This is a short post, named so that people find it when searching…I’ve seen a lot of people on the interwebz asking if it is possible to use a Quarq powercrank with Shimano 11 speed parts. The answer: yes.
I’m running a stock 2013 Quarq SRAM Red 53/39 crank with the original chainrings, set up with Shimano Ultegra Di2 front/rear derailleurs, Shimano Ultegra 6800 11 speed, 11-25 cassette, and Shimano Ultegra 6800 chain. I did not have to do anything fancy, did not have to change the chainrings, did not have any issues. Shifting is positive and perfect. No issues. The chain looks like it was meant to be on the chainring. I’d say that it’s 100% compatible, based upon actual, been there-rode that experience.