Originally Posted by
EPOisDope
I
I'm surprised by the comment that running 65-70 PSI up front / 75 PSI on the back on a set of 23mm tires (26mm actual width) for someone whose body weight is 170lbs / 77kg (6 feet tall / 183 cm) is too much pressure. Is that really the case? I thought I was pushing the limits of pinch flats, although I've had none to date. I run latex-tubed clinchers - had bad, messy experiences with tubeless! Also, another person recommended 28mm tires at 60 PSI front / 75 PSI back, which is only 5 PSI less up front, and the same on the back. I've always wondered if you ran an identical tire pressure with 2 different width tires, 23mm vs 28mm in this case, would they absorb bumps equally, or would the wider tire be more compliant? A 28mm GP5000 probably wouldn't fit in this case, but just wondering.
I always forget to add that you have to make sure your pump gauge is accurate which they typically aren’t. I’ve seen pumps off by as much as 15psi when 5psi matters big time to the ride quality.
When Zipp was trying to get carbon wheels right for the cobbles in the Spring Classics, they kept shattering rims no matter what the pressure. Then they hooked up all their pumps to a manifold with a calibrated gauge and they found the pump gauges were as much as 12psi off. That was the difference and from then on they could accurately vary inflation and not destroy rims. Things then made sense.
5psi at 60psi is 8.3% and 7% at 70. 5psi is going to make a difference. If your pump was off by 8-10psi you’d be no where near where you thought you were and if erring on the side of reading too low, you would have a very stiff ride.