More watts thanks to BOA? What lies behind the performance and aerodynamic claims

Better performance thanks to a better fit?

BOA cites research suggesting that a precise shoe fit can improve power transfer and enable performance gains of up to 22 watts during sprinting. The basic premise is plausible: a cycling shoe that securely wraps around the foot reduces movement within the shoe and provides a more direct riding sensation.

However, one should not conclude from this that the fastening system alone is responsible for the improvement in performance. The fit of the shoe itself remains the decisive factor. If the last shape and the foot do not match, even the best twist fastening system cannot turn it into a perfectly fitting shoe. Above all, the BOA system allows for very precise adjustment of the tightness, thereby enabling the optimal use of a shoe that already fits well.

Another practical advantage: modern BOA systems can be fine-tuned in small increments whilst riding. Many of the latest fastenings allow you to both tighten and loosen them without having to open them completely. Professionals, who predominantly ride their sponsors’ top-of-the-range models, benefit from this in particular.

Aerodynamic advantage, subject to certain restrictions

When it comes to aerodynamics, BOA also highlights the advantages of a flat, integrated fastening system. In fact, exposed Velcro strips or laces potentially create more drag than a compact twist lock. However, the extent to which this actually affects performance on the road depends heavily on the specific design.

Not every BOA fastener is aerodynamically identical. Protruding rotating wheels or heavily knurled metal surfaces can, in turn, create turbulence. Furthermore, the fasteners are located in a part of the cycling shoe that, aerodynamically speaking, has relatively little impact anyway.

More importantly, in time trials, many professionals wear overshoes or aero booties. These cover the shoe and fastenings almost completely. The measurable aerodynamic advantage then arises primarily from the smooth surface of the overshoe rather than from the fastening mechanism underneath. The situation is different for triathletes, who often do without booties in the transition zone due to time constraints.

TOUR SUMMARY

The study supports a finding that has long been accepted in cycling: a well-fitting shoe can improve performance and comfort. However, the decisive factor remains the fit of the shoe as a whole, not just the fastening system. BOA offers a precise solution to this, one that is widely used in the professional peloton. The promised performance and aerodynamic benefits should, however, be regarded as part of an overall system rather than as a feature of the twist-lock mechanism alone.