Ive done an an average speed of over 40 mph for 5miles flattish road

also done an average of 21mph for 53miles to Aberdeen. Not very flat. reved out in top going past Stonehaven.

But that was on my Bob Jackson road bike. With a 52 X 13 with 700c size sprints and tubs
that bike flew and I was a little bit fitter then

Have seen 38mph on my grifter on the beach
thats a similar bike to the shopper