SIR - May I take gentle exception to your description of the bicycle as a “humble machine” (“Bumpy roads”, August 2nd). The bicycle is the most efficient form of transportation yet devised by man, probably 100 times more efficient than walking; a cyclist can travel up to 1,600 miles on the equivalence of a gallon of petrol (according to the “Penguin Book of the Bicycle”). Brilliantly simple-yes, humble-no.

Alan Freeman
Cambridge, Cambridgeshire