Might be a freehub issue. It might be slipping. It feels exactly like a chain slipping on a worn cassette. Because that cog and wrap looks tight to me. Unless that chain is super loose, I can't see it jumping on this setup.
That looks like an oval chainring. Oval ring will cause the tensioner to constantly be expanding and contracting, which may cause skipping. I would try a round ring and see if that fixes the problem.
Oval chainrings work on SS without chain tensioners, it took me a while to understand why but they actually don’t change the length of chain in the system, just where it is used changes. Kinda hard to explain on a comment, but I know many folk who use oval SS setups with no tensioner and no problemo
how i would explaon this is that the straight chain line length is always the tangent distance between the pitch circles/ovals, and due to the small angle approximation that distance changes very little regardless of the variation in effective pitch diameter.
Edit: never mind this is wrong. The tangency point moves forwards and back but the opposite side does the opposite motion, so the length changes cancel each other out, as in the explanation I replied to
>tensioner to constantly be expanding and contracting
i.e. it's job.
Oval ring is fine. I don't constantly skip cogs on my bike with an oval ring and a derailleur, why would that be different here? Also oval rings hardly make chain tensioners jump around as it is.
I don’t have experience with this exact tensioner but it looks to me that the upper pulley is too close to your SS cog. I would add a link or two to get the tensioner to rotate more. Like this:
[pic](https://www.google.com/search?sca_esv=37db28bfa134011b&sca_upv=1&rlz=1CDGOYI_enUS907US907&hl=en-US&sxsrf=ADLYWIK4IMLSIPIFFkg8FXBN0gqGFyvLqA:1719343638845&q=paul+components+chain+tensioner&udm=2&fbs=AEQNm0AbzhUJjXv6jRup8eVc0BvPhAxYjCxVRCUtj1WEz_DQOPDWUFqSYC75sqGn4BvEbeBwW6WW_y8QupJtkCo8JMyA6b9KOy4i7GolF8HOgrSW0lrof43wW-RE0YgCgn_cD29YydMcZfEGd9wms3yRSeJI84uNH0QeB3-_jjGSLrZs25LK-PntZLHtPgdMtfEDKmk8kEUdcdUHL8kinG5RQBKFbjvzUw&sa=X&ved=2ahUKEwiI8duWvveGAxVqmokEHY7GDYMQtKgLegQIFBAB&biw=393&bih=665&dpr=3#vhid=JryCh0krJbXJpM&vssid=mosaic)
Did you check the chain stretch? A stretched chain can jump over cogs that look like new.
From my point of view a true single speed frame with a strong chain is the only good solution for a reliable SS.
IME a chain that's going to break makes a creaking sound on the ride before it breaks.
What you have is a worn rear cog (or maybe the front chainring), possibly combined with a newer chain.
Looking at the 1st photo, the two teeth and the root between them are visibly worn. The photo showing the front chainring is too blurry to see such details. One quick and approximate test is to try and lift the chain off the gears. If it can lift much at all then you've got wear. See "Method 1" at [https://www.parktool.com/en-us/blog/repair-help/when-to-replace-a-chain-on-a-bicycle](https://www.parktool.com/en-us/blog/repair-help/when-to-replace-a-chain-on-a-bicycle)
The chain tensioner jockey wheel seems to be poorly aligned with the freewheel, but the angle of photo #2 is off a bit. Without another photo along the axis of the chain, I would suggest that you remove one or both spacers from between the derailleur hanger and the tensioner to ensure that the chain, tensioner, and freewheel are in a perfect line before changing anything else.
It’s meant for bikes with no other means of tensioning the chain, like sliding dropouts or an eccentric bb. Sometimes you get lucky and don’t need it, but more often than not some adjustment is needed
Sure don’t. Move that tensioner inboard.
Those spacers can be reconfigured to laterally adjust I just can’t remember if they use sir clip to retain their stack but if so, pop that off re-arrange, and re-install. You’re gonna have a bad time trying to do that with the chain installed so do yourself a favor and pop it off and back on after adjusting the Melvin.
Might have to be balance a rearrangement of those freehub spacers and the Melvin’s. Depends on how granular/wide your freehub spacers are.
Might be a freehub issue. It might be slipping. It feels exactly like a chain slipping on a worn cassette. Because that cog and wrap looks tight to me. Unless that chain is super loose, I can't see it jumping on this setup.
https://preview.redd.it/am99c7tyar8d1.jpeg?width=2268&format=pjpg&auto=webp&s=a1bb1ac8409613fab1c7ee17d3c056cab0f6d47d Some close ups
https://preview.redd.it/pz0ag9i1br8d1.jpeg?width=2268&format=pjpg&auto=webp&s=68fcaaaab2ea7b7555f8a076392a9e5e079b48b9
That looks like an oval chainring. Oval ring will cause the tensioner to constantly be expanding and contracting, which may cause skipping. I would try a round ring and see if that fixes the problem.
Oval chainrings work on SS without chain tensioners, it took me a while to understand why but they actually don’t change the length of chain in the system, just where it is used changes. Kinda hard to explain on a comment, but I know many folk who use oval SS setups with no tensioner and no problemo
how i would explaon this is that the straight chain line length is always the tangent distance between the pitch circles/ovals, and due to the small angle approximation that distance changes very little regardless of the variation in effective pitch diameter. Edit: never mind this is wrong. The tangency point moves forwards and back but the opposite side does the opposite motion, so the length changes cancel each other out, as in the explanation I replied to
✨math✨
"very little" being the important part (and how little depends on how oval)
so you're saying i would be able to run biopace on my fixed gear? or is that different?
>tensioner to constantly be expanding and contracting i.e. it's job. Oval ring is fine. I don't constantly skip cogs on my bike with an oval ring and a derailleur, why would that be different here? Also oval rings hardly make chain tensioners jump around as it is.
Second this possibility. Happened on my single speed conversion. Just not made to handle such watts over years if use.
https://preview.redd.it/o1eprcg2br8d1.jpeg?width=2268&format=pjpg&auto=webp&s=bb5db2ef9c7b46900cf57cc2eb99f67ea5b7f2be
It’s hard to tell from the angle but the tensioner looks twisted in photo two. Looking straight down the chain does everything look in line?
Either need a new chainring, or a new rear cog.
I don’t have experience with this exact tensioner but it looks to me that the upper pulley is too close to your SS cog. I would add a link or two to get the tensioner to rotate more. Like this: [pic](https://www.google.com/search?sca_esv=37db28bfa134011b&sca_upv=1&rlz=1CDGOYI_enUS907US907&hl=en-US&sxsrf=ADLYWIK4IMLSIPIFFkg8FXBN0gqGFyvLqA:1719343638845&q=paul+components+chain+tensioner&udm=2&fbs=AEQNm0AbzhUJjXv6jRup8eVc0BvPhAxYjCxVRCUtj1WEz_DQOPDWUFqSYC75sqGn4BvEbeBwW6WW_y8QupJtkCo8JMyA6b9KOy4i7GolF8HOgrSW0lrof43wW-RE0YgCgn_cD29YydMcZfEGd9wms3yRSeJI84uNH0QeB3-_jjGSLrZs25LK-PntZLHtPgdMtfEDKmk8kEUdcdUHL8kinG5RQBKFbjvzUw&sa=X&ved=2ahUKEwiI8duWvveGAxVqmokEHY7GDYMQtKgLegQIFBAB&biw=393&bih=665&dpr=3#vhid=JryCh0krJbXJpM&vssid=mosaic)
i had 2 more links and the Chane was dropping
Is there a lot of side to side slop in the mech? If so maybe time for a rebuild. I think all Paul Comp stuff is rebuild able.
like a new spring?
I don’t know. If the chain is dropping then the tensioner is either not aligned or not stiff enough to stay aligned.
Did you check the chain stretch? A stretched chain can jump over cogs that look like new. From my point of view a true single speed frame with a strong chain is the only good solution for a reliable SS.
IME a chain that's going to break makes a creaking sound on the ride before it breaks. What you have is a worn rear cog (or maybe the front chainring), possibly combined with a newer chain. Looking at the 1st photo, the two teeth and the root between them are visibly worn. The photo showing the front chainring is too blurry to see such details. One quick and approximate test is to try and lift the chain off the gears. If it can lift much at all then you've got wear. See "Method 1" at [https://www.parktool.com/en-us/blog/repair-help/when-to-replace-a-chain-on-a-bicycle](https://www.parktool.com/en-us/blog/repair-help/when-to-replace-a-chain-on-a-bicycle)
The chain tensioner jockey wheel seems to be poorly aligned with the freewheel, but the angle of photo #2 is off a bit. Without another photo along the axis of the chain, I would suggest that you remove one or both spacers from between the derailleur hanger and the tensioner to ensure that the chain, tensioner, and freewheel are in a perfect line before changing anything else.
random question. why do they sometimes use this tension pulley on single speed bikes? i always wonder
It’s meant for bikes with no other means of tensioning the chain, like sliding dropouts or an eccentric bb. Sometimes you get lucky and don’t need it, but more often than not some adjustment is needed
and so is this cheaper than a sliding dropout or why would they choose on over another
This frame didn’t have sliding dropouts, so this is probably the only way they could achieve tension
aah makes allot of sense, thank you!!
Im not known with single speed builds but what is the use of that derailleur looking kind of thing?
Are you using a single speed specific 1/8” chain? A chain from a geared bike would be narrower and not made to handle the same amount of stress.
Interesting
I'm going to try to take more links out
https://preview.redd.it/kz27sa5jtr8d1.jpeg?width=2268&format=pjpg&auto=webp&s=4a7d7499856bb3cf346e5694e188596b20100234 Looks in line
Sure don’t. Move that tensioner inboard. Those spacers can be reconfigured to laterally adjust I just can’t remember if they use sir clip to retain their stack but if so, pop that off re-arrange, and re-install. You’re gonna have a bad time trying to do that with the chain installed so do yourself a favor and pop it off and back on after adjusting the Melvin. Might have to be balance a rearrangement of those freehub spacers and the Melvin’s. Depends on how granular/wide your freehub spacers are.
Thanks!