you don't want to see a picture of my speedo trust me... i've done 39.7mph (i was so annoyed i didn't break 40mph) the fastest ever was that guy in japan that (i think) made it to 131mph before his front wheel came off.

edit - oh wait my speedometer? hehe, i've changed the battery since then so now it says 31mph which is pretty much the max i can get on knobbies around my house.