Originally Posted by sweep242
Typically 1/8 (thicker one) is for track/bmx, better suited for single speed,stronger.
3/32 (skinnier one) is for geared bikes mtb/road.
Depends what size cogs your running. my ring, cog & chain are 3/32 no problems so far, but i here bigger is better!
Noise wise, i've been very unhappy with the 1/8'th stuff. My road bike was ninja silent on 3/32. And my chainline is 100%. I don't really see any reason to go to 1/8th over 3/32. Cogs/chainrings (especially 130bcd front chainrings) available everywhere in 3/32 and sram pc48's (3/32 chain) used to be $10 a pop from PBK.
As soon as I have enough money i'm ditching my 1/8 rear cog/chain for a 3/32 chain/cog combo. Can't really go wrong with either.