Originally Posted by
xroadcharlie
Until I joined BF I didn't know bikes chains even wore out. My old (1987) cheap mountain bike had 8,000 miles on it. I never changed the chain and seldom oiled it.and the drive train worked perfectly when I gave it away.
My new (2018) bike went into the shop for some repairs with only 1,000 km on it and the service person said the chain was stretched. Since it didn't cost much I had him change it even though I was suspicious about his assessment. Now I just measure it with a tape measure. If I get 12 1/16" (.5%) between I believe 24 links I might change it. I measured the replacement chain 1,000 km later and it measures exactly 12", as I expected.
I'm not fanatical about keeping my chain clean. I wipe it down with a paper towel and short bristle brush about every 200 - 300 km and re lube it with WD40 "Wet Bike Chain Lube".
Even if its not elongated to 0.5% the rollers might still be worn. Some chain gauges includes the roller wear, some not. That may be the reason the shop recommends replacing the chain, even if you ruler says no. Imo its debatable if roller wear should be included, but from my experience a chain that is not yet elongated to 0.5%, but has a lot of miles on it, tend to ride notably less smooth than a new one.