"Given the conditions of the flat, a trip to Bike Gallery to discuss brake adjustment/modification options should be considered. And I guess I'll be getting to try out those Soma Xpress tires somewhat sooner than I planned."
The flat occurred because the drive-side rear brake rubbed on the tire. The brake could not be adjusted to not rub on the tire. I didn't notice it until a month ago, when I was giving Sweetpea a good clean. It didn't seem to be a problem. At least until yesterday, a few miles from home.
The brakes are Tektro R556, purchased on-line, on sale in the fall of 2008. Perhaps there was a reason they were on sale.
I couldn't decide what was up - I've got supposedly the Very Same Brakes on Bleriot (also a 650B bike), and there is still room for adjustment on that side. The Silvers are the Rivendell-branded Tektro brake. I bought the Silvers in winter 2007.
Now that I knew what was going on... ack. Big ride next month, didn't need a tire flatting because of this. I understand there are many other reasons a tire will flat out there in eastern Washington, and indeed, a friend riding a 400k out there yesterday had a ton of flats, as did the folks she was riding with. They had a flat-patching party in the Safeway in the middle of the night to repair all their tubes. No, don't need more opportunities to get a flat tire, especially with the amount of wrestling it takes to get tires off the Aerohead rims.
Took the bike into Bike Gallery this morning, and had a long conference with Mechanic Tim. (for the record, I prefer working with Mechanic Tim, Mechanic Mark, or Mechanic Michael. I am sure the other mechanics are competent, but these guys completely understand what my bikes have to put up with)
We stared at it for a good long while. He thought the brake arm might be a bit short. I did, too, but a cursory once over with a precision measuring instrument didn't seem to indicate that. He suggested I try the rear brake from Bleriot, to determine once and for all if it was the brake.
Went home, hauled out the repair stand, cable and housing cutter, third hand, allen wrenches, little bag of ferrules and crimps, some tunes and a cup of coffee.
Pulled both brakes, and compared them side by side. The Tektro did look shorter. Hmm.
Put the Silver on the Sweetpea, dropped the brake pad to the bottom of the notch. Nothing but rim. Relief! Got everything adusted, put a new crimp on the cable, one down.
Then, put the Tektro on Bleriot. Nothing but rim; no adjustment needed (good, because there was no more adjustment to be had). Finished that up.
Called Mechanic Tim to let him know all was good.
Now just waiting for the new tires to arrive.