I'm with those who don't really foresee drawing while riding (though you never know when you'll need to). In town, I can out accelerate or out maneuver most vehicles on the road, even on my heavy and underpowered 800cc Suzuki Boulevard. Of course, on the highway, I'm not so well off. My thoughts in asking this are more for when I get off the bike or when stopped at an intersection. When I get off the bike or if accosted when stopped, and I'm in a CCW state, I'd like to be able to access my handgun. When in MD, and not riding to work, I carry a knife in (or clipped to) my right front pocket (I'm a teacher, bringing a knife to work would be illegal).
As for what/how I ride, I have a Suzuki Boulevard C50SE with bags and a shield. For non-motorcycle types, it is a cruiser, a style popularized by Harley. I sit upright, not bent over like on a sportbike. About 90% of the time I wear a jacket when riding (either leather or mesh depending upon temperatures).
I still haven't decided what I'm going to go with on the bike, other than wanting some kind of retention. When not on the bike, I carry mostly IWB or pocket, sometimes on the belt, and always strong side. Usually just behind the strong side hip (though I've been thinking about moving to appendix carry or maybe 2:00 with my IWB to more closely mimic the draw when carrying a pocket gun since I often do so). Maybe a low riding or tuckable IWB with a short barreled pistol to aid in concealment when riding and to mimic as closely to my usual carry style may be best (with the only change being the retention system of the MC holster).
Anyway, we still have several months until the return of riding season around here (it really just ended), and it likely won't be warm enough to take any long trips on it until March or April, so I have some time to think about it.