4. CONCLUSION

Through extensive wind tunnel measurements, we determined that the aerodynamic drag of TT cyclists can be significantly reduced through the development of streamlined TT apparel. The most effective apparel design innovations proved to be:

1. The use of lightweight stretch fabrics to allow adequate thermoregulation during extended periods of exercise.
2. The development of a garment pattern that produces the fewest wrinkles when the suit is worn in the TT position.
3. Custom fitting of each suit to the cyclist to minimize wrinkles or areas of loose fabric.
4. In regions of attached flow, the use of flat seams aligned parallel to the flow direction.
5. Placement of the majority of seams towards the rear or in regions of separated flow, where they have no impact on drag (Figure 7).
6. Placement of necessary cooling panels in shielded regions out of the air stream.
7. In zones of attached airflow, such as the torso, smoother fabric textures were utilized to minimize skin friction.
8. Appropriate fabric textures were carefully placed in cross-flow zones to induce boundary layer transition from laminar to turbulent, and thereby reduce the low-pressure wake behind the segment.
9. The upper arms, thighs, and calves encounter cross-flow where appropriate surface textures of fabric were found to provide less air drag than bare skin. Although longer sleeves and tights might provide enhanced aerodynamic benefits, garment length appears to be determined by customs, regulations, cooling requirements, and factors other than aerodynamics.

3.2.2.4 Clothing
The design, fit and aerodynamic attributes of athlete clothing can all contribute to an improved athlete
performance, with a reduction in drag of 10% seen for athletes wearing appropriate clothing [Oggiano et al.,
2009, Kyle, 2003a]. The design of an aerodynamic skinsuit should have seams parallel to the flow or in
separated flow zones where they will not increase the drag, be close fitting to minimise wrinkles, be made of
smooth, rubberised material, cover body hair, and have any graphics out of the airflow [Oggiano et al., 2009,
Kyle and Weaver, 2004, Brownlie et al., 1991]. A cyclist is a bluff body for which pressure drag dominates.
Separation at low speeds can be delayed by inducing turbulence in order to minimise the aerodynamic drag.
This can be achieved by introducing trip wires, surface roughness, or dimples slightly upstream of the point
of separation. As the torso of a cyclist is nearly horizontal, smooth fabric should be applied in this area
where the flow is parallel as skin friction dominates [Brownlie et al., 2009].