Originally Posted by
CommuterRun
I suggest the 1100 for your seatpost and a 500 for what I think you might be looking for in a helmet light.
Or the Planet Bike BRT-5, which is far brighter than Cateye's LD500 and is also designed to clip onto stuff without having a super-long clip that'll gouge the rider's neck. And the Mars 4.0 struck me as having an exceptionally large hotspot, it's worth looking at too.