The number of adult bicycle helmet users in Sweden has stayed over the years relatively stable around 20 % [1]. In Europe the number of helmet users varies between 1 and 40 % depending on country. Research has shown that the use of helmet considerably diminishes head injuries in the case of traffic accidents [2]. In spite of that it is not fully clear what are the main factors why only a small number of bicyclists use a helmet. In order to raise awareness of helmet use and improve traffic safety COST Action supported a European initiative “Towards safer bicycling through optimization of bicycle helmets and usage”. Why helmet use is not popular? Several reasons could be pointed out: design, destroys the hair style, attitudes against helmet use, nowhere to put, too warm etc. Often the initial complaints are related to heat [3]. In cold additional insulation from the helmet may be a positive factor while compatibility issues may rise. As the professional bicyclists and most training/competing amateurs do wear the helmets then the aim for traffic safety should be increasing helmet use among commuters and bicyclists who do it just for fun. Therefore a project was initiated where main issue was to reduce initial thermal disturbance from a bicycle helmet while keeping in mind visibility, protection aspects, look, issues related to wearing comfort etc. Some relevant factors to be considered are: • The motion speeds of commuters would stay on average around 15 km/h (4.2 m/s) with average high speed not much above 20 km/h. • Aerodynamics and placement of the vents and air channels. • The effect of hair should not be underestimated – these may fill air channels with very effective insulation material
