Electric MonoTracer At Brno, 2011
The X-prize-winning electric MonoTracer with 150kW (201bhp) AC Propulsion motor, with side cover off and batteries exposed, at Brno for the annual training in 2011. Note the extra-wide rear wheel. PNB
Photo: © Paul Blezard
Rear wheel
It also looks to be a smaller diameter, with a very low profile tyre.
Very low profile, very wide!
There's a closer look of that fat rear wheel here Colin. It's certainly very low profile and very wide, but I doubt very much whether it's smaller than 17in in diameter. http://www.bikeweb.com/node/2219