What's your top speed?

Nudged 37.8 mph in the first floor of a pub courtesy of Rollapaluza. SS - not sure, probably only about 25-27 mph on the flat. Geared, top speed currently 52 mph (courtesy of the Cambrian Mountains).

On a regular run in Kent there are some great sections, just a little downhill gradient, where one can barrel along (geared) quite happily around 40 mph+ mark.

Coming from the top of Westerham Hill, through Biggin Hill towards Downe along the main road is my favorite. You can really get 53/12 spinning and keep it on for 2 miles or so. Especially with a chain gang.