I'm pretty new to the sport and I've been wondering about air pressure lately. The articles that I've read seem to say that you want to run as low a pressure as possible without flatting to go fast, which seems counter-intuitive for low rolling resistance. I know on the road you want as high a pressure as possible to reduce rolling resistance. I've been running around 30psi (or a little lower) to try to get better traction, but I'm wondering if I'm putting more effort into pedaling to overcome the low pressure. Any thoughts?