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  1. #1
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    Chain skip after cog change?

    I have an '03 P2, and just put on that Gusset ER SS conversion from Jenson, and now my chain skips. Previously, I had the stock 8 speed cassette back there, though I was running a SS w/ a chain tensioner (ratio 32:15). Now, with the same tensioner, and a 16 tooth cog out back (now a 2:1 ratio), the chain skips whenever I crank hard. I did a search and it seems the usual culprit for chain skip on an SS is too long of a chain, but since I moved to a slightly larger cog, I don't think this is the problem. The chainline is almost perfectly straight (as straight as I can get it with the spacers Gusset provided), and I've adjusted the tensioner numerous times. Any ideas? Thanks, -Chris

  2. #2
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    Quote Originally Posted by big_johnson
    I have an '03 P2, and just put on that Gusset ER SS conversion from Jenson, and now my chain skips. Previously, I had the stock 8 speed cassette back there, though I was running a SS w/ a chain tensioner (ratio 32:15). Now, with the same tensioner, and a 16 tooth cog out back (now a 2:1 ratio), the chain skips whenever I crank hard. I did a search and it seems the usual culprit for chain skip on an SS is too long of a chain, but since I moved to a slightly larger cog, I don't think this is the problem. The chainline is almost perfectly straight (as straight as I can get it with the spacers Gusset provided), and I've adjusted the tensioner numerous times. Any ideas? Thanks, -Chris

    ramped cog?
    worn chain?

  3. #3
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    Quote Originally Posted by roadiegonebad
    ramped cog?
    worn chain?
    Well, the bike is only two months old (when I bought it in October, it was brand new somehow, even though it is an 03), so I'm pretty sure the chain is OK, though I could go measure to be sure. And pardon my ignorance, but what does "ramped" mean? Thanks, -Chris

  4. #4
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    Ramped........

    Quote Originally Posted by big_johnson
    Well, the bike is only two months old (when I bought it in October, it was brand new somehow, even though it is an 03), so I'm pretty sure the chain is OK, though I could go measure to be sure. And pardon my ignorance, but what does "ramped" mean? Thanks, -Chris
    is a gearie cog or chain ring, the ramps aid shifting.
    A true SS cog will not have the ramps.
    "As a rule, men worry more about what they can't see than about what they can."
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  5. #5
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    So the teeth on a ramped cog would be shaped like this /\ (roughly) if viewed from behind the bike, and a true SS cog's teeth would be more like II from behind? If this is the case, then my new cogs aren't ramped, they are designated SS pieces

  6. #6
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    No not really.....

    Quote Originally Posted by big_johnson
    So the teeth on a ramped cog would be shaped like this /\ (roughly) if viewed from behind the bike, and a true SS cog's teeth would be more like II from behind? If this is the case, then my new cogs aren't ramped, they are designated SS pieces
    If the cog is ramped you'll see the ramping cut on the side of the cog,
    where as if it is not ramped the side of the cog where the teeth are will
    be smooth.

    Look at the cogs on the cassette you took off the bike, you'll see the
    ramping on the side of the cogs.
    "As a rule, men worry more about what they can't see than about what they can."
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  7. #7
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    Quote Originally Posted by V V V
    If the cog is ramped you'll see the ramping cut on the side of the cog,
    where as if it is not ramped the side of the cog where the teeth are will
    be smooth.

    Look at the cogs on the cassette you took off the bike, you'll see the
    ramping on the side of the cogs.

    OK, I get it now. I was a little confused after the first explanation, but it's clear to me now. Thanks for being patient . Either way, the new cog isn't ramped. Any thoughts? -Chris

  8. #8
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    Cool-blue Rhythm

    Even though the bike is relatively new, I'd replace the chain anyway. Stock chains on even mid-range bikes are typically crap. I broke the chain on my FSR on the second ride, and I've stopped to help others out on the trail with drivetrain problems on new bikes a couple times, and have been amazed at the horrid quality of the chains. The most memorable was a woman on a brand new Fuel, where the side plates were basically falling off the rivets. These chains are certainly not SS worthy, and should be replaced before it strands you out on the trail.
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  9. #9
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    Quote Originally Posted by big_johnson
    The chainline is almost perfectly straight (as straight as I can get it with the spacers Gusset provided)
    Are you sure this isn't the problem?
    The Gussett doesn't allow for much fine tuning of the chainline. That's my best guess.

  10. #10
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    Do you have a straight chain line?

    Is your cog compatible with the chain? Happened to me that I had a BMX cog and tried to use a 9spd chain. Those 2 aren't compatible, replaced the cog with a 9spd compatible one and the problem was solved.

    My .02

    PS: Don't remember the chain sizes but believe that they're 1/8 (BMX) and 3/32 (8-9spd).

  11. #11
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    Quote Originally Posted by pcrap
    Are you sure this isn't the problem?
    The Gussett doesn't allow for much fine tuning of the chainline. That's my best guess.

    Could be, but I don't think the chainline was perfectly straight before, either. I was running it on the 3rd smallest cog, which was closer to the outside of the hub, close to where my single cog is positioned now. Would adjusting the position of the tensioner compensate for a slightly off chain line? Or, does anybody know of any skinnier cog spacers that I could use to fine tune the chainline?

    It is possible that the cog is not compatible with the chain, it never really occurred to me before. Would this make that big of a difference? The chain is a stock shimano 8 spd, shortened for SS use. Would I be better off with a BMX chain? Or does anyone think that shortening my current chain even more could help? Right now, the top and bottom segments of chain run parallel to eachother, but I could shorten it to where the chain slopes slightly upward towards the rear,

  12. #12
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    Quote Originally Posted by big_johnson
    Could be, but I don't think the chainline was perfectly straight before, either. I was running it on the 3rd smallest cog, which was closer to the outside of the hub, close to where my single cog is positioned now. Would adjusting the position of the tensioner compensate for a slightly off chain line? Or, does anybody know of any skinnier cog spacers that I could use to fine tune the chainline?

    It is possible that the cog is not compatible with the chain, it never really occurred to me before. Would this make that big of a difference? The chain is a stock shimano 8 spd, shortened for SS use. Would I be better off with a BMX chain? Or does anyone think that shortening my current chain even more could help? Right now, the top and bottom segments of chain run parallel to eachother, but I could shorten it to where the chain slopes slightly upward towards the rear,
    Just go to your LBS and get a single speed chain, less than ten bucks. The spacing on a narrow 8 or 9 speed chain will not work on that cog. That should solve the skipping problem.

    cruz

  13. #13
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    Failure to communicate?

    Quote Originally Posted by big_johnson
    Could be, but I don't think the chainline was perfectly straight before, either. I was running it on the 3rd smallest cog, which was closer to the outside of the hub, close to where my single cog is positioned now. Would adjusting the position of the tensioner compensate for a slightly off chain line? Or, does anybody know of any skinnier cog spacers that I could use to fine tune the chainline?

    It is possible that the cog is not compatible with the chain, it never really occurred to me before. Would this make that big of a difference? The chain is a stock shimano 8 spd, shortened for SS use. Would I be better off with a BMX chain? Or does anyone think that shortening my current chain even more could help? Right now, the top and bottom segments of chain run parallel to eachother, but I could shorten it to where the chain slopes slightly upward towards the rear,
    First of all if you bought a Gusset SS conversion, it should have come with two BMX cogs; a 16 and an 18 I think. Are you now using a BMX cog? My first thought was chain line as the Gusset only gives you two chain lines. Also it sounds like you were using a tensioner with one gear on a cassette before you switched over to the Gusset; is that correct? If so the other gears could have stopped the chain from skipping. All this being said your chain needs to be as short as possible. If you can take out a link do so. If not hopefully you have a Singleator with a push up mode. This usually solves most skipping problems. If not replace your tensioner and re-install your old derailleur ala Keith Bontrager. Derailleurs make much better tensioners that so called "SS tensioners".

    1G1G, Brad
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  14. #14
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    Cool-blue Rhythm

    Quote Originally Posted by big_johnson
    Right now, the top and bottom segments of chain run parallel to eachother, but I could shorten it to where the chain slopes slightly upward towards the rear,
    That statement says a lot. You're obviously running your tensioner in pull down mode. You need to be running the tensioner in push up mode.

    With the taller and squarer teeth of the BMX cog, the chain jumping shouldn't be an issue if it wasn't before, except that if you're running the tensioner in pull up mode and installed a bigger cog, you may less chain wrap than before. If you're running your tensioner in push down mode wrap is probaly a little more, but still less than with pull up mode. Either way, it's a recipe for getting a chain to jump under load. With the taller and squarer teeth on your new cog, it's importent to have a decent chain. Chains don't have to be expensive, but they do have to be quality. A cheap chain under load, if the chainline isn't spot on, may have problems meshing smoothly with the new cog. If you look at the side plates of a good chain, you'll see that the inside edges of the side plates are bevelled in order to facilitate the entry of the cog's teeth into the chain's links. If these edges aren't bevelled, that could be a big part of the problem.

    Look, an SS drivetrain isn't rocket science. There's really only a few parts to it. If you have a brand new cog, and the chain is jumping under load, it's either chainline, not enough chain wrap, or a crap/worn chain. If your chainline is pretty much straight, and your tensioner is pushing up, there's only one thing it can be, your chain. If your tensioner isn't pushing up, set it up so it is. If you can't because of the chain length, shorten the chain or choose a different ratio so you can run a tighter chain.
    Last edited by Bikehigh; 12-27-2004 at 03:06 PM.
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  15. #15
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    Quote Originally Posted by cruzthepug
    Just go to your LBS and get a single speed chain, less than ten bucks. The spacing on a narrow 8 or 9 speed chain will not work on that cog. That should solve the skipping problem.

    cruz

    BS... and totally unnecessary. Gusset (DX) cog is meant to work on any 3/32" chain; that means 8- or 9-spd. Many here use 8-spd chains w/o problems. SS-specific chain is no better and no worse.

    Make sure the cog and chain are compatible (1/8" vs 3/32"). Otherwise, re-check your chainline. A tensioner can make up for chainline slop.

  16. #16
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    Quote Originally Posted by Bikehigh
    Look, an SS drivetrain isn't rocket science. There's really only a few parts to it.
    Well that's easy to say unless its your bike and it's not working. I've tried pretty much every conversion method in the FAQ (except the floating chain ring), had problems with a few, but managed to get them all to work. On my converted Bontrager I first spaced out a standard (8/9 sp) freehub, a BMX cog and a Singleator in the push down mode (no problems). I then switched to freewheel hub and the chain started skipping with a 16T and push down Singleator. It was then I discovered 32:18 was the magic combo or 32:16 with a half link. When I tried a freewheel flip flop hub 16T and 18T freewheels, necessitating enough chain for an 18T cog, but needing a tensioner for the 16T cog, the skipping went away when I used the Singleator in the push up mode. I mention the Surly Singleator because most of the other tensioners only work in one mode.I've also installed a Gusset kit on my buddy's Kona who also had the magic 32:18 combo and it worked fine.

    1G1G, Brad

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    Wow, lots of info being thrown out here. Thanks for the help fellas, I'm learning quite a bit. OK, to answer a few questions: Yes, I am running the 16T BMX cog that came with the gusset kit. I was also using a tensioner with a cassette for SS previously.

    Now here are a few questions of my own: Why would a tensioner in push-up mode help? Is it because it creates more wrap around the cog? Secondly, I do not beleive my tensioner has push-up mode (I'll go check in a minute, but it is doubtful), so would making the chain as short as possible with the existing tensioner improve wrap?

    The chain is pretty cheap(ly made), so if shortening it doesn't work, I may go buy a higher quality SS or BMX chain at the LBS and see if that helps anything.

    I may also put on the 18T cog out back to see if that changes anything, but I do think that 2:1 is the ideal ratio for me. This is my DJ/4x/urban/BMX style race bike, and 2:1 is exactly what I need for those situations.

    Anyways, I really appreciate the help and suggestions, I will go see if I can put the tensioner in pull-up mode, and shorten the chain a bit. I'll hopefully report back soon

  18. #18
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    ramped cogs

    Quote Originally Posted by big_johnson
    Well, the bike is only two months old (when I bought it in October, it was brand new somehow, even though it is an 03), so I'm pretty sure the chain is OK, though I could go measure to be sure. And pardon my ignorance, but what does "ramped" mean? Thanks, -Chris
    might as well change all three cog ,chain, and chain ring,why take the chance.usually they
    all wear together so just changing one is not going to do it .
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    Well, problem solved (I think). All I can say is thank God for horizontal dropouts (actually called track fork ends, as I just learned). Anyways, I just got rid of the chain tensioner (it couldn't go into push-up mode, and my chain could not be shortened anymore), and actually used the dropouts to tension the chain. Now, my only problem is the fact that I have QR's back there, and I should probably get a solid nutted axle (right?). The chain is staying relatively tight when I go out and crank on it for a while, but the QR is still slipping a little. How much play in the chain is normal for this set up? Is a nutted axle something a LBS would have in stock? I figure that if I get one of those and a pair of chain tugs, I'll be set for SSing. Thanks for the help, everyone

  20. #20
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    New question here. Dude your killing me!

    Quote Originally Posted by big_johnson
    Well, problem solved (I think). All I can say is thank God for horizontal dropouts (actually called track fork ends, as I just learned). Anyways, I just got rid of the chain tensioner (it couldn't go into push-up mode, and my chain could not be shortened anymore), and actually used the dropouts to tension the chain. Now, my only problem is the fact that I have QR's back there, and I should probably get a solid nutted axle (right?). The chain is staying relatively tight when I go out and crank on it for a while, but the QR is still slipping a little. How much play in the chain is normal for this set up? Is a nutted axle something a LBS would have in stock? I figure that if I get one of those and a pair of chain tugs, I'll be set for SSing. Thanks for the help, everyone
    You ony need a tensioner with verticle dropouts. Since you have a frame with horizontal fork ends you never needed a tensioner. As far as the QR goes, go with a steel Shimano, most find they work just fine (make sure you scrape off all the paint on the contact surface so the QR can bite into metal. As far as tensioning the chain about 1/2" play at the tightest point works for me (make sure you turn the crank 1/4 turn @ time to find the tight point). I never used chain tugs with QR's so you'll have to ask someome else.

    1G1G, Brad
    Last edited by aka brad; 12-28-2004 at 10:58 AM.

  21. #21
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    Quote Originally Posted by aka brad
    You ony need a tensioner with horizontal dropouts. Since you have a frame with verticle fork ends you never needed a tensioner. As far as the QR goes, go with a steel Shimano, most find they work just fine (make sure you scrape off all the paint on the contact surface so the QR can bite into metal. As far as tensioning the chain about 1/2" play at the tightest point works for me (make sure you turn the crank 1/4 turn @ time to find the tight point). I never used chain tugs with QR's so you'll have to ask someome else.

    1G1G, Brad
    uh, you seem to have switched your terms up a bit there, brad. you need a tensioner when using VERTICAL dropouts, since verts provide no way to tension the chain (unless there is an eccentric BB involved).
    And also, some QRs work great, others don't. Steel QRs generally get more bite, but upper end Shimano and Campy skewers with alloy ends snug down pretty tight due to the design of their cam. Best bet to elimintae slip is always a nutted axle, but if you want to use tugs, they usually work just fine too. Just more involved if removing the wheel, like for a tube change.

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    What you talking about Willis?

    Quote Originally Posted by pedalsoftly
    uh, you seem to have switched your terms up a bit there, brad. you need a tensioner when using VERTICAL dropouts, since verts provide no way to tension the chain (unless there is an eccentric BB involved).
    And also, some QRs work great, others don't. Steel QRs generally get more bite, but upper end Shimano and Campy skewers with alloy ends snug down pretty tight due to the design of their cam. Best bet to elimintae slip is always a nutted axle, but if you want to use tugs, they usually work just fine too. Just more involved if removing the wheel, like for a tube change.

    Don't know what you mean ("edit" is a wonderful thing) .

    1G1G, Brad
    Last edited by aka brad; 12-28-2004 at 12:04 PM.

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    Well, I just ordered a nutted axle from the LBS, and when it arrives, I will also throw some chain tugs on there just to cover all the bases. Thanks for everybodies help, I'm sure I'll have some more questions later

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