Regarding the OP's question - I think that if you're interested in the motorcycle, then the answer is measured in miles. If you're interested in the rider, then the answer is measured in hours. I pay more attention to hours than miles because I adhere to the idea that it's the archer, not the arrow that makes the difference.
'Thanks to the interstate highway system, it is now possible to travel across the country from coast to coast without seeing anything.'
- Charles Kuralt, On the Road