A strip of 3/4" double-sided velcro tape can be used the same way as a rubber band, or can be used to hold the front brake lever down. The later doesn't prevent wheel flop but does prevent rotation, which is the problem when it comes to tip overs from a resting state against a pole, tree, etc. Wrap it around your stem or head tube to keep it out of the way but handy when not in use.