Thats one sweet freakin' ride. Looks like you have the 1in roller on there. Great for cruising. Looks like you get really good friction engagement with those wide flat tires.
It's got a 1 1/8' roller and tops out at 27 mph. I got the bike off craigslist and the staton kit off Brad on the site. It weighs in at 29lbs bike only and she even folds up unfortunatly on the motor side. http://www.hummerbikes.com/ There's a couple of photos on Staton gallery of the bike with chain drives.