Sorry to say I'm unimpressed with the generic light that @
VegasTriker recommended. It didn't come charged. I charged it but there was no charge indicator light. I still haven't figured out how to cycle through the modes. Then it discharged and wouldn't take a charge. Aha I just discovered that it does have a charge indicator light. But worse, the USB plug has to be pushed in just right, because the contacts come undone even when the plug is in. Also, the construction is unimpressive.
I do understand that this was inexpensive and not built to impress. Maybe these days I prefer well made things. I do sometimes enjoy cheap things for how well they serve, given their price, but too many bike lights have disappointed.
I'll try this again. I mounted on the side of my left crank so that it points forward for part of the cycle and back for part of the cycle. Not sure if that's a good idea, but I have received compliments on the light in my rear wheel.