The fastest I've gone is 44.3 mph, but I can't coast to it, I have to work my arse off and spin to get there. There's a long 3% or so hill that I do on my training rides, but I think it's the strong tailwind that pushes me more than the slight downhill pulling me to that speed. I love it.

I should add though that this stretch of road is straight. For me it's not the speed, it's the turns. IMO, taking speed into turns is where the real skill is and what separates the men from the boys. Otherwise, it's just the soap box derby.