I've spent a lot of time experimenting with different options. These are the conclusions I've come to:
* I can either ride well or shoot well, but if I try to do both together it will likely result in total fail.
* Speed and agility are my greatest advantages.
* If I maintain a gap in front of me - which I'm in total control of - there's not really any traffic situation that I can't move forward in on a bike, short of an evacuation scenario gone bad. That cannot be said for mean spirits in anything larger. Bonus points for riding near the break-down lane.
* Gripping a handgun with motorcycle gloves is sub-optimal. Working the trigger is even worse.
* Motorcycle gun-fights are soooooooooooo south of the border.
I carried in a tank bag for a while. That worked OK, except that when you were most likely to need your firearm (off the bike), it was least accessible. Plus you absolutely had to take it with you every time you dismounted, no matter what, which doesn't sound like that big a deal, but really became a pain after a while.
Definitely don't want to wear it SOB (small of back). Landing on that in the event of an off wouldn't be spine-friendly.
In the end, I ended up just carrying like normal (IWB, ~4:00). It's not in my way as an appendix or anything forward of 3:00 would be. Can I use it to defend myself when on the motorcycle? Not at all. But it will be with me once I've got those gloves & helmet off, which is what I deem most important.
OWB 3-4:00 would work just as well too, and offer you the potential to go all Mad Max if you so desire. But I greatly prefer to carry concealed, so there's that. I have a friend that swears by open carry, claiming most people give him a wider berth. Always a good thing on 2 wheels, but also potentially a distraction.
After commuting exclusively by motorcycle for years, I've had a handful of potentially life-altering encounters with colorful folks on the roadways. People's inner reptilian really comes out when they pilot a machine bigger than yours. In every single case, the problem was quickly resolved with the judicious application of throttle, brake, and/or handlebar input... usually resulting in a rapidly-disappearing dot of high-blood-pressure in the vibration-fogged haze of my rear view mirror.