Currently, I'm using a front light rated at 35 lux on my bike. This is just about bright enough for my riding, but I'd like something a bit brighter. However, most of the lights which might be brighter are rated in lumens, rather than lux.
I'm a physicist by training, so I know the difference between 1 lux and 1 lumen and that you can't compare them directly - but that doesn't help me as I do need to compare them somehow. Is there any rule of thumb or something that I can use to work out which lights are actually brighter than my current light, or does the beam pattern of lights vary too much for this to be a sensible comparision in any way at all?