what I find disconcerting is that even when i follow the instruction sheet for 2 different bikes I have significantly different avrg and max speeds. could the 2 bikes actually be that different? one is 27 1 1/4 wheel and tire, the other has 700 x 28c wheel and tire. I totally have to do the rollout again this year, but I remember it being confusign to measure in metric and make a 4 digit factor out of a 3 digit measurement ...