91É«ÇéƬ

IT’S not just living things that evolve. Bicycles do too. In a study of
bicycles from the 19th century, Alberto Minetti and his colleagues at Manchester
Metropolitan University found that as new models were introduced, riders could
reach higher speeds for the same effort (Biological Sciences B, vol
268, p 1351). The team calculated the metabolic cost of pedalling the bikes by
monitoring the oxygen uptake of cyclists as they rode. Even early models such as
the 1817 Hobby Horse required less energy than walking or running because they
provided partial support for the rider’s weight, freeing up more leg power for
propulsion. Later innovations such as gears, pneumatic tyres and seats that
improved support for the rider reduced still further the metabolic costs of
pedalling.