good tips all around, and I would add - have a pen ready. And maybe a helpful friend. As soon as you remove yourself from whatever you're sitting on, feel around and pinpoint the deepest part of the probably rather large indentations you've made, and mark them with a pen. When I did this with paper on a yoga mat the indentations would disappear within seconds and be impossible to mark off. I also repeated the measurements several times, and reckoned an average.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett