Originally Posted by Iride01

The common Chain checkers only measure between the opposite sides of the two rollers. And that really doesn't matter as much since they'll "float" into place as they engage the cog. Shimano and a few others make a chain checker that measures more accurately to the same side of each roller.

However with my Park chain checker, it's always been close enough and I use it for a quick check, then when it shows the chain wearing to the point yours is, I'll double check with a steel scale or tape and measure to the same side of the pins to see how far beyond 12" they are apart. A 1/16 inch more than 12 inches is almost .5% wear. 12 x 0.005 = 0.06 and 1/16" = 0.0625


I'd expect someone that puts a lot of power into the pedals to wear out the chain faster. Lugging up a hill in high gears using all your leg muscle particularly bad, IMO. Also, if you cross chain in the large front and large rear, that might add more wear.

Regardless, I'd consider anything under 2000 miles as bad chain life. I usually get 4000 or more out of a 11 speed. My older bikes with 5 and 6 speeds would see 8000 miles... but that admittedly is just a guess.