[WVJon75]

Ok so I've been riding my Monocog on the stock drivetrain for maybe 100-150 miles total with a couple of rides using an 18t redline cheapo cog before retreating to the 20t again.
Today I decide to try a 17t cog to ride around on the street. When I put it on and spun the freewheel I noticed resistance in one distict spot in the rotation in conjunction with a momentary tightening of the chain. Upon "breaking over" the tight spot the chain appeared to stick to the teeth of the cog and want to try to wrap around. If I look directly down upon the cog while freewheeling it I can see a VERY slight lateral movement which I also could see with the 20t cog. I did the same thing with the chainring and it too looks a hair off. This leads me to the following questions:

1)Could I just run a 1/8" chain to allow the imprecision of the chainring and cog?

2)Should I just replace the chainring?

3)Is the freewheel hub possibly warped causing the SLIGHT lateral movement in the cog? How much is tolerable?

 

[johnnyb]

Here's a quick check...is your chain too tight? It should spin around easily at least twice without any sort of rumbling or grindy noise. Is your cog on tight enough?

I'm not sure what a single speed chain width is but that is what you should be using. A shimano hyperglide type chain is narrower.

 

[WVJon75]

I'm using the stock chain which is a 3/32 and doesn't have really any room for misalignment.

 

[johnnyb]

Is the chain loose?

 

[WVJon75]

It is what I call "normal" tension but then again this is my first SS. I can move the chain up or down about 1/4" so about 1/2" total movement at least.

 

[johnnyb]

Okay, it might be a slightly bent cog or chainring or both. OR a tight chain. First check the chain, all the links should be slinky and smooth if its a new chain. Usually where the chain is connected is the tight one or for some reason you bent the chain laterally in a extreme manner. If its the cog or ring tooth, locate it and look for a burr or scuffed up edge and also if it is straight. I think these are steel bits, so you can use a flat edge plier and "coax" it back to true.

good luck.

 

[nbrennan]

I wouldn't be surprised if that slight lateral movement was accompanied by a local elongation in the diameter of the cog. Otherwise, it isn't round. This can make your chain tension go from perfect to bearing-grindingly tight. I dont know if it would cause the chain suck you described, but its something to investigate.

 

[WVJon75]

I wouldn't be surprised if those cheap cogs are out of round. Today I just went to the LBS and got a 1/8" SS chain and problem solved. I guess the extra width was enogh to tolerate the imperfections in the chainring and cog and possibly the chain line too.

Thanks guys