Originally Posted by
meanwhile
If orange bikes were that fast, Merckx's bike wouldn't have been fitted with a yellow speed booster strip on the seat tube. (Back then frames weren't strong enough to survive at All Yellow speeds.)
They were actually afraid that Merckx would snap the frame in half before he got up to speed and only an orange bike could survive Merckx's output and speed.
There was something about a non rhyming colour having special properties and the yellow speed booster (actually a braking device) was not used in 1972 as Merckx's bike had no need for brakes.