Are you shifting them simultaneously? Because that's what I usually do and I've never had problems with spinning. I can dump three gears on the back with three quick clicks of the shifter, though I do ease up on the pedal for a fraction of a second to allow for this to happen smoothly. During this split second my legs are spinning at the rate that I think I ought to be in once the gears engage, and once they do engage you are right there. Sounds like a lot, but it's really only a fraction of a second for it to happen. It does take some practice. It doesn't matter if it's 53/39, 52/36, 50/34, 46/36, 50/39/28...I have all of these.