok but the chainring rubs the frame.

Should I?
1. Put a dent in the chainstay to allow the chainring to clear (its an alloy frame)
2. Get my LBS to swap the lock nut on the rear for a thinner one and pad out the left hand side by the same amount.

I'd rather not resort to bashing the frame but the chainring is touching by the narrowest of margins (the paint thickness!) so any dent would be marginal but I presume I'd have to clear a bit more to allow for frame flex.

Thanks

Comments

  • Steve2020
    Steve2020 Posts: 133
    I definitely wouldn't dent the frame except as absolute last resort. You might need more clearance than you think as the frame will flex will riding.

    Respacing the hub sounds better, but presumably will only work on its own if you can space it out to get good chainline with the ring in the outer position, which sounds like a long way? If you do that will the chain clear the seat stay?

    Could you use a smaller chainring (and a smaller sprocket obviously) to get more clearance?

    Use a BB with a longer axle and put spacers behind the sprocket?

    If you are very close you could maybe put a spacer under the fixed cup of the BB to move the whole thing out a notch? Sheldon Brown advises on this - I think you can use a Sturmey Archer sprocket spacer. In fact all of the above is probably just badly remembered stuff of Sheldon Brown's chainline article - you're probably better to read the organ grinder rather than the monkey!
  • jammacdo
    jammacdo Posts: 10
    Thanks, I'll lookup the article you are referring to and see about using those tricks. :D
  • jammacdo
    jammacdo Posts: 10
    Swapped the 48t chainring for a 42 and it clears. The 42 is a 3/32 and not a 1/8 but that should be ok for a road/roller fixie. Thanks for the advice, saved a lot of hassle. :D
  • Steve2020
    Steve2020 Posts: 133
    Glad it worked out. Looks like a late night at it!

Categories