I've been up towards 50mph but not quite there, about 46/47 mph. You have to know your brakes are gonna work!!!
And I'm not too macho to admit that I was crapping myself, especially when you start thinking that your only contact with the ground is two thumbnail size pieces of rubber!!
It is fecking great though!! 
Oh but going over a cattle grid at that speed is no fun 
Edited: 27/06/2011 at 17:48