Anyone ever try putting the clip-in bicycle pedal cleats on the bottom of a walking boot. You know, the giant black velcro things you get to hobble around in after fun adventures?
i didn't think this is what "it" constituted... also, would you want to go for a ride with your careening ball of metal as it rolls, and flips, and colors, and tells stories?
i've seen people put sticky rockclimbing shoe rubber on those boots, but never cycling cleats. 'twould be easy to do, but prolly a really bad idea. the boot is really wide and in order to mount a cleat so that the boot would clear the chainstays and crankarms, you'd have to have your foot way outboard of it's normal and symmetrical pedalling location. a very good way to end up with some evil muscle/tendon/cartilage overuse injuries in addition to inducing bizarre asymmetries in in the rest of your body from sitting sidways on the bike...
When I had my ankle surgery, i just converted that side of the pedal bike to a toe-clip style pedal and had a larger strap put on there. I was 'lucky' in that the cast was on the non-drive train side, so I didn't have to worry about clearance as much. As the "TON" says though, the ergonomics will be off and potentially cause damage to your knee; or damage more important bits..
If it was anything like my experience in one of those boots, I'd imagine clipping in and out with any kind of twisting motion couldn't be good either. I did what others suggested and put a flat pedal on that side for a little while.
Are you speaking of putting these on a motorcycle? if so I saw it done on a paraplegic last year at Njmp.
Most of mine was road biking, but the mtn biking will work if you are going on clearcut trails. Not sure if your issue is ankle or tib/fib, but if it's ankle, be careful about lots of bumps. Just because your foot is in the boot/cast doesn't mean that it won't bend and absorb shock. Hit the road for a while, or make sure they are jeep trails with no bumps.
Lawn Dart beat me to it. If you have a walking boot/cast, twisting motions are probably not recommmended. There is a reason they are restricting motion with the boot. Also, would the jarring and such be the best for an area that needs healing? Active rehab is usually always good, but I dont think your doctors envisioned mountain biking as part of that.