The metabolic cost of operating a bicycle generator light

The purpose of the study was to determine the metabolic cost of operating a bicycle generator (dynamo) light. Nineteen subjects (12 males, 7 females) volunteered to participate in the study. All tests were conducted using a multigeared road bicycle mounted on a Velodyne computer-controlled, electromagnetically-braked bicycle training simulator. A tyre sidewall-driven 6V 3W bicycle generator was attached to the bicycle frame. Tyre pressure was maintained at 6.12 atm. Gears were prescribed to produce simulated riding speeds of approximately 13 and 21 km h(-1) at 62 rpm. Subjects rode four, 5-min stages during the test session to evaluate riding under conditions of generator OFF or ON at each speed. Oxygen consumption, heart rate, and rating of perceived exertion (RPE) were recorded at the end of each minute. Paired samples t tests revealed significant differences between generator OFF and ON conditions for both the metabolic cost of cycling and heart rate at each of the speeds tested. There were no significant differences found between conditions for RPE. Bicycling with the generator ON increased oxygen consumption by 8.4% at 13 km h(-1) and 9.6% at 21 km h(-1).