Nice thread. Caused me to do some research, where I stumbled onto this:
Greg Fisher - Quadracycle
Not to mention the links posted by markhr
shameless POWERCRANK plug
Recommended reading for all cyclists - Cyclecraft - Effective Cycling
Condor Cycles - quite possibly the best bike shop in London
Don't run red lights, wear a helmet, use hand signals, get some cycle lights(front and rear) and, FFS, don't run red lights!
Furthermore, who'd want to pedal it up the fireroad to begin with? Heck, who'd want to figure out how to transport it to the fireroad?
I suspect these quads are good for getting attention on internet forums and taking up space in the garage. I'll stick with my old hardtail for now.