one of the things contributing to the problem was that the seat post mast was occupying a lot of real estate on the saddle rails. I went to the shop today, and found a 31.6 (yes it's a PITA 31.6 diameter, not the typical 27.2) with a mast that's much smaller, with the typical 25mm setback. Right now, I am only 5-8 mm away from the measurement of my fore/aft on the road bikes, with the brooks slid all the way back. I think that's good enough.. I hate to go through the trouble to find something that nobody uses, and costs a hundred dollars..