That no lockring trick seems like it'd be fine, as someone else said, until you need to backpedal. There isn't too much backpedalling going on on the track, so tha'd be a place for such a trick, but is a bike w/out a track hub + lockring track legal? Maybe in Italy where cycling in general and track in particular are more popular it's okay for a po' man to rig out his bike for some track action that way.