TECHNICAL PROBLEMS FURTHERED...

Turns out it was the rim on my rear wheel splitting in 2... cracks were spreading laterally from the spoke eyelets. I took the wheel back to Bierspool Cycles, where I bought it around a year ago. They sent it back to Madison, the suppliers, but they haven't returned it yet. Bierspool did "lend" me a wheel, with which to do my Big Ride (more later); the wheel they "lent" me was the old wheel I'd left with them when I'd bought the current set. The bearings had completely gone. They'd since put a new axle and bearings in, but as predicted, there was a lot of wear on the hub races, and the axle worked itself loose during the second day of riding. It got me there and back, which is what mattered.