The maneuverability and compactness of small-wheel and folding bicycles are greatly appreciated. Nonetheless, the performance of these small-wheel bicycles as compared to the big-wheel bicycles has always been questioned. They are often blamed for being less stable, wobbly, or twitchy. It is still unclear how the performance of the small-wheel bicycle designs can be improved. Both small- and big-wheel bicycles are designed with similar ergonomics; therefore, the focus has been on the front steering design. The steering design parameters of 91 big-wheel and 27 small-wheel bicycles were compared, bearing in mind the available front steering design guidelines to understand: (1) the influence of big-wheel bicycle’s frame design on small-wheel bicycles and (2) most common range of design parameters used in current bicycle designs. The analysis showed a strong influence of current big-wheel bicycle design practice on front frame parameter selection of small-wheel bicycles. Furthermore, the self-stability comparison over the most common design range confirmed the lesser stability in the current small-wheel bicycle designs at normal riding speed. However, it was also found that the lesser stability was not the result of small wheels per se, but rather owing to an inadequacy in the current design approach to addressing the complex influence of reducing wheel size and bicycle frame design on its stability and performance. Therefore, an improved design methodology was adopted by incorporating the bicycle dynamics into the current design approach and the front steering design guidelines for small-wheel bicycles have been developed. The guidelines contradict the current small-wheel bicycle design practice, as they recommend steeper headtube angles for small-wheel bicycles. The guidelines were validated with good agreement between the theoretical and experimental results on two prototype 20-inch-wheel bicycles having counter-intuitive steering geometry.

中文翻译：

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为小轮自行车开发改进的设计方法和前转向设计指南，以提高稳定性和性能

小轮和折叠自行车的机动性和紧凑性受到了极大的赞赏。尽管如此，这些小轮自行车与大轮自行车相比的性能一直受到质疑。他们经常因为不稳定、摇晃或抽搐而受到指责。目前尚不清楚如何提高小轮自行车设计的性能。小轮和大轮自行车都采用相似的人体工程学设计；因此，重点一直放在前转向设计上。比较了 91 辆大轮和 27 辆小轮自行车的转向设计参数，牢记可用的前转向设计指南，以了解：（1）大轮自行车车架设计对小轮自行车的影响和（2 ) 当前自行车设计中使用的最常见的设计参数范围。分析表明，当前大轮自行车的设计实践对小轮自行车的前车架参数选择有很大影响。此外，对最常见设计范围的自稳定性比较证实了当前小轮自行车设计在正常骑行速度下的稳定性较差。然而，还发现稳定性较差并不是小车轮本身的结果，而是由于当前的设计方法不足以解决减小车轮尺寸和自行车车架设计对其稳定性和性能的复杂影响。因此，采用改进的设计方法，将自行车动力学纳入当前的设计方法，并制定了小轮自行车的前转向设计指南。该指南与当前的小轮自行车设计实践相矛盾，因为他们建议小轮自行车使用更陡的头管角度。这些指南得到了验证，理论和实验结果在两个具有反直觉转向几何形状的原型 20 英寸轮自行车上得到了很好的一致性。