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Discussion Starter · #1 ·
Does anyone else have problems with their chain 'catching' on the tips of the their cog's teeth and then 'popping' as the link jumps into place? I am not having major issues; it happens about 1 - 3 times per hour of riding but is annoying when it does.

This never happens with my WI Freewheel or Tomicog; I think this is because the teeth have more of a point to them rather than a flat spot on the peaks so there is nowhere for the chain to catch.

I have tried Surly and Endless cogs (8 speed SRAM chain on everything) but wanted to post up before buying anything else. All of the cogs with sharper looking teeth seem to be the cheap stamped cogs. If anyone else has this issue, did you ever find a chain/cog combo that eliminated it?

My chain line is good; I have even tried moving it slightly inside/outside thinking the chain might tend to jump one direction and I could offset it (no luck). I can get rid of the popping if I run my chain really tight but then I run into all the issues with having one's chain too tight so it's not really a solution.

I think a pulley style tensioner would eliminate the problem as it would take up the movement in the chain and ensure the chain is straight when rolling onto the cog but I'd really rather not run this type of system if possible.

Thanks in advance for any feedback/suggestions.
 

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A couple of things come to mind , how concentric is your chainring ? How is your chainline ?
 

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bmw said:
Does anyone else have problems with their chain 'catching' on the tips of the their cog's teeth and then 'popping' as the link jumps into place? ...
Mine does that occasionally, at least I think it's the same thing based on your description. Maybe not. My chain sounds like it's about to unship but then it kinda pops and everything is fine. Is that the same as your situation?

It's just something I put up with. I'm running 36x24 on a 29er, Surly ring, Onza Buzz Saw 24t granny ring on the rear w/GCA, Sram 8spd chain.

Seems to do it less if I pay close attention to chain tension (I make this as tight as I can without "going over the line") and it does it less if I lube the heck out of my chain, which I do without hesitation because of the wet Oregon slurry I ride through this time of year.

--Sparty
 

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Discussion Starter · #6 ·
AZ.MTNS said:
A couple of things come to mind , how concentric is your chainring ? How is your chainline ?
Chain line is good. I haven't checked if the chainring is round but I use the same chainring with my Tomicog and WI freewheel without issues.
 

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Discussion Starter · #7 ·
Sparticus said:
Mine does that occasionally, at least I think it's the same thing based on your description. Maybe not. My chain sounds like it's about to unship but then it kinda pops and everything is fine. Is that the same as your situation?

It's just something I put up with. I'm running 36x24 on a 29er, Surly ring, Onza Buzz Saw 24t granny ring on the rear w/GCA, Sram 8spd chain.

Seems to do it less if I pay close attention to chain tension (I make this as tight as I can without "going over the line") and it does it less if I lube the heck out of my chain, which I do without hesitation because of the wet Oregon slurry I ride through this time of year.

--Sparty
This sounds like exactly the same thing; slight feeling like the chain could jump then a pop back on the cog. I am running a Stylo chainring with Endless cog, 32x19 on a 29er.

I have also found that chain tension as tight as possible and lots of lube helps but does not eliminate the problem.

I think if I could just get a cog that had the tooth profile of the WI freewheel I would be okay but haven't found one.
 

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Word of warning

I just put my 69'er in the shop this morning. It is hypothesized that I tore up my hub because I had the chain too tight. The rep is in the area tomorrow and I should find out how much damage there is.
 

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Chim Chim said:
I just put my 69'er in the shop this morning. It is hypothesized that I tore up my hub because I had the chain too tight. The rep is in the area tomorrow and I should find out how much damage there is.
Exactly why I'm careful to never "go over the line" when it comes to chain tension. In fact, there should never actually be any "tension." There should just be as close to zero up & down movement in the middle of the chain run (between ring & cog) as possible. But if the chain is actually under tension, one is asking for all kinds of problems.

Good luck with the rep -- hope excessive chain tension is not the culprit in your case.

--Sparty
 

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Discussion Starter · #10 ·
Good luck with your hub. Mine has been giving me problems since day 1, even had the whole thing replaced under warranty but that did not solve anything.
 

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Everyone is asking how old the chain is - I'm going to ask, "How old is the cog?" One other thing that it could be, if the chain/cog are similar age and wear, and the basic chainline is good, is that sometimes, under a load the frame may flex a bit, as well as axles and other bits and pieces (including cranks and rings) and those little bits of flex can potentially cause a chain alignment issue that is sporadic and temporary... My XXIX in certain cases under a heavy load will flex a bit and I have had the chain "snap" into the trough on the ring or cog. 1/8" chain/cog/ring is the best way to minimize this, IMO.
 

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chain suck is usually caused by the chain's pitch not matching the cog's pitch due to wear or chain stretch. stamped cogs are likely to have that issue more since it's harder to hold tight tollerances with a punch. CNC machined cogs should be closer, unless they're sloppy with tool wear or have an extremely loose machine. The pointy teeth shouldnt matter much, if you look at a true ANSI cog, they're far pointier than that, and they dont have issues catching the chain.


Also, when under extreme torque, like when climbing, your chainstay is probably going to flex some, causing your chainline to be off and your chain to be loose. This can cause that poping sound, as the chain will try to ride up the side of the cog (like it's shifting) then it slaps back down into place when some tension is relieved. This really cant be solved 100%, but i always try to have my cog ever so slightly inboard (towards the hub), so when the chainstay flexes, my chainline isnt as far off.
 

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Discussion Starter · #13 ·
Thanks everyone for the insight.

ATBScott - I have had this issue since the drivetrain was new: new cog, new chain, new chainring all together.

As for flex, I am riding a Sinister Simon Bar. I'm sure there is some flex but it is one of the beefier frames. Also frame flex would not explain why it happens with the Surly and Endless cogs but not with the WI freewheel or Tomicog. This is why I think it has to do with the cog and specifically the teeth.

Notice in the pics how the WI comes to more of a point while the Surly has a flat top on the teeth. If I pull the chain to the side while spinning the cranks, the Surly will catch the chain on this flat spot and then the chain pops back into place. When I do the same with the WI, the peak on the tooth seems to thread the chain into place and it does not cause the pop.

So just to reiterate, the popping only happens with the Surly and Endless cogs, the WI freewheel and Tomicog do not have the issue. I am sure it is not the hub. I thought it was and had it warrantied to no avail.

ISAR - do you do custom tooth profiles? Any chance of getting a cog with a WI tooth profile so I can test this out? :) (seriously...)
 

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could be that your chainline isnt the same with the WI as the surly or tomicog, which is why you're having problems with the 2 cogs that go on one type of hub, and no problem with the type that goes on another. You might be off just enough, and in the wrong direction, to be causing issues.
I could do a custom profile down the road when i reopen, but i'd like to see you fix the issue first as it really shouldnt be happening.
 

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Discussion Starter · #17 ·
ISuckAtRiding said:
could be that your chainline isnt the same with the WI as the surly or tomicog, which is why you're having problems with the 2 cogs that go on one type of hub, and no problem with the type that goes on another. You might be off just enough, and in the wrong direction, to be causing issues.
I could do a custom profile down the road when i reopen, but i'd like to see you fix the issue first as it really shouldnt be happening.
The chain line on the Surly and Endless is good; I've tried it both inboard and outboard to see if I could offset the movement but it didn't work. I might just give up on free hubs or check back with you on the custom tooth profile later on.
 

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bmw said:
The chain line on the Surly and Endless is good; I've tried it both inboard and outboard to see if I could offset the movement but it didn't work. I might just give up on free hubs or check back with you on the custom tooth profile later on.
No reason to give up on freehubs, some of the strongest guys i know (pretty high ranking pros) run them with no issues.
What chainring are you running? What shape is it in? Any tight/loose spots, or is it equal tension throughout the whole revolution of the crank?
 

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Discussion Starter · #19 ·
ISuckAtRiding said:
No reason to give up on freehubs, some of the strongest guys i know (pretty high ranking pros) run them with no issues.
What chainring are you running? What shape is it in? Any tight/loose spots, or is it equal tension throughout the whole revolution of the crank?
I run the stock chainring from the Stylo SS cranks. I actually replaced the bottom bracket, cranks, and chainring when this popping started (when I got my I9's) because I thought some of those older parts were responsible.

It's hard for me to imagine the popping is caused by anything other than the cog as the chainring, chain, flexing, etc would all cause issues with the freewheel and fix cog if they were the source of the issue.

I've had 3 shops double check my chain line, wear and tear, etc. All of the shops had basically the same suggestions and observations that are present in this thread.

I'm still convinced the tooth profile is the problem. Given the same chain tension and chain line, if I push the chain to the side and try to derail it while spinning the cranks, the chain gets stuck on the flatter teeth and then pops into place as I spin the cranks, the sharper teeth do not catch the chain.

I could be wrong, and I am certainly making too big a deal out of it but I have been chasing this issue for over a year and have tried almost everything at this point.
 

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if you have tight spots and loose spots in the chain caused by an out-of-round chainring, it can most certainly make some strainge noises. The fact that the cogs with the taller teeth help just tells me that they're just tall enough for the chain not to get on top of it when your chainring gets to a low spot and your chain becomes loose.
This is not normal, there should be no reason why you cant run the same equipment as everyone else if everything is as it should be.
 
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