Chain Vibration question
 

Hello there I was lubing my chain when I noticed that on certain points when I rotate the cranks the chain starts slack starts to vibrate(don't know if thats the right word) but it moves up and down rapidly. kinda crazy looking. My question is, is that normal? Stiff chain or something? I'll try to post a vid of it tommorrow.

It is normal, but not safe. Mine gets really tight and super loose, and I have dropped the chain tons of times. Still waiting on my new crank and chain ring.

is your chain tension correct? your cog/chainring may be out-of-round or eliptical, take some measurements. how about the chainline, if it isnt consistently straight through he full revolution, something may be bent. all of these conditions will require some difference corrective action.

Ah i see, what would be a solution. New cog/chainring? whichever is out of whack?

its your chainring, its not perfectly concentric with the axis of rotation of the cranks. its not a terrible thing, lots of bikes have this, but if its causing you to drop your chain, then you should probably switch to a higher quality chainring

Okay cool, I havent dropped the chain yet just noticed it and nothing bad has happened from it. Just wondering what it was. Thanks guys

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If you're using a road chainring it may be slightly out of round. Try loosening the chainring bolts and cranking it around a bit, then retightning; this can sometimes reduce the wobble effect.

A bona fide track ring is usually made to tighter tolerances than most road rings, if a new ring is an option for you.