As one of the other posters already alluded to, there is no need to mess with something like a motor vehicle sealed beam headlight. Just go to any local bike shop and tell the people there you want a lamp for riding in the day. What you want is something that will flash with output in the 100-200 range ( although this is not for use for daytime paved trail use, road only ). Point being made; a bright flashing light will get you seen.during the day faster than any type of steady light. If you've ever seen anyone using a flashing light in the day you know this is true. At dusk or night the 100 or 200 would be too bright so this is only for day. No need to make the issue more of a problem than necessary by building something designed for a car. There are already plenty of bike light products available for bike use that will work very well whether you want a front light or a back light. If you are insisting on something wide and big there are already several types of bike lights ( both front and rear ) that utilize wide COB panel LED's. You just have to do some searching. Ebay and Amazon are a good place to start.
Last edited by 01 CAt Man Do; 08-08-18 at 11:19 AM.