On the Design of a Recumbent Bicycle with a Perspective on Handling Qualities

A novel approach to bicycle design for handling qualities is presented. The design method is introduced through a case study in which a new front-wheel drive recumbent bicycle is developed. Since there exists no proper definition nor assessment for bicycle handling qualities, design process is based on comparing the uncontrolled dynamics of the new concepts to an existing design, known to handle well. A prototype was built and road test were conducted to compare the handling before being taken into production. The new design shows comparable handling. INTRODUCTION An important aspect in bicycle design is handling quality. Unfortunately, handling qualities of a bicycle are not well defined and mostly rely on subjective rider test trials [1]. Some more experience on handling is available for motorcycles, for a recent overview see Popov et al. [2]. However, for motorcycles the main issues concern handling at moderate to high speed, which is not the issue for bicycles. For bicycling low speed is of interest, that is in a forward speed range of 0 to 20 km/h. The common practice in the design process of bicycles is to use manufacturer experience and the trial and error method to come to new designs. This evolutionary process is lengthy and cumbersome, and usually leads to suboptimal designs. The aim here is to design bicycles for specific handling qualities. ∗Address all correspondence to this author. A proper definition of handling qualities involves the dynamics and control of the complete system: bicycle plus rider. A recent upheaval in bicycle research [3, 4, 5, 6] focuses mainly on the bicycle whereas still little is known about the rider. Some initial work has been done in the 70’s on bicycle rider model identification by Van Lunteren and Stassen [7], but these results are limited and inconclusive. A recent paper by Hess et al. [8] focusses on control models for the bicycle rider, for which unfortunately no experimental validation is available yet. One conjuncture is that handling qualities are closely related to the dynamics of the uncontrolled vehicle [6]. Moreover, recent experimental observations on bicycle rider motions [9, 10] show that the rider does not really move relative to the bicycle and thus that a rigidly attached rider could be a valid way to model the uncontrolled system. That is the approach we will use here. Starting from an existing design with good handling qualities, as perceived by experienced riders, the uncontrolled stability of the bicycle-rider combination is determined with a computer model. The new design will be made such that it matches the open loop stability of the existing one in the operational forward speed range. As a case study the design of a new front-wheel drive recumbent bicycle for the firm Raptobike [11] is presented. Note that on a recumbent bicycle the rider is not able to move relative to the rear frame, this makes the applied rigid rider model approach even more valid. The paper is organized as follows. After this introduction the design problem is stated. Next the methods are explained. 1 Copyright c © 2012 by ASME Proceedings of the ASME 2012 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference IDETC/CIE 2012 August 12-15, 2012, Chicago, IL, USA