From time to time, I’ve fiddled with tire pressure settings on my bike, but have settled in at a psi that I think works for me.
The 23 mm tires that came with the bike listed a max pressure of 115 pounds. I used to pump them to 105, for no particular reason, except that 115 seemed like it would give me a really hard ride — just a guess on my part. When I switched to 25 mm tires, I reduced the pressure to 100 pounds for awhile, but lately I’m back at 105 again.
I was influenced by the Sheldon Brown post which says the load tires must support dictates the pressure. Since I weigh roughly 210, the 105 psi per tire made sense to me.
But now, I’ve come across something else. An article from Bicycle Quarterly says the optimum tire pressure is that which results in a “tire drop” of 15 percent. Tire drop is the amount of compression in a tire when it bears weight. According to the article, anything more than 15 percent reduces your speed. If your tire drop is less than 15 percent, your ride will be less comfortable.
A graph accompanying the article shows tire pressures for different rider weights and different width tires. Turns out that I’m pretty close to where I ought to be, but there’s a wrinkle: the tires are supposed to be pumped to different pressures. On a road bike, the weigh distribution is 40 percent front, 60 percent rear. Yipes! In my case, that means my front tire would be inflated to only about 85 pounds, and the rear to 125.
I’ve gone with lower pressures on the front before, and wound up with a pinch flat for my trouble. So while I find the tire drop article interesting, I don’t think I’ll be making any drastic changes in my tire pressure any time soon. What’s your take?