I'm sure the list would love the benefit of your insights on why the P/R frame is suitable for 650B but not 650A. Perhaps you could explain the major geometrical parameters of the P/R that were optimized for the 650B rim size, standing, as it does, 3mm shorter than 650A.
Best,
tcs
Geez, did the Easter Bunny not bring you enough chocolate today?
Well, the whole point of the P/R is that it's created in the tradition of French 650B bikes and is intended to take advantage of that wheel size and tire choice. Could you run 650A wheels? Given the grumblings on the KOG list about canti posts being a shade too high, perhaps that might be a good solution. I happen to have one, and am very happy with 650B wheels on mine.
Neal