I've been using Miche cogs for over 3 years now. They are very durable and one set has over 3000 miles without showing wear. I just changed my 10spd cogs from a 12-29 to 11-29. My other set from an 11-27 to the 11-29. They are fully customizable at a very reasonable cost. Also, if you damage 1 cog, you can just replace only the one, not a cluster or spider.