Originally Posted by
sideshow_bob
I don't really understand the concept of rotating chains - you end up with multiple chains you have no idea what the mileage is on. One chain, a ruler and a weekly clean ...
The idea of rotating is that chains stretch faster than the cassette wears. So by rotating through 3 chains the cassette wears along with the chains and you don't have the problem of putting a new chain on an overly worn cassette, reducing chain skip. In theory the cassette and 3 chains are all worn out at the same mileage. I'm not sure that this is a valid assumption.
I just broke a 10 speed Ultegra chain with 1,100 road miles on it. I thought this was was way too soon and did some research on chain life on the web. Most people were getting 2,000 to 3,000 miles on a 10 speed chain which gives a cassette and 3 chains (in rotation) a life expectancy of 6,000 to 9,000 miles. Some people were getting less than 1,000 miles on a chain. I think 12,000 miles for 3 chains is plenty.