I tried to, once, when my bike was an ss. I was going to my folks house and ended up walking most of the way up. Coming back down was alot of fun. My computer showed 60 kms as a top speed before I had to slow down for a Honda civic in front of me. This was on mount Albion road if you are familiar with Hamilton at all.

Actually, now that I think of it, a friend of mine, myself and my cousin rode up the rail trail on our mountain bikes a few years ago. We rode along Concession street and took one of the main arteries down the mountain. We were riding some fairly respectable free ride rigs(two Konas and a Devinci Hucker) with knobby tires down a four lane, two direction road. If you have ever heard a four wheel drive with big tires on the highway, thats what this sounded like. It was lots of fun, but scary too.