Power development in hill climbing as a function of bicycle weight

Abstract

The purpose of this research was to evaluate the effects of differences in the weight of bicycles on power development while riding uphill. Thirteen competitive bicycle racers performed two hill climbs in a single exercise session up a 1.78 mile hill on which they have previously trained. During both hill climbs the subjects rode their own bicycles which were previously fitted with a Saris Cycling Group PowerTap SL 2.4 power meter on the rear wheel of the bicycle. During one climb 1.0 kg of sand was added to a water bottle on the bike frame to determine the difference in wattage per gram of weight added to the bike. The order in which the bikes were weighted was randomized to keep the riders from knowing if they had the bottle filled with 1.0 kg of sand or if they had the one that was empty. The subjects were allowed 30 minutes to recover following the first hill climb before starting the next one.

The maximum wattage output with 1.0 kg weight added to the bicycle was consistent among all of the test subjects except two, with an average increase of 53.77 watts being produced. Another factor that was constant among all of the subjects except one was an increase in the amount of time it took them to reach the summit of the climb with the 1.0 kg weight added to their bicycle. The average amount of extra time was 21 seconds. The average power output for the entire group of test subjects with the 1.0 kg weight added to their bicycle during the hill climb was -3.462 watts. The results showed that when weight is added onto a cyclist or their bicycle, the effort (power measured in watts) at which they need to maintain the same speed they are able to travel with a lighter bicycle is significantly increased.

This type of information is important to those who would like to know how they can ride their bicycle to the summit of a climb faster than before. Those who might have particular interest in these types of results would be the athletes who compete in bicycle racing. The numerous materials that are used in today’s manufacturing of bicycle frames and components allow cyclists to measure each gram of weight that they either put onto or take off of their bicycle. Knowing just how much time and energy they are saving or losing from those grams helps the athlete when it comes to both training and racing.