Haha, 55.
I know that's the most effective way to improve the ol' mpg, especially on a motorcycle, but speed limits here are 70mph, and highway cruising speed is 80 and up.
I'll take 300 miles a tank if I can get it without sacrificing too much torque to zip around #$*%heads on the highway and get in front of Corvettes pulling away from stoplights. I mean, when I'm just riding around town I usually shift before the torque peak, so I could go up a few notches and just shift later without sacrificing much.