Personally I find that on a road bike, an self contained unit with no external battery, is a massive bonus. I picked up a 2nd hand Exposure Toro for not much money for that very purpose. Doesn’t need stupid amounts of lumens on a road bike either, a narrower beam pattern will make more of the available firepower.
For offroad use, a much broader beam pattern is ideal. I’m much happier strapping a separate battery to my mountain bike frame (for some reason, might be cos it’s ally versus carbon). Got a Troutie Lumen liberator which is the mutts nuts, but you can spend a lot less for nearly as good performance.
Alternatively, you could just buy a couple of those Cree XML torches and strap em to your bars Heath Robinson style…