Well, Garmin does have one for a motorcycle…not necessarily a sport bike, though. It even has a little motorcycle icon instead of a car. I know there are motorcycle mounts as well, but I can’t say for sure as to where they mount.
maybe i saw it here or on another site im not sure, but i saw a video of a guy that custom modded a otterbox for a iphone to fit inside a go pro mount and stuck that to his bike. he put his on his windscreen and took it to 120mph and no issues phone stayed right in place. I might try something like this for the otterbox for my Droid. Mobile GPS right there.