I have a Specialized Echelon that I'm currently using (it was free- won a LG time trial helmet from LBS but was allowed to exchange). I've tried mounting my cheap light that's powered by 3xAAA using rubber bands, but either I can't get the aim right or it flops around too much. And the zip tie trick didn't work for me either .

Also, since I'm a bike/bus commuter, I only wear the helmet while on the bike. The helmet either goes in a backpack or dangles from the top haul loop. Not sure I'd trust a lockblock to hold a light when it's flopping around on the outside of a bag like that, but maybe the mount by itself (with the light removed) would be okay?