My understanding is that 11 speed spacing is slightly narrower than the 10 speed spacing. In such a case you might have some problems to begin with. But in any case, the 10 speed shifter will render your 11 speed RD to a 10 speed RD...which kind of defeats the purpose. If you are referring to running a 10 speed setup with a the m7000 RD...It might work, but I can't imagine that you will have the same smooth shifting as a normal 10x combo. Shimano 10x: 36t Cassette: 11-13-15-17-19-21-24-28-32-36T Shimano 11x: 42t Cassette: 11-13-15-17-19-21-24-28-32-37-42T So your bottom range is similar, but again, spacing as well as offset differences might complicate matters. The question still remains why!?... Okay now I see why... One suggestion is to check yourself? Using your M8000 RD... But it's a lot of time & effort and you'll probably have to redial to RD back on your own setup. My final suggestion is just to take the bite, buy an upgrade and sell off the old parts. Throw in some Sunrace components to save cash. It is not that expensive anymore (yet..?).
