The Cree U2 LED has a 5000K color temperature minimum, I think that's where the "5000" comes from. It puts out 742 lumens @ 2 amps. The maximum input current is 3 amps. A pair of these might be good for 2000 lumens total, at 6 amps and about 3.3V, call it 20W.

Anyhow, I bought one of these $26 2x U2 jobs and it works great, amazing at the price. The mount does not fit (but probably works fine on) 31.8mm bars in the thick section, but fits well near the grip if you have a spot that is pointed the right direction.