Hugh-
Wasn't I just telling you that the reason I hadn't gotten back on the bike yet was that I was scared of falling (being on warfarin and all)? And now you've gone and done it.
So... I guess you'll lead the pack in taking up one-armed rowing, right?
About 6 weeks after my surgery, I was outside puttering in the yard, trying to feel productive. I turned around and tripped over a concrete curb that I should have remembered was there... falling forward, I instinctively put out both hands. I didn't break anything, but the jolt to my still-recovering shoulders and sternum - OW! I thought I was going to pass out for a second there. I think I sat there on my knees for about five minutes trying to shake it off before I could stand up. I've done the failed track-stand fall, too, and know how much that can hurt. The last time I pulled that stunt I was smart enough (how can anyone who forgets to unclip be smart?) to not put my arm out- I just let my shoulder take the hit and tried to roll (not easy with a bike glued to your shoes).
Best wishes for a speedy recovery - stock up on that 8 hour Tylenol...