Hi,I was wondering why, for example, bike wheels all have (more or less) the same radius. Is it the result of optimizing the laws of physics? I know, for example, that larger wheels cause lower rolling resistance, which is energetically profitable. But would even larger wheels be even more profitable, or is there a limit? And why are car or train wheels smaller?Kind regards, and please support your answer with references to laws of physics.Bib-lost
Bicycle wheels are sized according to the average size of the people using them. Kids have shorter legs than average sized adults and tall people have even longer legs. The wheels are geared to the sprocket so that normal pedaling pace results in reasonable speed. Automobiles have wheels of somewhat different sizes to vary the ground clearance of the vehicle. IDK about RR
The short answer is yes, wheel size is based on optimizing the traits desired. The reason different things have different wheels is that there are multiple factors to consider, including (but not limited to): rolling resistance, traction, cost, weight, size (there can be limitations on size imposed by various factors), material strength, etc. How a wheel is designed depends on its application. To give you an example: Compare train wheels with bike wheels. Bike wheels need to be light weight and have good traction. For train wheels, they need to be extremely durable and have low rolling resistance. Based on these requirements, bike wheels use minimal materials and rubber tires, while train wheels are robust metal and no rubber.
