You should definitely check out The Cygolite Expilion lights. I have the 350 lumen one and its insanely bright with multiple levels of adjustment, you can swap the battery with extras on longer rides, and water resistant.
http://www.amazon.com/gp/product/B00...ls_o01_s00_i00 Also to swap the battery you just twist (half turn), pull out the battery then insert the new one and twist that one in.
Run times:
- Two hours on "boost"
- Three hours on high
- Six hours on medium
- 13.5 hours on low
- 24 hours on flash
