Random stuff I know... Randomly...
Two men should not ride a motorcycle together.
If me and my last surviving buddy were in the middle of the zombie apocalypse and we came across a motorcycle and it was our only way to escape a zombie horde, I would tell him to ride the motorcycle alone and find a car and come back and get me before I hugged up with him on the back of a motorcycle. If he could find a helicopter, even better.
Allowances can be made if the second rider on the motorcycle is your son.
Same thing goes for two guys on a horse.