Article

Simulation of Bicycle-Riding Smoothness by Bicycle Motion Analysis Model

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

This study focuses on the development of equipment for measuring riding smoothness along bicycle routes. In addition, a bicycle motion analysis model was also developed and verified for conducting effective and efficient assessment of riding smoothness. Compared to motor vehicles, bicycles have a relatively simple shock absorber design. Most of the motorway smoothness indices developed for passenger cars do not satisfy the needs of evaluating bicycle routes. A test bicycle equipped with multiple sensors was developed in this study to measure the vertical acceleration while riding a bicycle. A lightweight inertial profiler was also designed and manufactured for measuring the bicycle route profile, which was used as the major input of the analysis model. Through several stages of field tests, it was concluded that the measured and calculated accelerations are fairly consistent, and the average error percentage is less than 10%. By integrating the usage of a lightweight inertial profiler and the bicycle motion analysis model, riding smoothness of bicycle route networks can be assessed effectively and efficiently.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The dynamic behaviour of two-wheeled vehicles is a well-known research topic. In most cases, the aim is to evaluate comfort and safety through the response of the vehicle to the roughness of the road surface, usually assessed by a measurement of the vibrations absorbed by the vehicle or user (Bíl et al., 2015;Chou et al., 2015;Gao et al., 2018;Feizi et al., 2020). On the one hand, the most studied two-wheeled vehicles were motorcycles, for which the relationship among vehicles' design characteristics, surface type, and riding performance is currently well known. ...
... ISO 2631-5 proposed an additional method for the evaluation of the effect on health of vibration containing multiple shocks, such as lumped obstacles like potholes, steps, and other significant irregularities in the road surface. When ISO 2631 was not followed, a new evaluation index for comfort is proposed processing acceleration data through customised mathematical procedures (Chou et al., 2015). In some cases, the acceleration data were processed through statistical techniques (e.g., linear regression and ANOVA analysis) and returned the effect between the acceleration and several predictors (Gao et al., 2019). ...
... Specifically, as for bikes, several studies showed that vibrations increase at increasing speed (e.g., Bíl et al., 2015;Gao et al., 2018). In addition, the macrostructure and properties of the road surface are crucial for vibrations on bikes (Chou et al., 2015). Particularly, uneven old stone pavements and damaged roads are the most uncomfortable surfaces (Bíl et al., 2015). ...
Article
E-kick scooters are currently among the most popular emerging electric-powered Personal micro–Mobility Vehicles (e-PMVs) and have recently been equated to e-bikes. However, even if the dynamic behaviour of e-bikes is well studied, much less has been done to understand the behaviour of e-kick scooters. Furthermore, comparisons between the two vehicles have rarely been investigated and only based on mechanical models. This study covers this gap by proposing a novel framework that evaluates the vibrational behaviours of both vehicles when driven by different users and exposed to the pavement irregularities, using both real and simulated data. The experimental data are collected equipping an e-kick scooter and an e-bike with Inertial Measurement Units, and then processed by ISO 2631–1 method to obtain an objective evaluation of the comfort. Next, the experimental data are expanded to include uncertainty applying a Monte Carlo Simulation based on a two-layer feed-forward Artificial Neural Network. Afterwards, several statistical analyses are performed to understand the key factors affecting the vibrational magnitude (and their extent) for each vehicle. This framework was tested in an Italian city (Brescia) along urban paths with five different pavement surfaces. The results showed that the e-kick scooter appears to be globally more solicited than the e-bike in terms of vibrational magnitude. Moreover, pavement surface, sensor position, user gender, user height, and travel speed are identified as crucial factors explaining the vibrational magnitude for both vehicles. The overall findings challenge the recent European regulations that equated e-kick scooters with bikes. These findings may help public administrations in planning the circulation of e-bikes and e-kick scooters in cities and recommend that manufacturers improve the e-kick scooter design by including shock absorbers to increase comfort.
... The dynamic behaviour of two-wheeled vehicles is a well-known research topic. In most cases, the aim is to evaluate comfort and safety through the response of the vehicle to the roughness of the road surface, usually assessed by a measurement of the vibrations absorbed by the vehicle or user (Bíl et al., 2015;Chou et al., 2015;Gao et al., 2018;Feizi et al., 2020). The most studied two-wheeled vehicles were motorcycles, for which the relationship among vehicles' design characteristics, surface type, and riding performance is currently well known. ...
... ISO 2631-5 proposed an additional method for the evaluation of the effect on health of vibration containing multiple shocks, such as lumped obstacles like potholes, steps and other significant irregularities in the road surface. When ISO 2631 was not followed, a new evaluation index for comfort is proposed processing acceleration data through customised mathematical procedures (Chou et al., 2015). ...
... Bíl et al., 2015;Gao et al., 2018). In addition, the macrostructure and properties of the road surface are crucial for vibrations on bikes (Chou et al., 2015). Particularly, uneven old historical stone pavements and damaged road portions are the most uncomfortable surfaces (Bíl et al., 2015). ...
... Moreover, some studies intended to use an instrumented bicycle for assessing the riding quality of cycling facilities based on vibration measurements. In order to register this variable, Bil et al. [11] used a system with a GPS and a data logger with accelerometers (MSR145s); Chou et al. [12] equipped a bicycle with an accelerometer, a distance measurement instrument, a speed meter, and a data acquisition system; and Ambroz et al. [13] used a system based on Raspberry Pi with two tri-axial accelerometers, a wire potentiometer, and a magnetic reed-switch based speed sensor. In addition to these sensors, vertical acceleration measurements for assessing the quality of bicycle infrastructures have also been collected using a smartphone [14,15]. ...
Article
Full-text available
In recent years, cities are experiencing changes in the ways of moving around, increasing the use of micromobility vehicles. Bicycles are the most widespread transport mode and, therefore, cyclists’ behaviour, safety, and comfort have been widely studied. However, the use of other personal mobility vehicles is increasing, especially e-scooters, and related studies are scarce. This paper proposes a low-cost open-source data acquisition system to be installed on an e-scooter. This system is based on Raspberry Pi and allows collecting speed, acceleration, and position of the e-scooter, the lateral clearance during meeting and overtaking manoeuvres, and the vibrations experienced by the micromobility users when riding on a bike lane. The system has been evaluated and tested on a bike lane segment to ensure the accuracy and reliability of the collected data. As a result, the use of the proposed system allows highway engineers and urban mobility planners to analyse the behaviour, safety, and comfort of the users of e-scooters. Additionally, the system can be easily adapted to another micromobility vehicle and used to assess pavement condition and micromobility users’ riding comfort on a cycling network when the budget is limited.
... This relationship affects the vibrations that increase at increasing speed (e.g., Gao et al., 2018). In addition, the macrostructure and properties of the road surface are crucial for vibrations on e-bikes (e.g., Chou et al., 2015). Gao et al. (2019) showed how the pneumatic pavement interface can be considered as a key connection between vibrations and the macro-texture of the pavement. ...
Article
Full-text available
Being the most popular among electrical-powered Personal micro Mobility Vehicles (e-PMVs), e-kick scooters have recently been equated with bikes (or e-bikes) by some European regulations. However, the similarity between e-kick scooters and bikes could be somehow questionable, due to their different characteristics. While the literature has studied the dynamic behaviour of bikes and e-kick scooters separately and has made some theoretical comparisons based on analytical models, no study has compared these two vehicles using experimental data. This paper covers this gap by evaluating the vibrational response (which can affect users’ comfort during a ride) of e-kick scooters and bikes at the pavement irregularities, using real data. First, kinematic data on accelerations were collected by two Inertial Measurements Units (IMUs) and then analysed adopting the basic vibration evaluation method proposed by ISO 2631-1. Then, several Z-test between the means of the vibrational magnitudes and two multiple regression analyses were performed: the first to investigate whether significative differences exist between the vibration magnitude acting e-kick scooter and e-bike, and the second to understand which factors affects this vibrational magnitude for each vehicle. A significant difference emerged between these vehicles as the mean of the vibration magnitudes measured on the e-kick scooter was higher than that measured on the e-bike. Hence, e-kick scooters appeared to be globally less comfortable than the e-bikes. Furthermore, the vibration magnitudes acting on the e-kick scooter appeared to be more influenced by the path, user, and speed factors than those acting on the e-bike. This analysis revealed insights that could challenge the recent European regulations that equated e-kick scooters with bikes. Moreover, the results could help public administrations in regulating the circulation of e-kick scooters along city paths.
... Accelerometers can be used to determine the characteristics of the vibrations on cycleways (Wigan and Carney, 1985;Torbic et al., 2003;Hastings et al., 2004;Levy and Smith, 2005;Champoux et al., 2007;Yamanaka and Namerikawa, 2007;Du et al., 2009;Giubilato and Petrone, 2012;Hölzel et al., 2012;Olieman et al., 2012;Vanwalleghem et al., 2012;Arpinar-Avsar et al., 2013;Duvall et al., 2013 case of pathways used by wheelchairs; Macdermid et al., 2014;Parkin and Sainte Cluque, 2014;Ayachi et al., 2015;Bíl et al., 2015;Chou et al., 2015;Li et al., 2015;Takahashi et al., 2015;Ambrož, 2017). These investigations have shown the importance of measuring vibrations to evaluate the quality of the cycleways and the close relationship with user comfort. ...
Article
Growing interest in zero emission transport modes, such as cycling, is currently generating motivation to construct new cycle paths. However, transportation planners and managers cannot always rely on practical methods for allocating the resources (often limited) needed for inventories and assessing cycling infrastructures. The aim of this study is to develop a method for classifying cycle paths in terms of roughness and general conditions of the pavement surface. Inventory data and information regarding the infrastructure conditions were collected on-site using video recordings taken by an action camera directly mounted on a bicycle. Georeferenced vertical acceleration data were collected using a smartphone. Acceleration data of three different pavement surfaces (asphalt, concrete and concrete bricks) were registered. The results showed the lowest acceleration values for concrete pavement and the highest values for interlocking concrete pavement. The proposed method can be a practical and efficient approach to evaluate cycling infrastructures in terms of pavement condition.
... These health problems include fatigue, headaches, sleep disturbances, irritability, forgetfulness and impotence [43], carpal tunnel syndrome and tendinitis, hand-arm vibration syndrome, back musculoskeletal disorders [44,45], hand and arm blood flow issues (numbness and white fingers), knee pain, and back pain [46]. Accelerometers can be used to measure vertical acceleration by cyclists [47][48][49][50][51][52][53][54][55][56][57][58][59]. Unpleasant vibrations can be influenced by the condition of the pavement surface, which is a factor included in several bicycle stress level indicators that have been proposed in the literature [4,9,12]. ...
Article
Full-text available
Urban and transport planners need to assess the stressful conditions experienced by cyclists, considering that highly stressful situations can discourage people from cycling as a transport mode. Therefore, this study has two objectives: (1) to present a method for monitoring stress and other environmental factors along cycling routes using smart sensors; and (2) to analyze the influence of noise, vibration, presence of cycle paths, and the period of the day on stress experienced by cyclists. Data were collected in the city of São Carlos, Brazil, using stress and noise sensors, accelerometers, and Global Positioning System (GPS). Primarily, heat maps generated from the data made it possible to identify critical points of stress along the routes. In addition, the results of a logistic regression model were analyzed to identify the influence of the studied variables on stress. Although high levels of noise increased the odds of experiencing stress by 4%, very uncomfortable vibrations increased the odds by 14%, and the presence of cycle paths reduced the odds by 8%, an analysis of p-values and odds ratio confidence intervals shows, with a 95% confidence level, that only the period of the day influenced stress, as confirmed by the data. In this case, the odds of having stress increased by 24% in the afternoon rush hour compared to the morning rush hour.
... Other researches ( Wu., 2015) made remarkable progresses on studying the influence of pavement surface on bicycle ride quality, which demonstrated that the international roughness indexes (IRI), mean profile depth (MPD) and riding vibration are highly related with the comfort level. Generally, the vibration signals can be captured by installing one or multiple accelerometers on different parts of the bicycle, such as the handlebar, saddle or fork ( Chou et al., 2015;Gomes and Savionek, 2014;Olieman et al., 2012). ...
Article
Attainment of cycling comfort on urban roads encourages people to use bicycles more frequently, which has social and environmental benefits such as to improve air quality, alleviate congestion and reduce carbon emissions. Vibration is perceived by cyclists as one of the most important indicators of cycling comfort, and it greatly influences people’s choice of bicycles. However, a comprehensive correlation between cyclists' perception of comfort and cycling vibration has not yet been established in the current knowledge. In this study, a total of 46 sections of 24 urban roads (approximately 11,500m in length of asphalt pavements) in the city of Xi’an, China, were selected for field test. An innovative Dynamic Cycling Comfort (DCC) measure system consisting of an accelerometer, GPS logger and smart phone, was installed on the hand bar of a shared bicycle typically used in Xi’an, to record the dynamic data of vibration, trail, speed and mileage. Reliability of the DCC was verified, and the effect of test conditions (speed, bicycle type) on vibration evaluated. The vibration data were processed in accordance with ISO 2631 to quantitatively characterize the vibration level on each tested section. Furthermore, a total of 17 volunteers participated in this test, and the cyclists’ perception of vibration in each section was obtained via a purpose-designed questionnaire. The volunteers’ perception of environmental factors such as scenery, weather, road geometry, congestion and traffic condition were summarized to evaluate the influencing factors for cycling comfort. The thresholds of acceptable rate, comfort level and vibration perceptible level were established, based on the correlation between cycling vibration awv and subjective perception described in the questionnaire. In addition, the cycling comfort on the asphalt pavements (3,521 m) within Qujiangchi Park was mapped, to demonstrate the practical use of this study. Results showed that the DCC is able to capture the cycling data timely and accurately. K-means clustering analysis showed that the cycling vibration increases with the increase of cycling speed. Meantime, a heavier shared bicycle with solid tires results in higher cycling vibration compared with a lighter one with inflatable tires. In addition, the comfort level is proportional to acceptable rate, and inversely proportional to vibration perceptible level. The cycling comfort mapping for Qujiangchi Park proved that there is great potential to use the vibration (comfort) data to monitor pavement surface quality and for cyclists to determine their desirable cycling route. Results of this study should be interested by cyclists, bicycle manufacturers, transport planners and road authorities.
Book
Full-text available
Functional Pavements is a collection of papers presented at the 6th Chinese-European Workshop (CEW) on Functional Pavement Design (Nanjing, China, October 18-21, 2020). The focus of the CEW series is on field tests, laboratory test methods and advanced analysis techniques, and cover analysis, material development and production, experimental characterization, design and construction of pavements. The main areas covered by the book include: - Asphalt binders for flexible pavements - Asphalt mixture evaluation and performance - Pavement construction and maintenance - Pavement Surface Properties and Vehicle Interaction - Cementitious materials for rigid pavements - Pavement geotechnics and environment Functional Pavements aims at contributing to the establishment of a new generation of pavement design methodologies in which rational mechanics principles, advanced constitutive models and advanced material characterization techniques shall constitute the backbone of the design process. The book will be much of interest to professionals, academics and practitioners in pavement engineering and related disciplines as it should assist them in providing improved road pavement infrastructure to their stakeholders.
Article
Attainment of cycling comfort on urban roads encourages travelers to use bicycles more often, which has social and environment benefits such as to reduce congestion, air pollution and carbon emissions. Cycling vibration is responsible for the cyclists’ perception of (dis)comfort. How asphalt pavement's surface characteristics relate to cycling comfort, however, remains undiscovered. In this study, the cycling vibration intensity on 46 sections of 24 urban roads was tested using a dynamic cycling comfort measure system while the cyclists’ perception of vibration was identified via questionnaires; the cycling comfort was then defined based on the cycling vibration. To record the accurate pavement-tyre interface under a stable environment, a total of 19 pavement sections were scanned using a 3D digital camera. These 3D models were then 3D printed, which are used to conduct the pressure film test using a self-developed pavement-tyre interface test system. Three ranges of pressure films were adopted to characterize the pavement-tyre interface via 9 parameters, namely contact area (A c ), unit bearing area (B u ), stress intensity (S i ), stress uniformity (S u ), kurtosis (S ku ), spacing (Sp a ), maximum peak spacing (Sp max ), radius ratio (R r ) and fractal dimension (F d ), in consideration of the area characteristics, pressure amplitude, peak spacing and shape of the interface. Finally, the significant interface parameters were identified, and the regression model between interface parameters and cycling comfort was established. Results show that the cycling vibration was described to be ‘very comfortable’ when the human exposure to vibration level (a wv ) was less than 1.78 m/s ² ; ‘comfortable’ when the a wv was between 1.78 m/s ² and 2.20 m/s ² ; and ‘uncomfortable’ when the a wv was greater than 2.20 m/s ² . The average stress on rear wheel-pavement interface is higher than that of the front wheel. B u-0.6 , Sp a-0.6 , and F d-0.6 are significant to cycling vibration. The 2LW pressure film is recommended for use to measure the bicycle pavement-tyre interface. The recommended interface characteristics are less than 7 mm ² of the unit bearing area, 6 mm of average spacing and 2.38 of fractal dimension. Finally, dense asphalt mixture performs better in providing cycling comfort than the gap-graded asphalt mixture. Results of this study contribute to current knowledge on bike lane comfort and pavement design, the findings should be interested in cyclists, transport planners, and road authorities.
Article
A legacy inertial profiler treats accelerometer sensor data as ultraclean zero-noise data. This is not true in reality. The inertial displacement of an inertial profiler is calculated by double integration of raw accelerometer sensor data. The integral operation amplifies the noise to form direct-current drifting and a random-walk effect in inertial displacement. Introducing a high-precision real-time kinematic (RTK) global navigation satellite system (GNSS) receiver is helpful in suppressing the direct-current drifting and random-walk effect in inertial displacement. The fusion of GNSS and accelerometer sensor data relies on a Kalman filtering-based algorithm. However, a low-cost inertial profiler normally does not have a high-precision GNSS receiver. Therefore, this paper proposes a new Kalman filtering-based framework in which the laser rangefinder sensor will replace the GNSS as an observer to control the direct-current drifting and random-walk effect. In the new framework, the accelerometer sensor is assumed to be contaminated by noise, the pavement is assumed to be perfectly smooth, and the road profile essentially becomes observation noise. The new framework also incorporates a legacy algorithm based on high-pass filtering (HPF) and a newly proposed Kalman filtering-based algorithm into a unified framework. The legacy HPF-based algorithm is an open-loop mode, and the Kalman filtering-based algorithm is a closed-loop mode. The HPF-based algorithms involve a specifically designed high-pass filter that can cancel the poles of the integral operator on the unit circle, making the new inertial profiler system unconditionally stable. In the new framework, all variables in state vectors are post-HPF, so the chances of variables reaching their upper bounds or saturating next-stage wavelength filters are low. By leveraging the laser measurement as an observer, the closed-loop Kalman filtering-based algorithmcan contribute 20 dB greater attenuation to the low-frequency random walk than the open-loop solutions. The new inertial profiler can switch from legacy to Kalman mode when the strong random walk appears in real-time. Combined with a high-precision optical triangulation sensor, the precision of the newly proposed inertial profiler can reach the subcentimeter or even submillimeter level under a large speed range.
Article
Full-text available
Recent emphasis on alternatives to automobile transportation has brought to light deficiencies in basic research performed in bicycle traffic science. Because of limited opportunities to fund such research, it is prudent to use past research to develop design guidelines and provide a basis for planning future research efforts. Mainly toward the latter end, a comprehensive review of published basic research in bicycle traffic science (with relevance to U.S. traffic) is presented, and suggestions are made for research priorities.
Article
This paper presents a fuzzy logic control scheme for designing the active suspension system in a half car model. The major part of this active suspension system includes fuzzy logic control and actuator. In order to reduce the oscillation of the vehicle, the fuzzy logic control was employed in front of the actuator. It is very obviously, we can obtain low oscillation and passengers can feel not only the comfortable ride quality but also the safety of the vehicle. A grey relational analysis is also proposed in this paper to find the relationship between road conditions, vehicle velocity, and oscillation.
Article
Research group at the Université de Sherbrooke VéIUS commits to help the bicycle industry by developing materials, technologies, and design procedures, which improves the comfort and durability of the bicycle. Results of tests with a cyclist signifies that both (single input multiple output) SIMO and (multiple input multiple output) MIMO analyses give similar results for natural frequencies and mode shapes. The technique of operating deflection shapes (ODS) is very useful for understanding and evaluating the real-life dynamic behavior of a machine component or an entire structure. The aim of European standards EN 14781 and EN 14766 is to ensure that bicycles will be safe as practically possible. The study shows that an appropriate curve and the hot-spot technique can be used to predict the fatigue such as life of bike frames and components fabricated with thin, circular, and aluminum tubes.
Article
An increasing number of jurisdictions across the United States are exploring level of service (LOS) for multiple travel modes, in part as a result of the release of the Highway Capacity Manual 2010 (HCM 2010), as well as an increased focus on complete streets policies. One of the most important questions being asked by these jurisdictions is whether new multimodal LOS methods are sensitive enough to inform transportation investments, mitigate impacts, and prioritize future projects. For this paper, transportation professionals (public, private, and academic) were surveyed about the inputs believed to have the greatest effect on pedestrian, bicycle, transit, and auto LOS or the inputs thought to have the greatest likelihood of being changed (e.g., to mitigate an impact or to improve existing conditions). Sensitivity testing was then performed at locations in four cities to measure how the HCM 2010 multimodal LOS scores responded as these inputs were incrementally increased or decreased. Although many inputs performed as expected, the testing also found model responses that were of a questionable direction or magnitude. The results of this study are informative for agencies that are considering adopting the HCM 2010 multimodal LOS for mitigation, resource allocation, and strategic decision making. The results also provide a starting point for additional research needed to enhance multimodal LOS methods.
Article
Bicycles are environmentally friendly and easy to operate. However, the bicycling environment in Japan is inadequate compared with many developed countries. Bicycle accidents have been increasing in recent years, and safety measures are needed to improve the bicycling environment. Although road surface conditions have improved, as reflected in the recent barrier-free policy for elderly and disabled pedestrians, an uneven surface between the road and the crosswalk can help to reduce accidents by reducing running speed. Because the most frequent type of bicycle accident is a collision with a car at an intersection, the accident-prevention potential of an uneven surface at an intersection crosswalk was examined. Students were asked to run along specific routes, and speed and vibration changes when they passed through intersections were measured. On the basis of the results, an analysis was made of what road environments would benefit from an uneven crossing surface. An uneven surface was found to reduce speeds at intersections with limited sight distance. However, other appropriate safety measures must be applied to reduce bicycle speed when an uneven crossing surface cannot be used because of the barrier-free policy.
Article
The International Roughness Index (IRI) has become a well-recognized standard for measurement of pavement roughness. The main objectives of the study were to evaluate the consequences of switching to IRI roughness measurements, and to develop a procedure for switching from measuring roughness with a response-type device, used for more than 10 years, to an IRI device. The study consisted of two parts. In the first part, the repeatability and consistency of roughness measurements obtained by three different IRI-measuring systems using a 10-section calibration circuit was evaluated. In the second part, transfer functions relating IRI with a subjectively measured ride condition rating for a large pavement network consisting of asphaltic concrete, rigid, and surface-treated pavements were developed. Based on the results of the calibration circuit, the three IRI-measuring systems were proved equally capable of providing repeatable and reliable roughness measurements for network-level monitoring purposes, and their individual results correlated very well. However, because of systematic differences between the results, the IRI-measuring systems cannot be used interchangeably and without proper calibration. Based on the results obtained for the network, different transfer functions were required and developed for the four pavement types (asphaltic concrete, composite, jointed portland cement concrete, and surface-treated). IRI roughness measurements provided better prediction of the ride condition rating than the response-type roughness measurements. These results support the switch to IRI roughness measurements.
Article
An interactive bicycle simulator with six degrees of freedom motion system could bring the rider a very realistic riding feeling. An important component of the simulator is the full bicycle dynamic model that simulated the two-wheeled bicycle dynamics. It consists of two slightly coupled submodels: The stability submodel and the vibration submodel. The stability submodel solves the stability of the bicycle under rider's active maneuvers and the vibration submodel evaluates the vibration response of the bicycle due to uneven road surface. The model was validated by several experiments and successfully applied to the interactive bicycle simulator.
Surface treatment macrotexture and bicycle ride quality
  • Li H Harvey
  • J Thigpen
  • C Wu
A study of index of urban bicycle lane ridability
  • Y J Lin
  • C P Chou
Comfort analysis and parameter design for scooter riding
  • Z W Sun
  • T J Chen
  • C S Chen
Smoothness specification for freeway and highway pavements
  • L Lin
  • C P Chou
Predicting bicyclist comfort in protected bike lanes
  • M.-A F Nicholas
A study on comfortable effect of a bicycle rider with different dampers
  • M H Yang
  • M C Shih