Hey yss,
I have about 30 degrees flexion in my left leg. Even the folks closest to me don't seem to be able to imagine how 'I managed to let that happen' or the challenges it creates. My understanding is that one needs about 90 degrees of knee flexion in order to ride a normal bike off the rack. While a shortened crank can make up for some of the difference, they don't work for me and wouldn't work even if the pedal was effectively fixed to the cartridge at zero crank length. As far as I can tell, after discussing it with countless medical professionals and scouring the internet for adaptive devices, I'm left with few options for riding a bicycle. I'm not sure if the same is true for you but I thought I'd offer a few suggestions that might be helpful in your quest.
First of all, you might want to check with bike shops in your area for those that have the proper equipment to assess your "riding style". The better shops have computerized equipment that, if anything, can determine if you if a shortened crank will work for you and make appropriate recommendations. A true enthusiast will be more than happy to accommodate your particular needs towards the goal of seeing you ride again. Secondly, there are hand-crank bikes, trikes and quads available in both upright and recumbent configurations. Technology continues to make these bikes increasingly viable options. Thirdly, there are electric bikes and electric assist bikes that can increase your riding range, alleviate some of the doubts and fears you may have, and most importantly get you out and get you moving. I find that I can overcome the worries of pain for the sake of doing something that's enjoyableand I tend to recover much more quickly from the pain itself that resulted from the doing. Give me an activity that includes a "woohooo! look at me now!" amd I'm there. Just a thought based on my own experiences with the cycles of depression and feelings of being defeated. Finally, I came across this website a short time ago:
http://kneepainrehab.com/. I've been hesitant to purchase the articulating crank mostly because I've only found it available from the inventor who is in Great Britain and the cost with shipping comes to over $500 shipped. I lost my job in December so i have to take particular care before I make that kind of purchase. I think that some combination of all of these things I've mentioned is what will work for me. I just need to congeal my thoughts into action.
I hope I've offered something useful to you.
Regards,
Tom