Here's the latest solution to the seatpost problem, a new carbon post with a larger clamp surface. All carbon clamp parts (aside from the fasteners), and they were slipping on a brief test ride last night. So, complete disassembly and cleaning of the saddle rails and clamp, and then liberal application of carbon paste.
Although (in theory) only the rear bolt needs to be tightened, I decided to torque down the obscured bolt by cutting down the working end of a spare 5mm hex key and working it into place to tighten. All torqued down now. Another test ride this evening, and this should (could? might?) work.
