2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
Figure 4. Estimated correlation between
the transmitted radiant flow to the scalp
(from Fig. 2) and the forward vent area
determined (Brühwiler et al., 2006) at a
tilt angle of 30°. Removing the extreme
point with the largest vent area reduces
the correlation and significance, as
shown.
nude head when wearing a bicycle helmet.
428
sizeable. At the same time, removing the point
with the extremely high value of vent area
reduces the correlation and, in particular,
reduces the level of significance to the border
of acceptability, underlining that different
criteria are important for the two types of heat
transfer.
DISCUSSION
The present work shows that bicycle helmets,
although generally a limitation on air flow and
forced convective heat loss, can reduce the
solar radiant flow by up to 75% in the present
experimental configuration, corresponding to
about 15 W on a sunny day. The visors tend to
increase these numbers, primarily by
protecting the face. Elsewhere, it will be shown
that visors can change the convection-induced
heat loss. Since the helmets often decrease the
convective cooling by less than 10 W under the
given climatic conditions (Brühwiler et al.,
2006), the present work establishes that the net
heat exchange from the head to the
environment can be greater than that of the
REFERENCES
Bogerd, C. P., Heus, R. & Willems, J. (2005) A sun shading headgear used by a Dutch
olympic sculler: A comparative study. International Conference on Environmental
Ergonomics. Ystad, Sweden.
Brühwiler, P. A., 2003. Heated, Perspiring Manikin Headform for the Measurement of
Headgear Ventilation Characteristics. Meas. Sci. Technol. 14, 217-227.
Brühwiler, P. A., et al., 2006. Heat Transfer Variations of Bicycle Helmets. J. Sports Sci. 24,
999-1011.
Brühwiler, P. A., et al., 2004. Bicycle helmet ventilation and comfort angle dependence. Eur.
J. Appl. Physiol. 92, 698-701.
Buyan, M., et al., 2006. Facial Warming and Tinted Helmet Visors. Int. J. Ind. Ergon. 36, 11-
16.
Cotter, J. D. & Taylor, N. A. S., 2005. The distribution of cutaneous sudomotor and
alliesthesial thermosensitivity in mildly heat-stressed humans: an open-loop approach. J.
Physiol. (London) 565, 335-345.
Ellis, A. J., 2003. Development of Fundamental Theory & Techniques for the Design and
Optimisation of Bicycle Helmet Ventilation. Ph.D. Thesis, Dept. of Aerospace
Engineering. Melbourne, RMIT University.
Ellis, A. J., Bertolini, A. F. & Thompson, L. A., 2000. A review of research on bicycle helmet
ventilation. Sports Eng. 3, 185-194.