Do you use the bow/gun rack?
Right, I'm in the same boat. I do not mount my weapon to the bike... too much vibration and chances for things to go wrong... remember, it's not a 4wheeler... you can and will eventually take a plunge/nose dive once you get too comfortable/complacent
My weapon is always over my neck and shoulder... probably not the safest way... but I'm not beating up the gun that way.
Also, when I'm scouting, I'm topping that thing out and blasting from point a to point b... but when I'm on my way to a hunt, I'm rarely going even 10mph... I'm just barely creeping along to keep it quiet and keep my mind in the slow and methodical game... it's also good to go slow past other hunters or others watching.... because they WILL complain... and that doesn't help us keep these options
My first spill was after a hunt, I was deep in the back of the wma (about 4 miles from my truck), I had less than an hour to check out at check station (30 minute drive once I got to my truck) and I was loaded down with too much other gear (big ole 180 summit). I was hauling through about one foot deep in muddy tractor ruts and hit a stump or rock... I was probably going about 17mph or so and all my crrap went everywhere... everything was underwater... it was terrible. I don't haul asss around anymore with gear... even if I have it secured tight.
Basically I havent found a "perfect" way to carry my weapons. I know I will be switching to pistols for muzzleloader and gun seasons, but for now the bow gets put on my back.