Abstract

INTRODUCTION

The observation of the PTW accidents in France shows that they represent 23% of the fatalities whereas 2% of the traffic are motorcycles. Pre-crash calculations carried out in case by case studies on PTW accidents rely on braking data extracted from outdated publications. This paper aims to update PTW braking data in various conditions.

MATERIAL and METHODS

To do so, a series of about 400 experimental tests have been conducted on tracks using three motorcycles: Yamaha XJ6 (2010), Tracer 900 (2016), and FJR 1300 (2007). Tests were carried out by police instructor pilots at different speeds (30, 50 and 80 km/h), and with several braking setups: front and rear braking, only front or rear braking, with or without ABS, over-inflated and under-inflated tyres. Three tests have been performed for each configuration. Acquired data concern speed, accelerations, angular speeds … but the main relevant parameter considered was the longitudinal deceleration.

RESULTS

It results from those tests that 8.2 m.s-2 is the average deceleration with the front braking only, 3.5 m.s-2 with the rear braking only, and 9 m.s-2 with both braking. The ABS parameter emphasizes its use even the decelerations are a little stronger without it than with, except in case of a wheel lock-up where the deceleration drops of half its value. About the tyre pressure, it was noted that an under-inflated tyre tends to increase decelerations, whereas an over-inflated tyre has the opposite effect.

CONCLUSION

About 400 brake experimental tests have been performed in order to characterize the longitudinal deceleration of 3 PTW in different configurations. These data can be used in particular for accident reconstructions to evaluate PTW speed when ABS is actual or not, with over-inflated or under-inflated tyres, with brake applied only on front wheel, rear wheel or both.