The Influence of Static Factors on Seating Comfort of Motorcycles: An Initial Investigation.

OBJECTIVE: The aim of the current study is to examine the influence of static factors on overall seating comfort in motorcycles and validate the use of static lab-based setups for evaluating seating comfort in motorcycles. BACKGROUND: Seating comfort in automobiles has two factors, static and dynamic. Research on seating comfort of passenger cars has shown that when the magnitude of vibration reaching the seat is low, comfort is largely determined by static factors. Studies have also validated the use of static lab-based setups for research on seating comfort in passenger cars. Static lab-based setups are easy to develop, provide a controlled environment, and efficient for experimental research. The riding posture, mass distribution, and dynamics of a motorcycle differ from a passenger car and warrant further investigation to extend the results from the research on passenger cars. METHOD: The study compares subjective rating of seating comfort and objective measurement of seat interface pressure in two test conditions: a static lab-based setup and actual driving on a flat test track where the magnitude of vibration reaching the seat is low. The vibration at the seat is measured for the driving trial. A group of 18 male volunteers from TVS Motor Company participated in the study, and two motorcycles from the economy/executive segment of India are used in the study. The subjective ratings are analyzed statistically using analysis of variance (ANOVA) and Pearson's correlation. The vibration data are analyzed as per ISO 2631-1 to calculate the frequency-weighted acceleration, aw. RESULTS: The results show that there is no significant difference between the two test conditions either in the objective measurements or in the subjective rating of comfort. There is also a statistically significant correlation between the subjective ratings of seating comfort in static lab-based setup and actual riding (r = .77, p < .01, n = 36). The mean aw at the seat while driving in the test track used in this study is 0.2 m/s2. CONCLUSION: Static factors have a significant influence on seating comfort in motorcycles. When the vibration reaching the seat is low (aw ≤ 0.2 m/s2), seating comfort is largely determined by the static factors. The use of static lab-based setups for evaluating static factors of seating comfort in motorcycles is validated. APPLICATION: The results of this study enable further research to understand the human criterion for seating comfort in motorcycles using static lab-based setups which are easier to develop and provide controlled environment that is essential for any research.

Development of a Seating Comfort Questionnaire for Motorcycles.

Objective The aim of this study is to develop a reliable and valid Motorcycle Seating Comfort Questionnaire (MSCQ). Background Motorcycle seat development is an iterative process based on subjective evaluations; however, there are no established subjective tools for evaluation of seating comfort. Research also suggests that seating comfort in motorcycles is poor and needs improvement. The development of a MSCQ therefore is an important step that can enable further research and aid in improving the design of motorcycle seats. Method The MSCQ is developed following guidelines available in literature and referring to established questionnaires for seating comfort in passenger cars. The MSCQ is further refined based on pilot studies and interviews with experts. The final version of the MSCQ is then statistically evaluated for reliability and validity. The reliability is evaluated using a test-retest protocol with 31 volunteers. The validity is evaluated by comparing the ratings of the MSCQ with that of the Category Partitioning Scale (CP50 scale). The validity test is carried out with 15 volunteers evaluating five motorcycles using both scales. Results The results show that the MSCQ is reliable with a significant test-retest reliability coefficient ( r = 0.72, p < .01, n = 31) and internal consistency (Cronbach's α = 0.81, n = 31). The results also show that ratings of the MSCQ have a significant correlation ( r = -0.765, p < .05, n = 15) with that of CP50, establishing its validity. Conclusions A Motorcycle Seating Comfort Questionnaire is developed in this study with statistically established reliability and validity. Applications The MSCQ can be used as a tool for evaluation of seating comfort in motorcycles. The MSCQ can also form a basis for further research on motorcycle seating to develop prediction models and guidelines for the design of motorcycle seats.