BIKE FIT RESEARCH Aerodynamics isn’t everything: position also has an impact on metabolic cost. Jed Campbell-Williams describes his undergraduate research on the effect of bike set-up on cardiorespiratory function.
I
n bike fit, back angle or torso orientation is an
THE STUDY
important consideration, as it’s often the
This article is based on the results of an
difference between an aggressive and a
undergraduate sports science dissertation. There
relaxed position.
were two questions being asked by the
Lowering the back angle can help to decrease
researcher; the first was looking into whether
the frontal area of the rider, which in turn helps
decreasing torso orientation at a set power
to reduce aerodynamic drag. And as we all know,
output increased the load on the heart and lungs.
lower drag means more speed for the same
The second looked at how different power
effort.
outputs changed how torso orientation impacted
However, with most riders it simply isn’t
the body.
appropriate to fit the longest stem in the shop,
The study consisted of two separate visits for
slam it as low as it will go and expect them to
each participant. Visit one included a ramp test
ride faster. Other factors must be considered
to identify ventilatory thresholds. The threshold
such as the rider’s comfort, biomechanics and
analysis gives two key values — the ventilatory
physiology.
threshold (Tvent) and the respiratory
