My knee warmers don't creep down unless I wear my shorty shorts that just barely overlap, but they have a good gripper (i.e. a slightly uncomfortable gripper, in the long run) and I hike up the bottom end so that they're "pre-bent", if that makes any sense. The lower hem is then just underneath my knee, nowhere near my calf. That accomodates all my knee-bending when biking without going south.
My long leg warmers however are a bit useless. They're comfy as such, but they're pretty obviously not cut for my thigh/calf ratio. (Aren't women often built differently from men in this area?) The upper part is too long, so that when fitted over the knee like they're supposed to I have the upper hem up near my crotch. Yuck to grippers on upper thigh. Worse, the lower half is too short, so that they flutter in the breeze way above my ankle. Always have to dig out long socks for those, hate that.
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