I' ve used them on my girlfriends bike. But they fell of the bike on a bumpy road in Sweden because the metal holder that is fitted to the light to fit them on your bike broke.

Besides that they have 3 built in operation modes: high Beam, low Beam, Flashing. To choose a mode you have to push the switch every time. It isn't possible to just use one mode every time you use your bike. You can modify this. There must be a topic about that on this site.

I now use these lights on our bikes:

http://www.dx.com/p/10w-cree-xml-t6-...6#.V9GbZpiLQ1I