*Article* **Analysis of the Effect of Mass Parameters on Motorcycle Vibration and Stability**

**Andrzej D ˛ebowski**

Faculty of Mechanical Engineering, Military University of Technology (WAT), 00-908 Warsaw, Poland; andrzej.debowski@wat.edu.pl

**Abstract:** This paper presents a vibration analysis method and an example of its application to evaluate the influence of mass parameters on torsional vibration frequencies in the steering system of a motorcycle. The purpose of this paper is to analyze to what extent vibration frequencies can change during their daily operation. These changes are largely due to the ratio of vehicle weight to driver and load. The complex dynamics make it very difficult to conduct research using simple models. It is difficult to observe the influence of individual parameters because they are strongly interrelated. This paper provides a description of the vibration analysis method, and the results are presented in the form of Bode diagrams and tables. On this basis, it was found that the driver, deciding on the way of using the vehicle and introducing modifications in it, influences the resonant frequencies of the steering system. Typical exploitation factors, on the other hand, do not cause significant changes, although they may contribute to increasing the sensitivity of the system to vibrations. The conducted analysis also showed some nonlinear changes in the dynamics of the system with linear changes of the parameter values.

**Keywords:** motorcycle dynamics; steering system; vibrations; wobble; shimmy; Bode plot; LabVIEW
