985 the Effect of Mountain Bike Suspension Fork Stiffness on Impact Acceleration Characteristics

Orendurff, Michael S.; Fujimoto, K.; Smith, Gerald A.

doi:10.1249/00005768-199405001-00987

Cited by 3 publications

(4 citation statements)

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“…An experimental study shows that larger tyre sizes and lower tyre inflation pressure, reduces the impact of track unevenness [2]. Another study shows that an optimum stiffness of front suspension fork can suggestively reduce vibration transmission to the rider [3]. Bicycle fitting is of great significance since an adjustment such that the knees at the bottom of pedal stroke are slightly bent and arms are not overextended is expected to be a relaxed position for riding [4].…”

Section: Introductionmentioning

confidence: 99%

Vertical stiffness of bicycle frame and its influence on rider comfort

Shah¹,

Shah²,

Mehta³

et al. 2020

SN Appl. Sci.

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This study reports on relation between bicycle frame and rider comfort. It involves developing a theory on interdependence of vertical compliance or stiffness of bicycle frame and induced human comfort. The factors affecting vertical stiffness/compliance are identified and varied to observe their influence. A standard diamond type bicycle frame is modelled and analysed which is generally used for on-road bikes, applying different materials to the frame to note its deflection on application of load, considering the structural and material properties. The results of the analysis confirm with stiffness trend associated with Young's modulus of the material. i.e., for the same structure and loading conditions, material with lesser Young's modulus offer more compliance. Reducing thickness of tubing is also observed to be increasing compliance of the frame, which can be achieved either by reducing the outer diameter or increasing the inner diameter, the former being more beneficial according to manufacturing standpoint. This is verified by generating a series of supplementary equations. An experimental analysis is performed to discern the most influential tube out of every other tubings forming the frame structure, wherein their thicknesses are decreased by 10% one at a time, keeping the rest as it is. The study accomplishes that as compared to rest of the tubes, more rider comfort can be achieved by making least changes to the seat tube cross-sectional thickness, to decrease vertical stiffness and therefore, comfort. The obtained conclusions can serve as a base for further studies involving cyclist comfort and bicycle frame design.

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Section: Introductionmentioning

confidence: 99%

Vertical stiffness of bicycle frame and its influence on rider comfort

Shah¹,

Shah²,

Mehta³

et al. 2020

SN Appl. Sci.

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“…Alguns estudos têm investigado os impactos durante a rebatida no tênis, no cabo da raquete (Hatze, 1992) e no punho e no cotovelo dos atletas (Hennig, Rosenbaum, & Milani, 1992). Outros identificaram as vibrações transmitidas a ciclistas com diferentes tipos de suspensão de bicicletas (Levy & Smith, 2005;Orendurff, 1997), e aquelas transmitidas ao corpo de corredores (Boyer & Nig, 2004;Jarrah, Qas-sem, Othman, & Gdeisat, 1997;Gottschall & Kram, 2005).…”

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Valores de impacto no corpo do judoca ao ser projetado pela técnica Ippon-Seoi-Nage

Piucco¹,

Santos²

2010

Motricidade

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Valores de impacto no corpo do judoca ao ser projetado pela técnica Ippon-Seoi-Nage T. Piucco, S.G. SantosEste estudo exploratório objetivou analisar as magnitudes e o tempo de duração dos impactos gerados em diferentes regiões corpo do judoca projetado pela técnica Ippon-SeoiNage. Participaram dois judocas faixas pretas, sendo tori (judoca que projeta) com 75 kg e 19 anos de prática, e o uke (judoca que cai) com 72 kg e 15 anos de prática. Foi utilizado um acelerômetro triaxial 4321 da Brüel & Kjaer fixado no punho, quadril e tornozelo do uke. Os dados foram coletados em ambiente laboratorial, sendo realizadas 10 quedas para cada articulação investigada, totalizando 30 quedas. Os maiores valores de impacto ocorreram no punho no eixo vertical (351.95 g) e os menores valores no quadril no eixo antero-posterior (5.18 g); os tempos de duração dos impactos foram maiores no quadril no eixo vertical ( .58 s) não havendo diferença entre o punho e o tornozelo. Considerando os altos valores de impacto encontrados, bem como o elevado número de repetição de quedas por treino no judô, sugere-se que sejam revistas as metodologias de práticas e o tipo de tatame utilizado, objetivando minimizar os possíveis efeitos deletérios dos impactos ao organismo dos judocas em longo prazo. Palavras-chave: judô, impacto, ukemi Magnitude and duration of the impact generated on the athletes' body during training in Ippon-Seoi-Nage judo techniqueThis exploratory study aimed to analyse the magnitude and duration of the impact generated on the athletes' body during training in Ippon-Seoi-Nage judo technique. Two black belt judo athletes were studied, the tori (the thrower) weighting 75 kg and having 19 years of practice, and the uke (the thrown) weighting 72 kg and having 15 years of practice. A Bruel & Kjaer 4321 Accelerometer Triaxial, fastened to the fist, hip and ankle of the uke, was used. Data were collected in the laboratory. Ten falls were performed for each of the three articulations investigated. The largest impact values were observed for the fist in the vertical axis (351.95 g) and the smallest values were for the hip anterior posterior axis (5.18g). Impact duration times were greater in the hip vertical axis (.58 s) with no differences for the impact on fist and ankle. Considering these high impact values as well as the high frequency of falls during judo training, it is suggested a reevaluation of this training pattern and the sort of tatami adopted, in order to decrease the resulting harmful effects over the time.

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“…Those bikes with suspension forks reduced vibration amplitudes by 30-60% at the frame compared to the axle for this range of frequencies. Similar studies to quantify the performance of suspension fork models observe significantly lower vibrations transmitted from the axle to handlebars when the stiffness of fork is reduced (Orendurff, Fujimoto & Smith 1994, Laser & Bauer 1997. There remains no doubt suspension plays an important and significant role on mountain bikes.…”

Section: Why Use Suspension For Mountain Biking?mentioning

confidence: 86%

“…It is widely supported that using suspension over rough terrain permits higher speeds for several reasons. Firstly, rougher terrain need not be avoided when suspension is used so straight-line velocity can be maintained and the centre of mass need not be displaced (Orendurff, Fujimoto & Smith 1994). Secondly, suspension improves traction by providing a more constant normal force than a rigid system, which also increases time the tyre is in contact with the ground (MacRae et al 2000).…”

Section: Why Use Suspension For Mountain Biking?mentioning

confidence: 99%

Design of hydraulic bottom-out control for mountain bike suspension

Brunckhorst¹

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Engagement with downhill mountain bike engineers revealed a key opportunity to improve mountain bike suspension fork design by addressing 'bottom-out" from harsh impacts. Bottom-out causes damage to components, poor control and discomfort to the rider. This design thesis encompasses simulation, design, manufacture and testing of an adjustable bottom-out damper. The device increases damping forces in the final stage of compression. Simulation of the design demonstrates advantages over existing means to prevent bottomout since greater control over the response is possible with fewer performance trade-offs. The prototype damper was designed and built from existing suspension componentry and custom manufactured parts to integrate with an existing suspension fork. The prototype was validated by testing on a bicycle for a typical impact which yielded results in line with predictions. Specifically, the damper decreased compression amplitudes by up to 20% and settling time by 27%. Tyre contact with the ground was extended by 0.24 seconds for the given impact and variation in normal force was reduced by one third resulting in improved traction. This translates to a more controlled mountain bike, greater predictability for riders and potentially higher speeds in downhill mountain bike racing. The design was successful in controlling for bottom-out and improves mountain bike suspension performance. Further validation is warranted to consider future production of the design. Many thanks must go to Nigel Reeve, of Canyon Factory Racing Team, who provided the initial inspiration for this project, guidance and access to the mountain bike industry. I would like to thank Professor Paul Meehan for his supervision from vague initial idea to the completion of this thesis. My heartfelt appreciation goes to my parents for their support and encouragement during this thesis, engineering degree and my life. Finally, I can't thank my fiancée Rachael enough for her love and belief in me to complete this work, even when I was sure I had bitten off more than I could chew.

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985 the Effect of Mountain Bike Suspension Fork Stiffness on Impact Acceleration Characteristics

Cited by 3 publications

References 0 publications

Vertical stiffness of bicycle frame and its influence on rider comfort

Vertical stiffness of bicycle frame and its influence on rider comfort

Valores de impacto no corpo do judoca ao ser projetado pela técnica Ippon-Seoi-Nage

Design of hydraulic bottom-out control for mountain bike suspension

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