Non-traumatic injuries specific to bicyclists may be linked to forces present at the interfaces between the cycle and rider. These injuries include weakness and numbness of the hands and wrists, soreness of the pelvis, skin problems in the groin, erectile dysfunction and impotence.

The first goal of this investigation was to measure the forces present at the rider/cycle interfaces. Vertical and shear loads were measured for ten (10) subjects in a common fit position. The crank arm angles at which the maximum and minimum forces occurred were also obtained using a motion analysis system, and regions of rider contact with the seat were visualized with a pressure mapping system.

The second goal was to determine the effects of different hand positions on measured interface forces. Vertical and shear loads were measured after moving the handlebars 5cm closer to, then 5 cm further from the subject. A statistical analysis was performed using the SAS Mixed procedure with a significance level a = 0.05. Several forces were significantly affected by changing the cycle’s handlebar position.

Vertical loads were greater than shear loads, and in combination they may be contributing factors in non-traumatic injuries at the groin and hands reported by bicyclists.