Originally Posted by lz4005
Very small cogs can start introducing more drag from bending the chain around a smaller diameter. Not to mention that it is easier to throw the chain with fewer teeth engaged at any one time.
big rings/cogs last longer, you're chain is less likely to fall off. those are the obvious ones. everyone should read this though:
http://63xc.com/wakem/wakedriv.htm it'll change how you think!