The 100 lumen seatpost-mounted rear light shines to the sides as well as toward the rear—similar to Light & Motion's easily stealable (and portable) lights we love—and is plenty bright. Both front and back are charged via USB charger, which is included. In hand, Sparse feels like a luxury system, with a definite heft to them.
Unfortunately, this might not be good news to weight weenies, but if you're worried about that, maybe get those gorgeous Zipp 404 wheels like the bike above. Safety and speed, but safety first. Remember, you can only win if you're alive.
Ethan Wolff-Mann is an editor at Supercompressor. He has owned many bike lights during the past few years. Other people now own them. Follow him on Twitter @ewolffmann.