Originally Posted by Trsnrtr

A few years back, I decided that I wanted to add a bigger cassette to my tandem so I bought a Wolf link and a bigger cassette and installed it but the dang thing would never shift right so I decided the old derailleur looked worn out and bought a new derailleur.. The thing still wouldn't shift properly so I reinstalled all of the old stuff which worked flawlessly and gave up. Some time later, I was showing a friend my tandem and mentioned the problems i had had with my new 11 speed Ultegra derailleur and 11 speed Ultegra cassette. It only took him a couple seconds to point out that I had a 10 speed drive train including 10 speed shifters.

Duh...