Originally Posted by
Rolla
There's a tool that measures cog wear, so you don't have to solely rely on trial-and-error. And some shops will refer to your chain wear in percentages, because that's how they interpret the chain wear indicators that have .075 and .05 markings on them.
cxwrench is correct about the terminology, but IMO it's nothing to fire your mechanic over.
Cog wear indicator:
Chain wear indicator (note markings on right):
These are the two devices I use at our LBS. No, we do not just "run up the bill" with claims of worn parts. I don't say "stretch" or "%wear". We consider 1.0 end of life and best to change at 0.5. I say "half worn out" or "half way to end of life" or "it's the most worn chain I've ever seen". Eh, I've only actually said that once.
And I do not just put a new chain on then try to get it to skip on an old cassette or FW. Thats a huge waist of time at $75/hr. That's how to run up the bill. I check things then talk to the customer. I like that chain checker but you need to use it a lot and get a feel for it. And i am also puzzled at the price. I made one for my home shop - bit of scrap cherry wood, length of surplus new chain, a zip tie and good to go. I'm now looking for a length of 11spd chain to make another one. The Rohloff checker will not work on 10spd or 11spd cogs (nor 12, 13, 14 spd when we get there)