waterrockets 

Hey, I bought a used ebay bike with Ultegra R8000 disc 11-spd group. When it arrived, I noticed that the front shifter, going from from small ring to big ring was catching before moving far enough to shift. On a second try, I am able to shift it with a "snap" that feels like breaking a very thin zip tie. It doesn't seem to damage anything, and does this exactly the same every time. I noticed that the derailleur was under tensioned (cable slack in small ring).

I installed a new cable (old one looked fine coming out), went through entire Shimano process with limit screws, cable routing, cable tension, etc. It would NOT shift to the big ring -- that catch just sticks. If I under-tension it, it will shift with the catch on the first try, and success with a snap on the second try. So I'm exactly where I started, but with a new cable. Also, the shifter will move smoothly through the shift if I move the derailleur by hand (limiting the tension on the cable).

So, it appears that the shifter needs to move a certain distance before it hits tension, or it won't shift. I'm guessing there's a strand of old cable inside it or something, but I didn't see any obvious access panels I could remove to investigate, and the cable routing through the shifter is brief and doesn't appear to be near the ratchet system.

Any thoughts on working this problem, or is it time for a new shifter?

Thanks!