I pull single speed cruisers on my mountain bike-turned-heavy duty hauler. It has a Surly rack on the back. I just place the bikes so they are facing away from each other, then pull up on the front wheel of the cruiser like I was popping a wheelie, but I keep going until the cruiser is upside down and the handlebars rest on the rack. Then I just bungee cord the handlebars to the rack real well and off I go. It won't work if you have fenders on the bike being towed, but a MTB should be OK.