Before going further, lets make sure you don't have a 3/32" (derailleur) chain on a 1/8" (classic single speed) sprocket. Loosen the rear wheel and push it forward to slacken the chain and gently push any inner link onto the sprocket. It should freely go to the bottom with visible clearance between the inner plated and tooth.
You can also do an eyeball test. Reach into your pockets for a comparison gauge. The teeth of 3/32" sprockets are about the width of a Quarter, and 1/8" sprocket teeth the width of 2 dimes.
If you do have a chain/sprocket mis-match buy a 1/2x1/8" single speed chain and you'll be good to go.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
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Last edited by FBinNY; 07-11-10 at 02:13 PM.