Chainline info (fixed gear conversion)

pete_s
pete_s Posts: 213
edited December 2012 in Workshop
Hi! I couldn't be more confused and am hoping somone can help me out with a chainline question.

I'm converting an old frame which was originally a 10 speed road bike to a fixed gear one. I just can't get my head around the idea of matching bottom brackets to cranks to hubs.

How do you determine what cranks and bottom bracket I need to use if the hub I want to buy has a chainline of 42mm?

Thanks for any advice and knowledge.

Pete

Comments

  • Monty Dog
    Monty Dog Posts: 20,614
    http://sheldonbrown.com/chainline.html

    Your inner chainring position is 41mm which should be sufficient for your 42mm hub - problems arise when you are more than 3-4mm out
    Make mine an Italian, with Campagnolo on the side..
  • pete_s
    pete_s Posts: 213
    Cheers Monty.

    I'm beginning to understand it now and I've found a database of what components have been known to fit together.

    In your experiance what do you when setting up a chain line? Do you match the hub to the cranks or the cranks to the hub?

    Pete
  • Monty Dog
    Monty Dog Posts: 20,614
    You can sometimes adjust chainline slightly if the rear sprocket has a shoulder and you can screw it on the other way around. Adjusting the chainline is more problematic at the chainring end, particularly with external BB cranks as you have no real means of adjustment, but you can put shims (thin washers) between the ring and crank spider to move the ring inboard if on the inside. As long as you minimise slack in the chain and keep chainline within a mm or so, I've never had any problems.
    Make mine an Italian, with Campagnolo on the side..
  • FatTed
    FatTed Posts: 1,205
    This hub has a chain line of 41 mm (or46)
    Ready Converted Shimano XT M756 Hub

    http://www.velosolo.co.uk/shophub.html
  • pete_s
    pete_s Posts: 213
    Yeh, I've seen those FatTed and I'm going to get one as I think it's the easiest way for the frame I've got. It also opens up more opportunity to get some nice vintage cranks. Seen some Dura-ace ones, but can't find an appropriate bottom bracket for it. I belive it needs a 112mm one, but can find any. Would a 111mm one work with a 1mm spacer?

    Cheers
    Pete
  • FatTed
    FatTed Posts: 1,205
    I have FSA Gimondi Singlespeed Chainset with the square taper BB they recommend gives a perfect chainline
    I think I ended up with a 46mm chainline
    see the FAQs on velosolo site