Originally Posted by
Racing Dan
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.
Good point, I never thought of that. I did have some trouble with the chain not fully engaging the gears when I got the bike. I may have turned the adjuster on the shifter and messed it up. I may have damaged the chain trying to get it to engage. I recently tried to adjust the front and rear derailleur's so now this Shimano Altus triple chain ring is shifting OK if I'm careful, and the rear is not jumping between gears any more.