The rest of the ride was quite uneventful. I kept thinking about what happened earlier. I was sure the drivetrain was set up perfectly because I triple checked everything - the hanger, the chain length, the b-screw, the limits. And yet...something was obviously wrong. Oh well, something for the LBS to figure out. I went past the Byland Abbey just as the sun was disappearing behind the horizon and that was a beautiful sight. By the time I returned to Northallerton around 5pm it was completely dark.
Here are the Strava activites for the day:
P.S.I visited the LBS in a few days. The mech guy said that the cause of all my troubles was a stiff link. I put on a new chain and now the drivetrain is purring like a kitten.