Originally Posted by exavid
It takes very little off center on the sprocket to make the chain go slack and tight. On my 2 stroke bike the tension goes from 1/4" slack to almost 3/4" as the wheel turns. There was very little off center when I put the wheel on the bike. I'll take it off eventually and get that sprocket right on the money but right now it's good enough. I think the thing might have shifted a bit in use which isn't impossible since it's only held by a rubber sandwich clamped to the spokes. If you have as much as 1/16" off center on the sprocket it's going to make a fairly large amount of change in chain tension as the sprocket is turned. That's a good argument for an idler pretty close to the sprocket. On my bike there's no idler so I keep a watch on the chain tension. I like running without an idler because it quiets the bike and makes it easier to pedal.
Never knew that even 1/16 of an inch would distort the chain. Well I guess I'm going to take the wheel off tonight and try to center it up just right because it is very annoying hitting 26 and just have the chain start to scream and feel the bike jerking back and forth. Thanks for the help.