I can relate to Sheldon's leg problems as we share similar concerns.
Both concerns take function from our legs and , pretty much, end
our BIcycling days. All that is left for us is TRIcycles which is OK
in my case.

I can also tell you that there is a level of personal sorrow in loosing the
full use of one's legs (or any other body part for that matter). One learns
quickly to adpt and move one. Like Sheldon I too have to use a Rollator
when I walk alot in place of my ever present cane. But that's Ok 'cause
I can still get around and have not been forced into a wheelchair......yet.

The important thing for folk's like Sheldon and me (along with many others)
IS TO NEVER GIVE UP THE FIGHT TO KEEP ON CYCLING.