does this cog look like its done 200 miles?

i got this cog to replace my current one, the picture on the thread i got it from only shown oneside and it was all black, and seemed good, seller stated that it done less than 200miles from new,
does it look like its done <200 miles??

sorry for the annoying cog related question in 2 days!

thanks
kirk

https://www.dropbox.com/s/hcoza6eb3xjj4q7/20120906_003454.jpg

It doesn't really look that worn to me, but I think you've got to take these 'only done a hundred miles' claims a bit cynically anyway. Likewise, 'buttery smooth' etc. Depends what price you paid, I suppose.

You also have to factor in that the chain-line might not have been perfectly straight, plus a used chain or gritty chainwheel would also cause premature wear.

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Yeah I'd be happy to accept that it's done about 200 miles. Plenty of life left.

Yes. Looks almost new.

Just looks like the finish has worn off (perfectly normal). The teeth look fine.

cooll, thanks guys:)

Interesting that every 2nd tooth is more/less worn than the one beside it.

But yeah, it's just the coating that's worn, the tooth shape looks fine.

I get a similar thing on my polo bike, every other tooth seems to pick up more dirt, I assume it's something to do with the ratio (even teeth front/back) and them always being on the inner chain links rather than the outer ones.

I'm not sure that makes as much sense as it does in my head.

is it cos of the chainline?

it's because the sprocket has an even number of teeth. Half the teeth are meshed between inner plates of the chain so get rubbed, and if the chain has an even number of links and isn't taken off it's always the same teeth. Half links or odd tooth-numbered sprockets would break the pattern. The number of teeth on the chainring is irrelevant to what happens to the sprocket (but if it's even too then the same thing can happen there).

It is actually kinder to the chain to try and stay with this pattern than to attempt to even out the wear.

Bad chain-line doesn't create the alternating pattern, but would make it stronger on one side.

That's what I was trying to say.