Nod, slight finger lift off the bars if warranted, and usually a smile. I don't see many commuters on my ride so I'm not exactly in danger of dislocating a wrist from waving. But I like to at least acknowledge a fellow utahrd on a bike. I don't do full kit though. I don't even own a kit. But if I did, I would never wave or acknowledge anyone just because. But the chances of me owning full kit is pretty slim. Like 0% unless someone gave me one. Then I'd refuse to wear it on principle. I'm not going to pretend to be that kind of biker when I'm not one. I mean, who wants to be "that guy". The guy in full kit on the MUP.

But seriously though, I seem to get a 50% response rate from kit dudes/dudettes. Usually the weekenders. Conversely, I get 0% from the x-mart non-white commuters. How rude, eh? (I"m not white either, just sayin.)