Here is the latest chart showing the rides I have done - distance in miles on the vertical axis against date on the horizontal. The trendline is still good.
The first hour was much more fun than the second because of Jason Glasgow's presence. Jason is a veteran cyclist and a veteran of the Hazon Israel ride. He swung by early and off we went. I could see his pedal cadence was faster than mine in most situations, and so I decided I was using too high a gear. I started aiming for a faster cadence, and lower gear. The rest of the ride seemed to go well with this adjustment. Jason had to get back in time for his carpool, and so I did the second half of the ride alone.
Although much, much better, the 5th gear problem did recur. Jason asked, "did they give you a new cassette (set of gears)?" I think they did not, but just fixed what I had. I may need to go back again on this one.
Based on my background reading on hydration and nutrition I made a point of eating a nutrition bar halfway through the ride, and coming back and eating a good breakfast. Hopefully this will help my body build up strength (rather than feel lousy).