Many pedal cyclists know that the wet weather braking performance of rim brakes employing rubber brake blocks and chromed steel rims is inadequate. Road tests were conducted to find combinations of brake block material and rim types which provided adequate braking in the wet and dry. Nine brake block sets were tested; these included rubber, synthetic and leather blocks. The rims tested were plain, dimpled and grooved chromed steel and plain light alloy. The bicycle used for comparative tests was equipped with a water reservoir and jets to each rim so the water application rate could be controlled. The loads applied on the brake levers were controlled by adjustable stops on the handlebars. Results are given for rubber, synthetic and leather blocks on chromed steel and on light alloy rims in both wet and dry conditions. It is noted that dimpled and grooved rims do not significantly improve wet braking performance over that for plain steel rims. Leather blocks were shown to be suitable in all the test conditions, while synthetic blocks were suitable only for light alloy rims. Some rubber blocks appeared to be suitable only for light alloy rims, but others were not. All the rubber blocks tested gave very long stopping distances in the wet on chromed steel rims. (Author/publisher)
Samenvatting