Todays thinner ramped chains only last between 3,000 and 5,000 miles as does the rear gear cluster. You need to make sure you keep your chain clean and lubed frequently with anything but wax based lubes. TriFlow, Finish Line Teflon Dry are two very good but low cost lubes; spending more for top line lube does not buy you any more mileage on your chains according to all the complaints I read on this forum about short chain life. If you keep the chain clean and lubed, that will make the chain last longer than anything else.