I recently purchased a Fantom Cross Uno to use as a winter commuter/around town beater. It came with a freewheel which is fun for tooling around and hopping curbs but the novelty is wearing off and I'm gonna set it up as a fixed gear soon. I'm thinking about getting this one http://www.amazon.com/Avenir-Fixed-G...r+cog+15+tooth The last cog I had was the 17 tooth version and I used it for two years through every season. I estimate that it had well over 2000 miles on it before the old bike got stolen, and that includes grinding on lots of salt and sand. The last time I examined it there were obvious signs of wear but not nearly as bad as I expected for the amount of abuse it got.

What makes something like a Dura Ace, All City, or Surly cog more than twice the price of the one I linked? Do they honestly hold up that much better or is it about branding? Weight is not a concern for me. If it's worth the extra money for the extended lifespan I'm all for spending a bit more but I just don't have the first hand experience with more expensive cogs to justify the difference.