Whoever posts last is best

[agricola]

You're thinking of the Doppler Effect, similar to that of when the noise of a bike engine sounds like a higher pitch (frequency) when it's coming towards you, but lower when it's going away, ie that NEEEEEEOOOooowwmmmmm sound, even though, when you're on the bike, the note doesn't change.

Similarly the colour of the light is blue shifted when it's coming towards you (or you're going towards it) and red shifted when you're going away from it, even though, again, from the point of view of the light itself, the frequency is constant.

So, by that logic, if you're on a bike that's overtaken another bike, the colour of the bike you've passed will be shifted towards the red, meaning that actually red is the *slowest* colour

QED!