Yup, I figured the only way I'd get the thing to start moving w/me aboard was to have some gearing like a bicycle. I figured on multiple gears and derailleurs on the forward and intermediate sprockets. I'm still unsure as to whether the rear end should be independant suspension or just 1 axle w/2 tires. Coming off the original concept of a track to 2 close tires seems like a natural progression but with soft, low pressures I get worried about the roll stability (tippiness) at the rear end. So going with wider spacing of the wheels would mean independant suspension and dual chains (1 to each wheel). The wheels should have freewheeling capability just like a bike does. As to brakes ... hmmm ... guess I should have some just in case it does get into motion somehow.
Somebody had suggested mountain bike wheels and tires in place of the knobbies as mentioned earlier. Still not sure how much grip I need or can get from either type of tire. Then again I guess I could add "studs" like an ice racer does. Haven't figured out whether the steering should be cable or some salvaged boat hydraulics. I like the latter idea but I'm thinking of FLL levels of frugality here.
Of course the seats have to slide fore/aft to fit different people to the fixed pedal cranks.
SC - yes still on track to take a fall this fall. Got to get my fun stuff done now while I still have a
life ... ouch ! stop !! aaargh ....