EMETRION meters with - Görlitz AG

Bicycle racing has become
very popular in the last
few years. A reason for this
success is the feeling that it’s
‘live’ that the spectators get
during the races. Cycling is
open to everybody to practice
during their free time - maybe
not as fast as the aces do, but
just as enthusiastically. In
contrast with fencing or high
jump - which could cause injury
to part-time sportsmen -
everyone can hop on a racing
bike and start training.
But a lot of dedicated training
is essential to climb the “Alpe
d´Huez”, “Mount Ventoux” or
the “Col de Telegraph” at the
same speed as Armstrong and
Ullrich. Modern communication
technology is mandatory to train
effectively. Cycling is a perseverance
sport and a special interest
is focused on biometrics.
Optimised fat-burning rates, lactate
concentration resistance,
and training within predefined
intensity areas are the basis of a
modern training programme. But
how is the sportsman really doing?
To monitor his medical condition,
frequent diagnostics are carried
out in centralised laboratories
because the equipment necessary
is large and heavy and has not
been available for mobile usage
up till now.
The main training takes place
outdoors on the road. Amateur
and national cyclists ride from
15,-30,000 training kilometres,
candidates for a pole position in
the Tour de France are on the
saddle for about 60,000 kms and
more per year.
Whilst the fitness of the competitors
was judged by gut feeling
in former times (“he seems to be
sweating a bit more today compared
with last week ...”), a lot of
mobile equipment is now available
to assess physical fitness remotely
for the coaches, the team, and the
medical staff.
Biometrics is the keyword. It
means the continuous measurement
and recording of the
body during training, mainly the
heart rate, the speed, physical
power, the pedal strokes, and the
relative height climbed by the
sportsman.
The measurement of some of
these parameters is not as easy
as it seems. We are all familiar
with pulse watches with integrated
barometers that we can buy from
any department store. And the
measurement of speed – we all
know how to do this too with our
old bike speedometers.
The strokes are mainly measured
by magnetic sensors on the pedals
but the main problem is how to
measure the actual power generated
by the cyclist.
Of course, it is possible to calculate
the average power value from
knowing the weight of both rider
and bike, the rolling resistance
and the height climbed. But this
average does not take into account
headwinds and upward or
downward gradients.
The bandwidth of the absolute
power values is enormous. A
leisurely cyclist, riding in a flat
area weighing about 80 Kg (incl.
the bike), needs about 80 watts
of power for a trekking speed of
16 Km/h. To ride at a speed of 25
Km/h on a racing bike, the power
needed doubles (160 Watts).
To compare with professionals:
to win a time trial in the Tour,
the winner needs to generate
a constant 440-480 Watts for
more than an hour. And the top
sprinters, such as Erik Zabel, are
able to power their bikes at more
than 1,400 Watts – but this is
only for a maximum duration of
20 seconds.
But how can power be measured
on a bike? On stationary ergometers,
sensors are mounted on the
rotors and measure the braking
energy.
But such ergometers weigh 50
(Foto und Titelfoto Seite 1: Hoffmann)
11/2004 METERING automation 5