I got this chain for my 3/32" fixed gear bike, thinking I could essentially get 2 chains for $8. Well, my rear cog makes loud "clacking" sounds with the rotation of the wheel. I just got a new crankset/chainring combo today too (Sugino RD) and now it's making some sort of metal scratching/sandy sound.
Does anyone know whether this is the chain's fault? I took a closer look at the chain today and it says "KMC Narrow Z-40". Narrow?? I hope this isn't more narrow than normal chains and is causing more wear. Upon inspection of my EAI cog (brand new), it has worn off the brown plating on every other tooth so that bare metal is exposed. Is this normal?
I'm not intimately familiar with that chain but I have used the Nashbar KMC narrow 6/7-speed chain on my fixed (3/32" EAI cog) with no problems. Your fixed has run OK with other chains and started having these problems with the new chain? I wouldn't think that the chain is too narrow but maybe it's just narrow enough to cause problems if your chainline isn't perfect or if the cog is warped, bent, or misaligned.