But then, there is the bike. This year I was determined to give it a try, once the winter broke. I wasn't completely confident. The muscles used in riding a bicycle are different from those used in walking, and they hadn't been used in a long time. There remains substantial numbness in the lower half of my body, so I wasn't exactly sure how well I would be able to control the vehicle. And once one's feet have left the ground, there isn't a lot of room for error. A fall would of course be fairly calamitous.
The transmission on my bike is 24-speed, so it can be cranked down to a point where, on a level surface, very little force (but a lot of pedaling) is required to achieve forward progress. I assumed that I should begin with this configuration, not knowing how much force I would be able to apply. I wasn't even completely certain that I could remain balanced on the thing. But as it turned out, things went better even than I was hoping. I was able to advance the gearing (but still considerable below the old normal) and ride up and down the street some way a couple of times. I was very happy with the results of this first attempt. I certainly could feel the fact that I was waking up muscles that had been asleep for a long time.
Since then, I have made a lot of progress on this. I can ride several miles, negotiating steep hills, just as before, albeit at a much slower pace. I can feel my strength and stamina improving. I'm not sure it will ever be the same as it was, but that seems hardly to matter. For now, I can just enjoy the ride.