Quote:
Originally Posted by RoosterCogset
Well that's interesting.
So, if I understand -- Width As Measured is not important -- use the nominal size?
The max PSI for a 28mm tire per this chart is the 73psi amount, and per Silca's calculator, I come up with the max system weight that a 28mm setup can accommodate is about 130lbs.
So, normally the suggestion is 'use a wider tire'. Ok a 30mm tire per this chart can only be inflated to 65psi. Lo and behold, Silca's calculator indicates that roughly the same 130lb total system weight (ie. 110lb rider) is about the most that fits under this ceiling.
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Tire pressure affects many properties, including comfort, handling, rolling resistance, safety, rim protection, etc. Any pressure recommendation will have to optimize for a particular balance of all these properties. The Silca pressure calculator primarily optimizes for rolling resistance. Josh Poertner of Silca has stated that most people would probably do better with a little lower resistance, for a little better comfort.
Quote:
Originally Posted by Dave
Try the Zipp pressure calculator. I put in 140 pounds to cover my weight with shoes, clothes and other stuff. It only suggests 51.3 front and 54.6 rear. Even 240 lbs comes in well below 72.5, unless thin sidewalls are specified. Then it suggest 72.6 psi for 220 pound rider.
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We don't know what properties the Zipp calculator optimizes for. But is interesting to note that for the same entered values for rider/bike/conditions/etc, the Zipp calculator recommends lower pressure values for hookless rims than for hooked rims. So either the Zipp calculator optimizes for a different balance of tire/ride properties for hookless vs. hooked, or it applies a fudge factor for hookless rims to keep below a set maximum.