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single speed questions

unscarredunscarred Posts: 208
edited February 2010 in The workshop
I'm planning a single speed commuter based on a very old mountain bike (no sus). Last time I went "ghetto" and it didn't work out great, so this time I'm going to try and do it properly. Hence these questions:

Most single speeds I read about are 700C - will I need a different gearing ration for a 26er?
What's the best way to find your "ideal" ratio?
Can I put a different cog on either side of a regular wheel so I've got some flexibility, or does this require special kit?
Do tug nuts work on the forward facing diagonal drop-outs, or are they only for track-style rear facing drop-outs? Is there an alternative?
I'm debating V-brakes vs CX-style centre-pulls - which is more reliable, which is more effective?

This is a commuter which gets left outside overnight at the station, so needs to be able to take a lot of punishment. Reliability and low maintenance are my top concerns.

Cheers
FCN 6 in the week on the shiny new single speed.

FCN 3 at the weekend - struggling to do it justice!

Posts

  • nicklousenicklouse Posts: 81,520 Lives Here
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • 1) use sheldon brown's gear inch calculaor to find a gear you're comfortable in on your current bike - then calcualte the ratio needed to give you the same inches on a 26" bike

    2) you need a special flip-flop hub to get a cog on each side

    3) tug nuts are fro track ends only. No real alternative for forwardf drop outs, just do your nuts up very tight (q/r is not a good idea as difficult to get tight enough)

    3) V-brakes - easier to set up. Can't use with drop-bar levers unless you bodge them. "CX Style" cantil;ever brakes - harder to set up and to keep running smoothly, but can use drop bar levers.
    <a>road</a>
  • Oddjob62Oddjob62 Posts: 1,056
    Gear Ratio calc
    http://software.bareknucklebrigade.com/ ... pplet.html

    Best way to find your ideal ratio? If you've currently got gears then just find the one you feel most comfortable with. Then get a chainring and cog that gives the same GI (the calc gives you many choices).

    Tugs aren't necessary, i've never used them on either front facing, or trackends.
    As yet unnamed (Dolan Seta)
    Joelle (Focus Expert SRAM)
  • laelae Posts: 555
    I'd disagree about the QRs El Presidente - my two singlespeeds and my fixed gear both use QRs (as does nearly everyone on the LFGSS forums) with no problems at all. They're banned on velodromes but it's because they have rules against protuberances that could cause injury.
  • 1) use sheldon brown's gear inch calculaor to find a gear you're comfortable in on your current bike - then calcualte the ratio needed to give you the same inches on a 26" bike

    2) you need a special flip-flop hub to get a cog on each side

    Thanks, I thought it would be something like that. Interestingly, Sheldon did suggest putting two different SS cogs on the freewheel side of a conversion - manual gear change, i.e. loosen wheel, move chain over by hand, retighten wheel. Obviously means you don't have a prefectly straight chainline.
    3) tug nuts are fro track ends only. No real alternative for forwardf drop outs, just do your nuts up very tight (q/r is not a good idea as difficult to get tight enough)

    I've been UTFS on LFGSS and turned up at least one person using Surly Tuggnuts on forward dropouts, and many interested in alternatives - one fabricated his own. Doesn't look like the Tuggnuts are an ideal solution, and they're quite expensive.
    3) V-brakes - easier to set up. Can't use with drop-bar levers unless you bodge them. "CX Style" cantil;ever brakes - harder to set up and to keep running smoothly, but can use drop bar levers.

    I won't be using drops, but maybe bullhorns, so I guess it's down to a sheer reliability issue. I will go ask Sheldon what he thinks...
    FCN 6 in the week on the shiny new single speed.

    FCN 3 at the weekend - struggling to do it justice!
  • Right, gear ratio, find what you're comfy with, i run 46-16 on my 700c cx bike, 32:16 on my ssxc bike, 36:16 on my jump bike and 42:16 on my god awful rat bike (26") Bear in mind though that tyre choice really does effect the comfort of a gearing. My CX bike was lovely at 46:16 on 23mm race slicks, but is a touch heavy on 32mm cx tyres.

    You can get double-free rear hubs, then you can run varying ratios, but you can have issues with chain length if they're wildly different. TBH man up and don't bother.

    Run v-brakes, there are plenty of drop bar v-levers, or you could just run regular levers as interrupter style ones.
  • Oddjob62 wrote:
    Gear Ratio calc
    http://software.bareknucklebrigade.com/ ... pplet.html

    Best way to find your ideal ratio? If you've currently got gears then just find the one you feel most comfortable with. Then get a chainring and cog that gives the same GI (the calc gives you many choices).

    Tugs aren't necessary, i've never used them on either front facing, or trackends.

    Thanks for the advice Oddjob, that calc should be useful. I do my entire commute in two or three gears ATM, so I guess I'll just take the middle one!

    Maybe tugs shouldn't be necessary, but my previous attempt at SS was scuppered by the wheel's habit of jumping forward in the drive side dropout, jamming the tyre against the chainstay. I physically could not do the nuts up tighter, and I'm a big bloke! Any idea why I had this problem?
    FCN 6 in the week on the shiny new single speed.

    FCN 3 at the weekend - struggling to do it justice!
  • wgwarburtonwgwarburton Posts: 1,863
    unscarred wrote:
    Maybe tugs shouldn't be necessary, but my previous attempt at SS was scuppered by the wheel's habit of jumping forward in the drive side dropout, jamming the tyre against the chainstay. I physically could not do the nuts up tighter, and I'm a big bloke! Any idea why I had this problem?

    Cheap nuts? Good quality track nuts are generally advised to address this problem.

    The interface between the locknuts on one side of the dropout and the tracknuts on the other determines how well the axle stays planted. If the dropouts present nice clean grippy faces and the nuts have good knurling then it all Just Works.

    Cheers,
    W.
  • Oddjob62Oddjob62 Posts: 1,056
    Cheap nuts? Good quality track nuts are generally advised to address this problem.
    .

    I'd have to point towards your nuts as well. I've never had a wheel move. My first fixed was a converted raleigh as well and never had problems with that either.
    As yet unnamed (Dolan Seta)
    Joelle (Focus Expert SRAM)
  • Oddjob62 wrote:
    I'd have to point towards your nuts as well.

    I'd prefer you didn't, I'm very self-conscious :D

    Seriously though, that's a nice easy and cheap fix if that's all it is, and certainly the place to start.

    Cheers guys!
    FCN 6 in the week on the shiny new single speed.

    FCN 3 at the weekend - struggling to do it justice!
  • wgwarburtonwgwarburton Posts: 1,863
    unscarred wrote:
    Oddjob62 wrote:
    I'd have to point towards your nuts as well.

    I'd prefer you didn't, I'm very self-conscious :D

    Seriously though, that's a nice easy and cheap fix if that's all it is, and certainly the place to start. ..

    Yup. Have a go at your dropouts while you're in there- you don't want grease, oil, dirt or loose paint between the nuts & the frame. Dropouts should be relatively soft metal (you don't want them to crack, after all), so the knurling on the nuts ought to bite into the metal and grip (proper track nuts have collars, which set against the dropout and let the nut turn to tighten).
    If necessary, you might even file the faces of the dropouts to ensure a good grip, but be wary of inviting rust...

    Finally, on a more obscure note, I thought I needed chain-tugs last year, because my chain kept slacking off (lazy B***) and I thought the axle must be creeping. Turned out that it was the bearings on the hub gradually disintegrating into the shell....!
    Needless to say, the truth was revealed on a wet, dark morning, on my way to catch a train to a new job. I don't recommend this as a way to make a good impression.

    Cheers,
    W.
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