Originally Posted by
Miele Man
Here's a quick method to determine if tire pressure is too low to prevent pinch flats. Take the bike onto a street and roll the tire up against but not over the curb. Press down hard on the bike (i.e. handlebar for the front wheel) and see/feel how much the tire deforms. If you feel the rim hitting the curb then you know the tire pressure is too low to prevent a pinch flat.
Cheers
That could be too low, depending on bike speeds. I don't get pinch flats from potholes or bad railroad track crossings. I have gotten a few from hitting an unseen sharp edged piece of gravel, out on an otherwise smooth road. Each time, I was going downhill, 25 mph or higher. Those same rocks I can ride right over at 15 mph can pinch flat at fast speeds. So watch the downhills!
Pressures: at 170 pounds, I go as low as 60 psi front and 70 psi rear on 28mm tires. But I usually run 68 to 70 front and 80 to 85 rear. Either set of pressures feels fast and efficient. I like the (slightly / moderately?) reduced chance of pinch flats with the higher pressures.