Out of all the vids you've posted so far, i think this one has the best audio quality. There was one other (under the seat behind the regulator I think) that sounded pretty good, but the sound had a tendency to drop out when your motor hit certain rpm ranges (namely when you were at 5/6k and dropped off the throttle suddently. I agree, at least two if not three mics would be ideal. Nice set of videos though. A couple of local guys here have gopros and I think yours has a touch better quality.
Thanks for the feedback! I also prefer the audio in the most recent clip (mic under the tank). It has an entertaining quality to it.
I think the other one you liked was with the mic behind the cluster so that it picks up mainly the sinister induction noise from the open airbox with throttle roll-on. Steady throttle or closing throttle produces essentially no induction noise, so the sound drops off as you noticed. I didn't actually post any clips with the mic behind the regulator (just described it).
I promised myself that I'd keep the scope of the project to a single mic, but I've already started to piece together a second mic. It's a slippery slope thing. I really need to capture some of that deep induction growl and blend it with the motor and exhaust note from the last clip.
It looks like Vholder has a new true HD helmet cam out, and Axial Video also has a new high-end cam available. Gopro has unmatched bang for buck. Lots of good options out there.
BK