I know chains can be like this – but surely not to this extreme. My chain ring is not that worn either. Recently replaced the freewheel if that makes any difference.
Chain is very tight and very loose in different spaces. Impossible to find a sweet spot / any consistency. Any ideas?
byu/Appropriate-Value618 inbikewrench
by Appropriate-Value618
15 Comments
Hmm, a cheap, out-of-round cog or chainwheel?
That’s the tightness that you want. I ran a loose chain once and almost died lmfao. For me that’s the best setup.
Chainring may not be centered on crank
Basically need to revisit your Sheldon.
Rings can often be made to achieve bettery concentricity by careful application of a hammer. You can squirm them around on their bolts. The basic procedure is find the tightest spot, then imagine a line between the rear axle center and the BB center. With the chain still on, gently bonk the ring on its front end such that the strike is along that line. Then find the next worse etc. It often doesn’t take much to make a big difference.
You can try Sheldon’s method- slightly loosen all the chain ring bolts and lightly tap the front edge of the chainring with a rubber mallet, as you slowly turn the crank. Tap where the chain tightens up of course. Then retighten. May not help!
Is this a single speed? Mine acts the same way. I thought it was because the chainring was slightly oval?
The question you need to ask is if the chain gets tight at the same spot of the crank or at the same sport of the rear axle.
Is it possible that this bike has a floating rear axle with chain tensioners? If so it is probably too tight right now.
There is [runout](https://en.wikipedia.org/wiki/Run-out) somewhere in the system, and you need to find out where it is. Find a way to place a visual reference point near the chainring and the sprocket, spin them both, and look for both radial and axial runout. Once you’ve identified where it is, you’ll have to see what you can mess with to correct for it. Something could be seated incorrectly, something could be bent, there could be a manufacturing defect, or it could be that there’s just slop in the assembly that you can play with if you break it a little bit loose.
Looks normal to me for a single speed. You don’t want the chain to much looser or you risk it falling off.
Now if you feel like there is resistance when peddling I would move the rear wheel IN a tiny bit further which will give you a loser fit and you should be good
There’s definitely a tight link where you touch the chain the second time
If this wasn’t the case before and your chainring/crank hasn’t changed, there’s a number of things that could be wrong:
– cog on the freewheel is elliptical/out of round
– stiff links in chain
– chain was loose before your replacement, and you never noticed that your chainring was elliptical
I think you have some stiff links. Remove the chain and run it over your finger, you’ll find the links that don’t smoothly move. Flexing the chain back and forth with your thumbs (sideways, perpendicular to the direction a chain normally moves) will hopefully loosen them up. Then lube your chain. Good luck.
I don’t know if this would be enough to cause this, but your chain appears to have a section with a few stiff links.
In your video, each time you find higher tension, I can see a stiff link. At 0:07, it is literally the link you touch with your finger, at 0:17 there’s a stiff link just three links to the right, and at 0:20, the pin to the left of your finger is stiff.
In response to the stiff links which people have picked up on. This is true, however I have tried with another chain and still the same problem.