BBC_Earth_UK_-_January_2017

126 / / JANUARY 2017

By taking inspiration from the natural world, cycle
companies are tapping into an emerging science called
biomimicry, emulating structures and strategies that have
evolved over millions of years. ‘The beauty of biomimicry
is that, throughout history, nature has solved a lot of
complex problems,’ says Michael Hall, director of advanced
development at bicycle manufacturer Zipp. Indeed, in
studying the fins of a humpback whale, Hall and his team
have been able to create a radical new bike wheel that reduces
aerodynamic drag and side force, making it easier to pedal
along and maintain a straight line.
‘We were coming up with ideas of how to make bike wheels
handle better,’ says Hall. His problem was that when typical
bikes are buffeted by gusts of wind from the side, the air does
not flow smoothly around the rim of the wheel. It becomes
turbulent, which destabilises the bicycle and makes it harder
to handle. So how did he solve the issue? By looking at the
agile way a humpback whale swims.
‘Humpback whales are as big as a bus and they swim these
tight manoeuvres to create a bubble mass and trap their prey,’
Hall says. ‘They can do that because they essentially have
these vortex generators on their fins, which allow the water
to stay attached.’ Put simply, a humpback whale fin has
bumps along the front edge called tubercles, which modify
the flow of water around it, giving the flipper a slight lift and
a lower drag. It allows a 16m-long mammal that weighs 36
tonnes to swim up to 27km/h and turn a radius of 1.5m.
Taking this as their inspiration, Hall and his engineers
developed an undulating wheel rim, spending 252 hours
playing around with 36 prototypes in order to biomimic
what they saw in the humpback whale. They found that the
randomness of the bumps appeared to be important, too,
minimising the collection of air.
‘Biomimicry is an effective solution to the problem of
making cyclists faster and more efficient,’ says Dr Xavier
Disley, director of cyclist performance analysts AeroCoach.
He explains that the knee and the hip extension are the
foundation of human movement, and bike design cleverly

A large vortex of swirling air creates heavy drag

A smaller vortex creates less drag

Smooth ball:

Air flows smoothly around the ball and

quickly detaches, so increasing drag

Dimpled ball:

Dimples on the surface manipulate

the airflow so it stays attached and

creates less drag

Swing into action

A golf ball makes use of the

same principle of bumps on its

surface to reduce drag. Originally

smooth, manufacturers began

making dimpled balls in the late

19th century after golfers noticed

that balls with nicks and dents

in them travelled farther. Like the

whale fin, the bumps create a

turbulent layer of air that clings

to the ball, decreasing the size of

its wake, and therefore the drag.

Humpback wheel:

despite being as big as

a bus, humpbacks can

make a really tight turn

in the water, thanks to

their pectoral flippers