Is there an optimal cycling speed in the rain?

TL;DR: I thought there was. There isn’t, unless there’s a tailwind. In vertical rain, faster is always drier. Motivation Link to heading I was cycling home yesterday in heavy rain and started wondering about the right speed. Slower means more time getting drizzled on. Faster means more rain per second on my front. It felt like there had to be a sweet spot. The setup Link to heading Picture rain falling at speed $v_r$, with $\rho$ drops per cubic metre. I cycle at speed $v$ over distance $D$. Let $A_t$ be the area of my head and shoulders (top), and $A_f$ the area of my chest (front).