For generations, the standard way to learn how to ride a bicycle was with training wheels or a tricycle. Given the benefits of balance bikes, why did it take so long for them to replace training wheels? There are plenty of other examples in which overlooked solutions that involve subtraction turn out to be better alternatives. Leidy Klotz, an engineer at the University of Virginia, noticed that minimalist designs, in which elements are removed from an existing model, were uncommon. A number of open questions remain, such as whether the bias against subtractive solutions generalizes across cultures and if it exists in childhood or develops over time.