Every time I put on a new chain and rotate the crank the chain tension is perfectly equal throughout the entire rotation. After the first ride there are loose and looser spots. Very noticeable with my finger, but completely invisible to my legs. I don't care or worry about it. I adjust the slack to what I want at the tightest spot and forget about it. I've experienced the exact same thing on every motorcycle chain I've ever installed. I used the highest quality sprockets and chains that money could buy on my motorcycles and it was always the same thing. First time you gassed it hard the chain was looser in some spots. Personally, I believe the chains are the culprits, not the sprockets. 90% of the single speed bikes I see have the chains adjusted WAY too tight.