I think I may be cursed. I have been running Ultegra 6700 on my two road bikes for the past decade. About every 2000-2500 miles, the rear shifting gets fiddly and it won't shift to the smaller 2 or 3 cogs in back, and the cause is ALWAYS a frayed shifter cable. I had thought initially I had a "defective" shifter but when I got my Roubaix it had the same problem. I even replaced the shifters when they were worn, a few years back, but the problem persists.
Fast forward to 2022, I recently put on a full Ultegra R8000 groupset on my main road bike. It works like a dream. I have about 2200 miles on it, and today the SAME THING happened.
I am guessing at this point it's not necessarily a design defect from Shimano, but either I am shifting way more than a typical user, or possibly somehow I am not installing the cable correctly. I always use Shimano parts and am pretty sure I am doing everything right.
Other than jump to electronic shifting, any suggestions or comments??
See pic below of today's cable once I extricated it.
