Sorry, by double shift I do mean shifting both the front and rear at the same time (to the smaller ring and a smaller cogthe XTR 11-36 is spaced to make these shifts similar to simply shifting to the next larger rear cog). I'm using Ultegra STI 6770 shifters, the FD6770 where I replaced the actuater screw to push the shift farther outboard (with the stock screw the motor won't reach out far enough but the design of the pivot points of the derailure cage itself could reach), and a modified RD 6770 from K-Edge. The shifts to the larger ring are fine, great in fact, but on occasion without the double shift (front and rear) the chain won't drop to the smaller. I'm currently running Ultegra 53/39 rings (and the 36-11 cassette).