So above is the first test shot, which you can tell is way too dark. So i had to think of a way to better illuminate the rider. So obviously a flash was called for, but i really wanted to avoid using an on camera flash, so i thought of the set up below.
The bike on the right w/ the camera is the one my friend Sean would be riding while I would ride the bike on the left about 10-15 feet in front of him and to the left with a Canon 580ex flash attached to my seat post. I really wanted a natural look to the image, which is why i decided to have the flash off camera. I also placed a full CTO gel over the flash to match the warm colored street lights. The flash was dialed down to about 1/16th power so it wouldn't over power the ambient light. The flash also allowed me to "freeze" the rider since the exposures were 1 second or more. Below are some of the final results.
(Both images were shot with a Canon 5d w/ a 16-35mm lens set at 16mm, the exposure was 1.3 seconds at f-2.8 at ISO 800. Both were lit with the Canon 580 flash on my seat post in front of Sean.)
The image above with the trees is my favorite from the shoot. The warm light from the street light and the feeling of just flying by under the trees worked perfectly for what i was going for. I do plan on trying another set up with this rig in a parking garage in downtown Albuquerque, so i'll update later with how that one works out.