While helmet wearing reduces the severit of injuries in motorcycle crashes, it may also increase the likelihood of getting involved into a traffic accident through a reduction in the rider’s field of view. We thus investigated the perceptual effects of helmet wearing when riding a motorcycle. The task consisted of negotiating curves in a fixed-based motorbike simulator while the helmet visor vertical dimension and need to check the handlebar-mounted speedometer were manipulated. Decreasing the vertical aperture below roughly 30 deg significantly impaired a rider’s ability to maintain their lane position and speed; with the effect of aperture being significantly greater when speedometer checking was required. The present findings help to quantify the tradeoff between physical and perceptual effects in helmet design.