Originally Posted by
kingston
I use a formula because I have 13 bikes with 8 different tire sizes and need something to aim for when I pump up the tires before a ride. It's certainly better than guess-and-check with random PSI's.
Why would it be a guess. You have years of experience and should know what works well for you on what road surface on what size tire and bike.
There is nothing random about the guess. Certainly not anything more random than the formula not knowing what the road surface is. If the number given is supposed to optimize ride comfort and/or speed.
I do lower my tire pressures when I'm going on routes that have a rougher road surface. No one like being beat up by chip seal for 10 or more miles. Is chip seal all you people have ?