Fixie hack - chain issues

craker
craker Posts: 1,739
edited December 2011 in The workshop
I turned my 14 speed Raleigh into a single speed commuter - for the most part I love riding it like this. It's got semi-horizontal dropouts so I've shortened the chain to suit the 17 tooth gear on the cassette.

Getting the chain tension right seems tricky. Last week the bike developed a habit of jumping onto the next gear down (15) and then off. This morning it went the other way onto the next gear up. The chain got too tight to turn..

Mostly it's fine. Anyone think of a hacky fix? It's a screw on type cassette, I guess a bit of google might find me a fixie conversion. I take it proper single speed gears are better at keeping the chain in place?

Comments

  • Wooliferkins
    Wooliferkins Posts: 2,060
    It'll be your chainline. As you haven't got your rear mech holding your chain on the sprocket any deflection of the chain and it will pick up on whatever sprocket it touches first and let the ramps do the rest. A screw on BMX freewheel should go on your wheel then as long as your chainline is roughly straight you'll be fine
    Neil
    Help I'm Being Oppressed
  • Blue Meanie
    Blue Meanie Posts: 495
    Err, surely a fixie hack needs a track sprocket screwed on?
    FCN16 - 1970 BSA Wayfarer

    FCN4 - Fixie Inc
  • Wooliferkins
    Wooliferkins Posts: 2,060
    True, Blue. Took two mentions of singlespeeds and the current set up over the title.
    Neil
    Help I'm Being Oppressed
  • MichaelW
    MichaelW Posts: 2,164
    You can use a 1/2 link to adjust your chain length.
  • craker
    craker Posts: 1,739
    Guilty as charged m'lud.

    Sheldon Brown suggests that screw on cogs use the same thread as the screw on freewheel. So I'd screw the cog directly to the hub lock it with a lockring.. then to sort the chainline out move the hub along its axle and redish the wheel. Simples. That'll be me without that bike for a while then...
  • lae
    lae Posts: 555
    ^ it'll unscrew because your hub doesn't have a lockring - putting a fixed-cog on a hub without a lockring is known as a 'suicide hub'.

    I'd get a proper fixed-gear hub that can accept a lockring, or just keep it singlespeed with a BMX freewheel.
  • Blue Meanie
    Blue Meanie Posts: 495
    "That'll be me without that bike for a while then..." About 1 hour.

    Ref: Lockring. An old school BB (non-driveside) lockring will work on a 'Suicide Set-Up'. It's the same thread size/pitch and direction as a track sprocket/freewheel.
    Ref: Suicide Hubs. The late Sheldon recommends not using a lockring! (I don't understand either) But, you'll struggle to unscrew any gear (with your pedals/legs) over 75" that's been put together with a chainwhip. I'm running 69" and hardly ever unscrew my suicide hub (which took me about 1 hour to fettle together), but I do also have a front brake - just incase.
    FCN16 - 1970 BSA Wayfarer

    FCN4 - Fixie Inc

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