Out of ideas. Little help diagnosing chain skip?- Mtbr.com
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  1. #1
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    New question here. Out of ideas. Little help diagnosing chain skip?

    So I've been riding my Canfield Brothers EPO as SS with no issues, but I was looking to change up my ratio to suit my local trails a bit better. Now, I can't get the new setup to work without significant chain skip. Here is the setup that worked:

    - Race Face N/W 32T chainring (104 BCD)
    - Niner 18T Cog
    - Singulator (Push down)
    - Industry Nine Torch (non-SS) wheels

    This is the new setup I cannot get to work.

    - Absolute Black 36T Oval
    - Surly 20T cog
    - Singulator (push down)

    Because the 36T needed extra clearance, I had to add a BB spacer. This made me adjust the chainline. I have calculated and used a straight edge to check my chainline. Currently, my chainline is off by less than 1mm and the Singulator is in line with the cog. Unless I'm an idiot

    So far, I have tried 3 different chains (KMC SS, KMC 10-sp, & SRAM 11-Sp) to no avail. Singulator cannot push up because of the chainstay geometry (and how slack the chain is). Because of the derailleur hangar, I can't tighten the singulator any further. I can almost take out a link, but not quite. This makes the current chain quite loose. Without the tensioner, the chain still skips. I have tried 2 different freehub bodies thinking that could be the issue. Neither fixed the chain skip.

    I think my problem is tension. Next step will be to try a half-link(?) or different tensioner (DMR?)... or just throw on an 11-sp cassette and be done with it.

    Hopefully, I'm just screwing up something easy. Any suggestions?

  2. #2
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    I believe it's about chain wrap and if you're on the verge of being able to take a link out, then the system probably has inadequate wrap. Personally I'd try the half link.
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  3. #3
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    You can't use a half-link with a narrow/wide chainring.
    DMR won't work with a thru-axle, AFAIK. Think that requires a QR(?).

    What do you mean when you say that you can't tighten the Singulator further because of the derailleur hanger?
    You can't turn it further because the wrench hits the frame?

    If so, you may be able to change the orientation of the flats where the wrench grabs it by holding it in place while screwing the Singulator on. Seems like you might also be able to change it when reassembling from having it apart like to swap springs, but I'm not sure on that one. Would have to pull mine and check, but I'm at work on a double shift.

  4. #4
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    You can't use a half-link with a narrow-wide chain.

    Maybe it's the hub. Open it up and take a look at the pawls.
    Last edited by mack_turtle; 04-18-2017 at 05:35 AM.

  5. #5
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    Buy my Blackspire Stinger, too.

  6. #6
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    A half link with a N/W chainring?

    You won't be worrying about the back skipping teeth, that's for sure.

  7. #7
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    You cannot use the DMR tensioner with a thru axle frame. It has a little bracket that slides into the dropout that the QR skewer goes through before you can screw the QR nut on. I had to drill mine out so my DT Swiss 10mm thru bolt would work.

    Some gearing combinations just wont work when using a tensioner on a vert. dropout frame. I have been through this issue on my converted SS. I started with 32/22 combination with a DMR tensioner and quickly learned that ratio was too low for my local trails. I decided to go to a 20T cog but was not able to shorten the chain enough to use the tensioner in push up fashion, push down had insufficient chain wrap and would skip on climbs. Then I ordered a 19t cog thinking I would have no problem. After shortening the chain as much as I could the tensioner didnt have enough range to use in push up or down mode. Cog number three is 18T and the chain has just enough slack to install and use the tensioner in push up mode. Oddly enough, 32/18 is nearly perfect for me on all but the steepest and fastest trails around me.

    I said all that to say this..... Try going up or down a tooth on the rear to find a combonation that works. You most likely will have to compromise either on the flats or climbs.

  8. #8
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    Quote Originally Posted by mack_turtle View Post
    Buy my Blackspire Stinger, too.
    ^ this.

    (assuming all components are new) It sounds like your just not getting enough wrap/tension. The BB mounted stinger will push up and give you the desired tension. I'm a little surprised your having this issue with a 20t cog, but a loose chain and tensioner in push down mode make a weak combination. also, seems silly to use an 11sp chain on a SS. 8 speed chains are just as good and 1/4 the cost. just my $.02.
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  9. #9
    eri
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    With 414mm chainstays and 36x20 you need 46.73 links for correct slack. It is loose.

    Step up to 36x21 you'd be at 46.97 links which is perfect and you won't need a tensioner.
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  10. #10
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    Thanks guys. I counted 8 teeth engaged on the 20T with the Singleator in the push down, but the chain is still super slack. OwenM, you're right. When I tighten the Singleator, the wrench rotates until it hits the frame. I'll try tweaking this to have more spring tension, but I just don't think it'll be strong enough.

    All the pawls on both freehubs look good.

    eri, I will pick up a 21T and give it a try.

  11. #11
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    Quote Originally Posted by HaolErik View Post
    eri, I will pick up a 21T and give it a try.
    instead of spending $30 on a cog that will likely yield the same results, I'd spend $30 on a new tensioner.
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  12. #12
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    Problem is there's not many options for qualty tensioners with adjustable chainlines.
    A Stinger brings a lot of potential issues with it, due to the chainline it requires, tire clearance, and whether or not it will even clear the chainstay on that bike enough to tension the chain. Possible, but depends on several "ifs".

  13. #13
    eri
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    Quote Originally Posted by HaolErik View Post
    eri, I will pick up a 21T and give it a try.
    You have the sweetest bike evar. It ain't right to see it running a tensioner!

    For CSL I used the published spec of 414mm which computes that a 21t cog would be perfect.

    If you'd like a perfect precise answer can you measure the max vertical play in the chain, high to low, at the midpoint between bb and rear axle?
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  14. #14
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    Have you checked for binding or bent links in your chain?

  15. #15
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    Quote Originally Posted by maximo View Post
    Have you checked for binding or bent links in your chain?
    Never mind I just read you have used 3 different chains... Carry on.

  16. #16
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    do you have a threaded BB?

    Trickstuff

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  17. #17
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    make sure there is no play in the cog. Since you changed cog brands and positioning I'm thinking it may not be a snug if you had to replace some of the spacers.

  18. #18
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    Forgive me for the n00b question, but why would a single speeder set up with an oval chainring? Doesn't that mean there's slack in the chain for as much as half of the chain's travel around the ring? It would seem to me that the chain is susceptible to skipping the flatter the oval is in the revolution? In the very least, the Singulator will be bobbing up and down on every stroke with an oval ring.
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  19. #19
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    Quote Originally Posted by noisebloom View Post
    Forgive me for the n00b question, but why would a single speeder set up with an oval chainring?
    You misunderstand how oval rings work. Read some of this http://forums.mtbr.com/singlespeed/o...ed-932469.html

    A lot of ss riders have oval rings. By the way they are designed, there is no pronounced change in tension.

  20. #20
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    There's a definite change in tension, but I've never dropped a chain because of it. Even when my EBB moved and the chain got REALLY slack.

  21. #21
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    IDK if you have this resolved or not, but I've had hit-or-miss luck with Surly cogs. My suspicion is that if you aren't using a tensioner, they're great. But if you are, I've had skipping on a few different setups.

    On a bike that I was using a Melvin and derailer as a tensioner (not at the same time) I could watch the chain jump on the cog when really cranking hard.

    Max the cyclist on here remarked at one point that he had problems with Surly cogs using his Melvin as well.

    So my suggestion would be to try a different cog... but YMMV.

  22. #22
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    Quote Originally Posted by mack_turtle View Post
    You misunderstand how oval rings work. Read some of this http://forums.mtbr.com/singlespeed/o...ed-932469.html

    A lot of ss riders have oval rings. By the way they are designed, there is no pronounced change in tension.
    Fair enough. I just wondered if the oval ring was overlooked as a possible culprit.

  23. #23
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    Quote Originally Posted by mack_turtle View Post
    You misunderstand how oval rings work. Read some of this http://forums.mtbr.com/singlespeed/o...ed-932469.html

    A lot of ss riders have oval rings. By the way they are designed, there is no pronounced change in tension.
    Reading that thread, I think it's filled in what I was missing. With an oval ring of 34t, for example, it has the same circumference as a 34t circular ring, so in practical terms it introduces no slack in the cog. Got it now. Maybe I'll try one.

  24. #24
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    Quote Originally Posted by noisebloom View Post
    Reading that thread, I think it's filled in what I was missing. With an oval ring of 34t, for example, it has the same circumference as a 34t circular ring, so in practical terms it introduces no slack in the cog. Got it now. Maybe I'll try one.
    Yep. The chain still wraps around the same number of teeth on the chainring. There is movement, but it's minimal.

  25. #25
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    I have two single speeds running AB oval rings. There is definitely a noticeable change in tension in the "dead" parts of the oval, but I've never had a chain drop because of it.

  26. #26
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    OK, wait a minute here. You said you changed ratios to suit your local trails better. Problem is, you really didn't change it much. You went from 32x18, which is 1.78, to 36x20, which is 1.8. That's an unnoticeable change, just go back to your original gearing, which is about 1% harder.

  27. #27
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    Quote Originally Posted by bikeny View Post
    OK, wait a minute here. You said you changed ratios to suit your local trails better. Problem is, you really didn't change it much. You went from 32x18, which is 1.78, to 36x20, which is 1.8. That's an unnoticeable change, just go back to your original gearing, which is about 1% harder.
    Good point. I was moving to the 36t Oval to make it easier to change cogs based on my local trails. Currently, I got the 36x18 to work perfectly on a relatively flat trail. The 2.0 ratio is much better than the 1.78. However, yesterday, I just rode a trail with more hills and I had to go back to the 32x18 setup. Hopefully, my 21t Surly cog works out better, but it hasn't arrived yet...

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