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Thread: set up help

  1. #1
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    set up help

    Hi all,

    I've been trying to set my Cotic BFe up as a single speed to try it out. I've checked the FAQ, but couldn't quite find what i needed.

    I'm using a 34t E.Thirteen chain guide up front, and a 18t cog on the rear. I'm also running a jockey wheeled tensioner.

    My problem is, that the chain 'jumps' as it comes up and over the top of the cog, when I'm applying a bit of force to gain speed, or going up a slight incline. I've tried using a single speed chain, and also as i saw mentioned on here an 8 speed chain, but i have the same problem with both.

    I've also tried adding and removing a few links to see if it was a problem with tension, but it keeps happening.

    Has anyone got any ideas? I'm all out!

    Cheers,

    Tom

  2. #2
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    I had this happen with a frame I had set up with a surly tensioner and it ended up being the chain. If you cut the chain, check the link that you re-pinned, sometimes they crush the link and make it so it doesn't bend very well. If this happened push it 1mm through then, go to other side of chain and push it back even with the outer setting on your chain tool. If there is any tight spots in the links and they don't move freely, when you run a tensioner it will pop.

  3. #3
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    Thanks for your reply.

    I've checked the chain, and all the links move freely, adding the 2nd new chain should have eliminated the skipping if it was the chain. But it still skips!

    I've tried running it without the tensioner, but i can't quite get the chain tight enough, as it's a vertical drop out. I almost need half a link.

  4. #4
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    Have you checked your derailleur hanger to make sure your tensioner is perfectly aligned with the chain? After bending my derailleur hanger, I started having the same problem you're experiencing even after getting my hanger back to what appears to the naked eye to be straight. I'm currently trying to find a magic gear set-up so I can run without a tensioner, but that's not going so well either . . . .

  5. #5
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    Quote Originally Posted by Tolk83
    I almost need half a link.
    maybe a half-link in your chain would do it. have you tried one of those?

    i had a Surly tensioner with the "down" spring in it cause the same problem. the spring crapped out on me after a few rides. if there is not enough tension in the spring-loaded tensioner you are using, it will do that.

  6. #6
    meatier showers
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    How old is your cog? If it is old and the chain is new, they may not play well together. Also sounds like it might be a chain wrap problem. The more the chain encircles the cog, the less likely it is to skip.

    Good luck.

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    They're both brand new. I've been trying to sort it all day now, and all I've managed to do is break my tensioner! Without the tensioner the chain is either too slack, or unable to link together. As it's a vertical drop out frame, I don't know how I'll make it work. Only thing i can think of is a half link chain, as I'll be able to get it tighter.

    I've been running gears for years now, and can build bikes ect, i thought setting up a single speed would have been easy as! How wrong i was!

    Thanks again for all the advice though guys!

  8. #8
    Ovaries on the Outside
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    I'm guessing chainwrap too. There is that option of zip tying your tensioner to the chainstay so the chain is pressed toward the chainstay, rather than pushed away from the chainstay.

    Is the cog SS specific? Those big teeth make a big difference.

  9. #9
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    Yep it's a SS specific from SuperStar components. I'll have a few more beers and give the zip tie idea a whirl!

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    Bit of an update, I've done away with the tensioner (fubar'd anyway) and have managed to get the chain on tight. If i squeeze the chain as it passes top and bottom halfway between the chain ring and cog, i get about 1cm movement (if that makes sense) so it's on there pretty tight. Does this sound about right? I can post up a picture if needed.

    Thanks again guys,

    Tom

  11. #11
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    1 cm is fine as long as your cranks spin freely, i usually get about 2- 2 1/2 revolutions before it stops. You'll be able to tell if it's binding though. I usually have about 2cm of play up and down on my chain half way between my front chainring contact point and rear cog.

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    Hmm it's binding and not spinning hardly at all, but my non drive side bottom bracket decided to pack in yesterday. New one should be here tomorrow, so hopefully it's just that.

    If they still don't spin freely, would it suggest it's too tight? What would be the consequence of this, chain snapping easily?

  13. #13
    Ovaries on the Outside
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    Quote Originally Posted by Tolk83
    Bit of an update, I've done away with the tensioner (fubar'd anyway) and have managed to get the chain on tight. If i squeeze the chain as it passes top and bottom halfway between the chain ring and cog, i get about 1cm movement (if that makes sense) so it's on there pretty tight. Does this sound about right? I can post up a picture if needed.

    Thanks again guys,

    Tom
    Turn the cranks and check for tight spots, or really loose spots. Chainrings, crank spiders, cogs... they are not always perfect. It would be awesome if you stumbled on a magic gear.

  14. #14
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    Quote Originally Posted by Tolk83
    Hmm it's binding and not spinning hardly at all, but my non drive side bottom bracket decided to pack in yesterday. New one should be here tomorrow, so hopefully it's just that.

    If they still don't spin freely, would it suggest it's too tight? What would be the consequence of this, chain snapping easily?
    If it isn't loose enough it will also be a ***** to pedal. And things will break.

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    Quote Originally Posted by Tolk83
    Hmm it's binding and not spinning hardly at all, but my non drive side bottom bracket decided to pack in yesterday. New one should be here tomorrow, so hopefully it's just that.

    If they still don't spin freely, would it suggest it's too tight? What would be the consequence of this, chain snapping easily?
    In the long run it may make more sense to figure out your tensioner problem, as I recently learned the hard way when I developed tensioner problems and tried to set my bike up with a magic gear. I tried pedaling a too-tight chain onto the front chain ring and bent the ring in the process. By running a too-tight chain you can also damage your freewheel and your bottom bracket.

    My new chain ring arrived today. After trying three different cogs, varying chain lengths, and a half-link, I'm abandoning my quest for the magic gear. Instead of running a clunky Forte' tensioner, I've been inspired by the "homebrew" thread to engineer my own.

    Good luck with your issues. Please be sure to post your solution.

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    Just tried a 32t, from the 34t i was using and it's too slack. Maybe a 33t would be the 'magic gear', but i don't want to have to spend out to see if it works or not!

    The fettling continues!

  17. #17
    Ovaries on the Outside
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    Just give up and send me your bike.

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    Haha, there's been times today where I've felt like throwing the thing out!

    However, i think i may have sorted it! I've changed to the 32t ring, and have zip tied the broken tensioner so that it makes the chain wrap round the cog a fair bit more. It's got a bit more slack than it had before with the 34t, and spins more freely. I'll wait for the new bottom bracket to show up tomorrow to give it a proper spin. Then order a new chain and swap back to the 34t, as i stole the 32t from my girlfriends kona (She doesn't know yet!)

    Thanks everyone for the warm welcome and the help!

  19. #19
    meatier showers
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    What you want is a Forward Components Eccentric Bottom Bracket for conventional-sized BB shells. It is the ultimate chain tensioning system for vert-drop frames.

    Do a search. Bad Mechanic posted an awesome photo journalistic description / review many moons ago.

    --sParty
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  20. #20
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    I'll look into that, cheers!

  21. #21
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    Quote Originally Posted by Tolk83
    Just tried a 32t, from the 34t i was using and it's too slack. Maybe a 33t would be the 'magic gear', but i don't want to have to spend out to see if it works or not!

    The fettling continues!

    I use this to get an idea if it's doable, maybe it will help
    software.bareknucklebrigade.com/

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