<i>Bicycling Science,</i> 2nd ed.

Whitt, Frank Rowland; Wilson, David Gordon; Duffy, Richard J.

doi:10.1119/1.14329

Cited by 9 publications

(10 citation statements)

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“…The rolling friction coefficient of racing bikes and time trial bikes is 0.0025-0.003 [8,35,36] and 0.0057 [14], respectively. The speed-independent rolling friction coefficient of automobiles is 0.009-0.014 [7].…”

Section: Discussionmentioning

confidence: 99%

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Influence of mass on the speed of wheelchair racing

Fuss

2009

Sports Eng

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Reducing the mass of a racing wheelchair improves the winning time even for relatively small mass reductions over short distances (100 m). In this study, the improvement of speed and winning time on mass reduction was modelled mathematically, the speed profiles of 100 m wheelchair races as well as the rolling resistance and drag area of the athlete-wheelchair system was determined experimentally, and the improvement of the winning time through mass reduction was calculated from the mathematical model and experimental data. For winning times of 30 s, the relative improvement of the winning time is at least equal to the relative reduction of mass. For winning times of 15 s, the relative improvement of the winning time is at least half the relative reduction of mass. A reduction by 1 kg results in an overall improvement of the winning time of about 1-2.3% for winning times of 15-30 s (100-m race). In absolute terms, a mass saving of 1 and 5 kg on a 60-kg system would reduce a 15-s winning time for the 100 m by 0.132 and 0.66 s, respectively, and a 30-s winning time by 0.63 and 2.86 s, respectively. The mass of a wheelchair is the most important parameter for improving the winning time. The influence of the mass on the winning time is 4 or 1.5 times greater than the influence of the rolling friction coefficient, and 4 or 5.5 times greater than the influence of the drag area in a 15 or 30-s race, respectively. These principles should be considered when designing a racing wheelchair.

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Section: Discussionmentioning

confidence: 99%

“…where l R is the coefficient of rolling friction, and m and g are the mass (of the cyclist and the bicycle combined) and the gravitational acceleration, respectively [8][9][10][11][12][13][14][15]. Woude et al [16] applied the same principle to wheelchairs.…”

Section: Dynamics Of Wheelchair Racingmentioning

confidence: 99%

Influence of mass on the speed of wheelchair racing

Fuss

2009

Sports Eng

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“…For instance, if the three efficiencies were the same at 95%, then the total bike efficiency Z would be 0.95 6 0.95 6 0.95 ¼ 0.86. The efficiencies of the bike's bearings and drive train are indeed now close to 98-99% (Burgess, 1998;Kidd, Loch, & Reuben, 1996;Whitt & Wilson, 1982), so that further improvements here are difficult to achieve. However, changing the frame material has given bike designers the opportunity to increase the stiffness of the frame, which has the advantage of reducing energy loss due to frame deflections and vibrations.…”

Section: Effect Of Input Parameters On Performancementioning

confidence: 96%

The impact of technology on sporting performance in Olympic sports

Haake

2009

Journal of Sports Sciences

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To assess the effect of technology on sport, the performance statistics for four disciplines were analysed: the 100-m sprint, pole vault, javelin, and cycling. The concept of a performance improvement index was developed to allow comparison between athletes and between sports with a higher index indicating a greater improvement in the sport. The following performance improvement indices were found: 100-m sprint, 24% over 108 years; pole vault, 86% over 94 years; javelin, 95% over 76 years; 4-km individual pursuit, 35% over 32 years; one-hour cycling record, 221% over 111 years. Around 4% of the index for the sprint was attributed to tighter, aerodynamic clothing, suggesting that general athletic improvement in sprint-type events has been around 20%. Technological developments in simple equipment such as the pole vault or javelin were seen to affect the index by around 30%, while the index associated with aerodynamic improvements in the one-hour record was around 100%. It is concluded that the performance improvement index could be extended to amateur as well as elite sport where distance or time is used as a measure of performance.

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“…For the 30°load case, only one force of 1800N is mandatory with the test cycles of 50000. The obligatory load values of the standard appear conservative compared to the test data shown in the article [44]-a 34-year-old healthy man can generate during 2min on a bicycle power of 200W with a rotational speed of 50rpm. Therefore, he generates a torque of 38.2Nm and considering the crank arm length of 170mm, it translates to the force at the pedal of 225N.…”

Section: Loading and Assessment Criteriamentioning

confidence: 84%

Application of Functionally Graded Shell Lattice as Infill in Additive Manufacturing

Kędziora¹,

Decker²,

MUSEYIBOV³

2023

Preprint

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The presented research article shows a functionally graded lattice as an infill structure in designing a 3D printed mechanical element—a bicycle crank arm. The authors want to answer the fundamental question: whether the functionally graded lattice structures can efficiently improve structural performance and how they can be implemented in real complex components. Intuitively, everyone senses that using such elements must bring profit. A good example might be nature, which commonly reaches for such a solution in the skeletons of animals and humans. Two aspects determine their realisations: the lack of adequate construction and analysis methods and the limitations of existing manufacturing methods. Thus, the authors used relatively simple crank arm design and design exploration methods for structural analysis. The design exploration method enabled us to find the optimum solution efficiently. A developed prototype was created utilising additive manufacturing. One of the 3D printing methods - fused filament fabrication technology for metals, allowed the prototype of a crank arm with the optimised infill to be made. As a result, the authors developed a lightweight and manufacturable crank arm showing the new construction and analysis method implementable in similar 3D printed elements.

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Bicycling Science, 2nd ed.

Cited by 9 publications

References 0 publications

Influence of mass on the speed of wheelchair racing

Influence of mass on the speed of wheelchair racing

The impact of technology on sporting performance in Olympic sports

Application of Functionally Graded Shell Lattice as Infill in Additive Manufacturing

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