Maybe a Planet Bike 2 watt, 1 watt is a be seen light 2 AA rechargables or what ever. 2 w is recent.

Other than that I have an older Nightrider Sport battery pack on cord 5 D cells upgrade pack of D NiMH
and recharger mens they get recharged in place , rather than come out and be recharged as before.

though a LED Upgrade on the AA Maglight seems adequate, as a be seen light.
2 fish rubber block velcros the lamp to the handlebar.
handlebar,