I use a Blackburn Flea on my fixie because the shape of the bars doesn't leave much room for much else.. it's small and brighter than my bigger light on my other bike...actually it's blindingly bright if you look right at it. It's usb rechargeable. The charge seems to last a few hours.. so I usually recharge it every night. It just straps on with a velcro strap.



from http://www.singletracks.com/blog/mtb...-light-review/

"The front Flea has 4 white LEDs and has steady, overdrive (slightly brighter steady) and flash modes. This Flea is right on the edge between a see and be-seen type of light. The beam it casts is slightly broader than a spot beam, with soft edges and a good amount of peripheral light. For asphalt riding it is good to about 12 to 13 mph before you start to out ride the light (where you can’t see far enough ahead to safely avoid road hazards). Off-Road the illumination it provides is acceptable so long as the trail has good contrast to the surrounding landscape. This time of year (late fall) when there are leaves both on and off the trail I had to slow down considerably. As a supplemental light to a good bright helmet light the Flea’s performance is flawless. When used as a be-seen light the flash mode does an outstanding job of calling drivers’ attention to a cyclist or something else out of the ordinary coming at them - it borders on blinding at under 20 feet at night. Even in full daylight the flash mode is effective to make drivers pause and think “WHADAHECKISDAT!” Run time for the front light is advertised at 6 hours in flash mode– my run down test yielded about 6 hours, 15 minutes. The front light weighs an even 20 grams with the mounting strap."