I found an urban mountain bike path the other day. I must admit, that despite my admiration for phat bikes like the Trek Fuel, I'm but a resident, and I have to tackle mtb trails on my, ahem, 'fitness hybrid' with l'il skinny knobby tires. The picture here shows what a real trail does to a bike like that. I got faster as soon as I lost that thing. It was still stuck to the crank, though, like clinging to life, after it hit the tree. Gotta love a real workout, not one in the A/C with headphones and a little TV on the front of the elliptical.