I actually took up about an inch or so in the opening of the top of my knee warmers and stitched them together to reduce their size. They just don't make stuff for long skinny legs. Reducing the size helped some but for long rides I haven't found anything that works perfectly. That's why I recently bought another pair of knickers.
My darn tights seemed to have stretched and are sagging.......guess I'm either going to have to get another pair or bring out the suspenders.