An Analysis of Sport Bike Motorcycle Dynamics during Front Wheel Over-Braking

There is extensive literature on motorcycle skid/brake to stop testing on a host of motorcycle types, rider experience, brake system configurations and the associated deceleration rates. Very little information exists on deceleration rates involved with over-braking the front wheel. The subject of this paper addresses the deceleration rates of sport bike type motorcycles during over-braking of the front wheel. Based on the physics of a two-wheeled vehicle like the motorcycle, once the front wheel is over-braked and becomes locked, the rider has very little time to recover from the skid and often times falls. Another over-braking scenario, especially on sport bike type motorcycles, is the possibility of the rear wheel lifting and pitching over the front wheel. During the initial phase of braking, weight transfer to the front wheel occurs creating a greater level of traction. As the motorcycle begins to fall or pitch over, the weight on the front wheel decreases significantly and therefore the frictional force decreases significantly as well. The goal of this publication was to perform maximum front wheel brake testing that involves front wheel skid-to-fall as well as front wheel brake-to-pitch over scenarios on various sport bike motorcycles and determine an applicable deceleration rate.

Three motorcycles; a 2002 Kawasaki ZRX1200R, a 2006 Yamaha YZF-R6, and a 2013 Ninja EX300 were subject to various maximum front wheel brake tests. The speed of the motorcycle at brake application ranged from 50 to 60 mph. The results of the testing concluded that the average deceleration rates during front wheel skid-to-fall tests were in the range of 0.32-0.8g depending on the lean angle of the motorcycle at brake application. The average deceleration rates for the front wheel brake-to-pitch over tests were in the range of 0.8-0.86g.