Lisa Foster ........offers the BEST idea yet!
‘Here is my solution to skirts that flip up: find an elastic band that fits around your thigh (I use a headband, but you could use a garter if you’re feeling VERY diva), then attach a safety pin to it, and slip it on 6 inches or so above your knee. When you get on your bike, fasten that safety pin to the inside of your skirt. The skirt stays down! If you’re feeling very demure, you could do this on both legs, but one usually does the trick.’