Hmm well, maybe an electro magnet with a spring assist? If you get the distance between the points of contact the spring acts against you can make it hair trigger(don't or it will flip whenever you twitch) but get it reasonable and put in a rare earth magnet and an electromagnet. After the initial lift by the magnet the spring will catch and carry it up. OH!!! And make it so at the top of the ride the spring is no longer in play and just moment carries it up, maybe a dip to hold it in place! Then if you flip your head it ought to drop and the moment might carry it past the spring, the powered off electromagnet will attract the rare earth magnet sealing it back down.