Handlebar vibration of a motorcycle during operation on different road surfaces

In Japan daily motorcycle mail deliverers have been exposed to vibration from the handlebars of their motorcycles. Handlebar vibration was measured during the operation of a motorcycle in order to evaluate the hazardous effects of vibration and to identify preventive measures against the vibration hazards. Tests were made on asphalted, unpaved, and packed-snow road surfaces. The tested motorcycles were selected from the many motorcycles in daily use. The test motorcycle was a 1-cylindered, 89-cm3, 4-cycle machine. The direction showing the maximum value of vibration acceleration was not always in the directions of X, Y, and Z proposed by the International Organization for Standardization (ISO). The maximum vibration acceleration level exceeded the exposure guideline of ISO, while its frequency corresponded to that of the engine speed during operation. Vibration of greater than 20 Hz was transmitted through the front forks from the road surface and tires.