I know a lot of people here use the amber strobe light from All Electronics. I always thought it was a good idea -- a flashing yellow is the universal sign of a slow vehicle, a lot of states require vehicles (other than bicycles) that travel less than 25 mph to have a flashing yellow light at night, the DOT recommends it for slow vehicles -- so motorists should recognize that there is a slow vehicle ahead of them.
But it turns out that Virginia, a neighboring state where I occasionally ride, strictly regulates the use of flashing amber, and bicycles are not one of the permitted uses. Here's the code cite, which I stumbled over today while looking for something else: http://leg1.state.va.us/cgi-bin/legp...+cod+46.2-1025
It also appears that cyclists may not use flashing red lights, which are reserved for emergency vehicles.
I don't quite understand why they care about flashing yellow. Any thoughts?
There is a related section, 46.2-1081, which deals with the slow-moving vehicle emblem, the triangle, which is the daytime analog. Basically, all slow vehicles must have one, only slow vehicles may have one, and bicyclists get the choice to have one or not. I would think yellow lights would work the same way.