Bizarre Single Speed issue, ideas please??- Mtbr.com
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  1. #1
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    Bizarre Single Speed issue, ideas please??

    I will attempt to make this brief yet convey the issue although I have a lot of information to provide...sorry!

    Bike: Salsa Fargo 29er with Surly 32T ring and Surly 17t cog. Surly SS kit on the hub and a Surly Singleator tensioner in push up setting. Perfect chainline. Chain is a SRAM 8 speed chain 3/32. This setup has worked flawlessly, and still is about 1k miles later except for this weird problem...

    So, I loved the Fargo setup so well I converted my Rockhopper to the exact same setup. Decide to replace the chain on the Salsa Fargo while I'm at it since it's my daily commuter. New chain is a KMC 8 speed 3/32. The new chain skips! Can't even ride it cruising. So I try a new SRAM chain, same one as before, and it skips! So I reverse the chain ring and cog thinking maybe that had premature wear, still skips with both chains. Throw on the old chain, runs smooth as silk!!! I even tried swapping Singleator tensioners since I have a brand new one for my Rockhopper conversion. Still skips with a new chain, runs perfect with the original chain. Yet this exact setup ran perfect when the first chain was new!
    It looks like somehow tension is being transferred over the chain ring and it then pushes the tensioner down lessening the wrap over the cog and causing it to skip, but only with the new chain.

    Now the kicker, my Rockhopper runs flawlessly with either new chain and it's using the exact same rings cogs and tensioner setup!

    I am at a complete loss here and I hope I get some ideas from you guys! Thanks!!

  2. #2
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    Oh and I have tried adjusting chain tension a million times! Makes no difference if it's tight as a rubber band or loose as a goose.

  3. #3
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    I bet the old chain on the Salsa is longer than the new one. Sprockets and chains wear together, and as the chain elongates it wears the chainring and rear cog teeth to fit it. When you put a new tight chain on the spacing on the sprockets doesn't mate up and you get skipping under pressure.

    I could be just the rear cog that is bad, less teeth to distribute the load = quicker wear, but you may have to replace the front ring too.

  4. #4
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    Quote Originally Posted by J.B. Weld View Post
    I bet the old chain on the Salsa is longer than the new one. Sprockets and chains wear together, and as the chain elongates it wears the chainring and rear cog teeth to fit it. When you put a new tight chain on the spacing on the sprockets doesn't mate up and you get skipping under pressure.

    I could be just the rear cog that is bad, less teeth to distribute the load = quicker wear, but you may have to replace the front ring too.

    Its my understanding that by flipping the chain ring and cog on the Surly Stainless SS rings its like starting with a new ring/cog? Also these are Stainless steel extra thick rings that shouldn't have any wear at only 1000 miles or so. My SRAM chain the original one hardly even indicates any wear on a Park chain measuring tool. Thanks for your reply it very well could be a chain/cog wear issue it just seems so unlikely.

  5. #5
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    Check that the cog on the rear is not loose (even slightly). The lock ring may not be perfectly tight (like it was when it was new).

    The difference between when the Fargo was new and now, is that the cog or the chainring may have shifted. Even a tiny shift can cause problems.

  6. #6
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    Quote Originally Posted by wjphillips View Post
    Check that the cog on the rear is not loose (even slightly). The lock ring may not be perfectly tight (like it was when it was new).

    The difference between when the Fargo was new and now, is that the cog or the chainring may have shifted. Even a tiny shift can cause problems.
    I did this when I reversed the cog and chainring to rule out cog or ring wear. Thanks though!

  7. #7
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    Quote Originally Posted by bikebeard View Post
    I did this when I reversed the cog and chainring to rule out cog or ring wear. Thanks though!
    Ok. And make sure the wheel is perfectly aligned in the drop outs. If it is not centered just right, could cause a problem as well.

    But, ya, chain stretch could also cause this type of problem. How many miles did you put on the old chain?

  8. #8
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    Quote Originally Posted by bikebeard View Post
    Its my understanding that by flipping the chain ring and cog on the Surly Stainless SS rings its like starting with a new ring/cog?
    No, spacing will still match the chain that was running on it. I agree 1000 miles doesn't seem like a lot but a worn cog/ring is the most likely explanation for the problem you describe. I can't think of another.

  9. #9
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    Quote Originally Posted by J.B. Weld View Post
    No, spacing will still match the chain that was running on it. I agree 1000 miles doesn't seem like a lot but a worn cog/ring is the most likely explanation for the problem you describe. I can't think of another.
    Would a worn chainring and a new chain allow transfer of chain tension over the ring? If so that would make sense because somehow when the new chain is on there is downward tension transferred to the chain tensioner.

  10. #10
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    Things to check:
    Chainring bolts, are the all tight?

    The surly single speed cogs are not symmetrical along the teeth axis. Flipping the cog will move the teeth and may mess up the chainline. Try adjusting for this with the spacers. The surly cogs are so thick that even a small change can cause issues.

  11. #11
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    Quote Originally Posted by dompedro3 View Post
    Things to check:
    Chainring bolts, are the all tight?

    The surly single speed cogs are not symmetrical along the teeth axis. Flipping the cog will move the teeth and may mess up the chainline. Try adjusting for this with the spacers. The surly cogs are so thick that even a small change can cause issues.
    I moved a spacer to adjust for the cog offset. Chain ring bolts are tight.

  12. #12
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    Quote Originally Posted by bikebeard View Post

    New chain is a KMC 8 speed 3/32. The new chain skips! Can't even ride it cruising.

    Throw on the old chain, runs smooth as silk!!!


    This info tells you that the problem can't have anything to do with chainline, chainring bolts, chain tension, etc., it has to do with the chain because it works perfect with the old one and terrible with the new one. Aside from worn sprockets the only other explanation I can think of would be a buggered link on the new chain and that would be obvious, and totally bizarre that both of the new chains you tried would have one.

  13. #13
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    Just for kicks, have you considered putting a 1/8" chain on there? The wider chain might help....

  14. #14
    one chain loop
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    i agree with j.b., most likely worn cog and chainring is not lining up with the new chain.

    with the new chain on, check for gaps and spaces between your chain and chainring/cog.
    everything sucks but my vacuum cleaner.

  15. #15
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    I tried a 1/8 chain from the get go when I first went to SS and it skipped and the 3/32 worked great. I will try my new chainring off of my Rockhopper this weekend and see if that cures the problem although you'd think just flipping the ring would have done the same thing.

  16. #16
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    Also maybe check the new chains for tight links?

  17. #17
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    Just remember that it's at least as likely- probably more so, that the rear cog is to blame. You may have to do both.

  18. #18
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    Re: Bizarre Single Speed issue, ideas please??

    Will it skip while mounted in a bike stand? That would let you visually see what is happening.

    Swap the chainring and cog one at a time off of your Rockhopper over to your Fargo. That should narrow it down to either the cog, chainring or possibly both.

    Sent from my HTC One using Tapatalk 2

  19. #19
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    Very few variables here. I'm going to agree whith what others have said - chain ring and/or cog is worn. Replace everything at the same time. In my experience, SRAM 8 speed chains stretch/wear more quickly that the 8 speed KMC chains I've used. Good luck.

  20. #20
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    I will be quite upset if they have worn so quickly. The reason I went to SS and the Stainless cog and ring was for durability and simplicity. At $30 a cog and $50 a ring that is not cheap!

  21. #21
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    Quote Originally Posted by bikebeard View Post
    I will be quite upset if they have worn so quickly. The reason I went to SS and the Stainless cog and ring was for durability and simplicity. At $30 a cog and $50 a ring that is not cheap!
    I run a motorcycle chain on my bike mostly because I like things overbuilt so in this past year this has not been a problem. In the past I had major issues with wear.


    The big issue is that wear happens quickly when chains get dirty. Especially with narrow bicycle chains dirt can really accelerate wear.

    Leep the chains clean and replace them often. If you never let your chain wear the cogs for a very long time. If the chain wears to the point where it has grown the cog/ring teeth can wear in a very short time.

    With dirt and abrasives I have seen chains wear out in around 600 mile. Once the chain as worn to the point where it is longer then the cogs/rings you are in trouble. The cog and ring will wear to match the chain regardless of how they are made. Sure a steel cog might last longer then an aluminum cog but if paired with a worn chain revolution will load up the teeth and cause the valleys to grow such that it will skip later when you put on a new chain.

    It sounds very much like you have worn the cog and ring. Get a new cog/ring and compare them to what you have. Also get a chain wear checker and use after every few rides. Good luck and expect to replace chains more often in the future.

    Thicker chains will handle wear better because there is more metal vs. the same amount of dirt. Even with good chains it is still important to keep things clean and lubricated.

  22. #22
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    A motorcycle chain. That's cool. I bet it's pretty heavy though. But it should last a long, long time.

  23. #23
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    I'm betting that the new chain is binding on the chainring or cog, or both. Remove the chain and see if it wraps around the chainring without forcing it on. Do the sane for the cog. Also check clearance and fit on the tensioner pulley.
    I see hills.

    I want to climb them.

  24. #24
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    Btw, I've had new 1/8" chains bind on a worn 1/8" cog before. Causes weakening of the chain and it broke very quickly. If binding is the cause if the problem, get another chain.
    I see hills.

    I want to climb them.

  25. #25
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    Re: Bizarre Single Speed issue, ideas please??

    I have no personal experience with Surly chainrings but I've seen/read where quite a few people on this forum have run into issues with their chainrings.

    Sent from my HTC One using Tapatalk 2

  26. #26
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    If I were a betting man, this is a wear issue. Keep in mind that if you were on a geared bike, you'd be distributing the wear over at least two rings up front, and 8 cogs in the back for that 1000 miles you're talking about, and depending on the chain, how you ride, etc. you may have to replace all that (front rings, and rear cassette, possibly even RD cogs) when you replace the chain. We used to "double the life" of cassettes and rings by buying two chains with new gears and swapping them out every month, so you had two chains worn about the same amount, and when you wore those chains out, the rings and cassette were done.

    Still, looking at cost, go price the rings and cassette you'd be replacing if it were a geared bike. Now look at your cog/ring cost for this bike again. Still cheaper, I bet. You can either keep riding with the old chain for a while (save the new one) or you can replace everything. If you opt to replace everything, try the two chain trick. I haven't bothered to try that yet with my SS, nor am I doing it at the moment with my geared bike, but we used to swear it worked, so I guess it did.

  27. #27
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    Well I replaced the chainring and cog with a Surly 35t ring and 18t cog. Installed a new SRAM 870 chain as well. Everything runs perfect. I will try the run two chains and rotate them out monthly. Surly swears you should be able to run a chain into the ground on their stainless rings and just replace the chain with a new one but that seems to not be the case. I went with a higher tooth count to hopefully limit the wear.

  28. #28
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    I dunno... I've gone through many new chains without changing my cogs (even cheapie ones).

    I still think you have an underlying issue with your drive train.

  29. #29
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    Quote Originally Posted by wjphillips View Post
    I dunno... I've gone through many new chains without changing my cogs (even cheapie ones).

    I still think you have an underlying issue with your drive train.
    Time will tell. The old cog and ring looked brand new. No shark toothing or obvious wear marks. I am running my chain tension at about 1" deflection up and down so pretty loose. Chainline is perfect. I do use a Gusset slink half link but I don't think that could cause a weird problem.

  30. #30
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    Quote Originally Posted by J.B. Weld View Post
    I bet the old chain on the Salsa is longer than the new one. Sprockets and chains wear together, and as the chain elongates it wears the chainring and rear cog teeth to fit it. When you put a new tight chain on the spacing on the sprockets doesn't mate up and you get skipping under pressure.

    I could be just the rear cog that is bad, less teeth to distribute the load = quicker wear, but you may have to replace the front ring too.
    X2....you can't just mix and match worn drivetrain components and expect it to all work properly.

    Quote Originally Posted by pulsepro View Post
    Very few variables here. I'm going to agree whith what others have said - chain ring and/or cog is worn. Replace everything at the same time. In my experience, SRAM 8 speed chains stretch/wear more quickly that the 8 speed KMC chains I've used. Good luck.
    Yes. Surly chainrings and cogs have never given me problems, quite the opposite they run very smooth and last a long time. I love KMC SS specifice 3/32" chanins too! Even cheap stamped steel cogs have done decently so far, aluminum chainrings have not lasted very well for me and the minimal weight loss is not worth the decreased life on my SS or geared bikes.
    Get off the couch and ride! :)

  31. #31
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    So this is weird....

    I went with a new Sram PC870 when I installed the brand new chainring and cog and it has worked great, no more skipping issues. The plan was to just rotate chains every few weeks to increase the life of the chainring and cog. I have that brand new KMC 8 speed chain mentioned in the first thread so I installed that last night and...SKIP! doesn't work! Same issue on brand new chainring and cog! Something is going on. If I had the money I'd buy another Sram PC870 and try it. I only have a couple hundred miles max on the new ring, cog, and chain. My rockhopper is still running great with the KMC chain and Surly ring and cog. I've swapped tensioners between bikes and everything. Chain tension is perfect, chain line perfect, chainring bolts tight, wheel on tight. It's almost as if my Salsa frame doesn't like KMC chains lol.

  32. #32
    one chain loop
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    It doesn't make sense. Try a different wheel, your freewhel might be shot.
    everything sucks but my vacuum cleaner.

  33. #33
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    That is a kicker. I agree with fishcreek, you say it's a new cog so I doubt that's it but if it were me I'd want to find out what the heck is going on and the most reliable way is to switch parts and confirm results. I don't have a lot of experience with them but my friend has a Surly chainring that hates certain chains, it doesn't skip but it chain sucks like it was coated with glue. I'd try that same chain with a different ring and see what happens if it's an option.

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