Originally Posted by
krome
Here is a chart:
http://www.powerstream.com/Wire_Size.htm
There is also a voltage drop calculator on the page.
I'd be more worried about durability. Will there be any flexing? Any wiring from the fork to the frame?
Yup - mechanical durability should be a bigger concern than current carrying capacity. Bicycles produce a lot of vibration and and the wires will slso be exposed to condensation, heat from exposure to the sun etc. Use larger wires.