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Old 07-05-20, 12:16 PM
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Join Date: Dec 2007
Location: San Jose, California
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Bikes: 2001 Tommasini Sintesi w/ Campagnolo Daytona 10 Speed

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Originally Posted by cyccommute View Post
2 psi per day is about the average for the diffusion rate of air out of a bicycle tube. You wonít see bubbles because the air is coming out at the molecular level through the bulk rubber. The diffusion isnít linear so you lose more at higher pressure than at lower pressure. But, generally, I expect to have to pump up bicycle tires on a daily basis.

Bottom line: If the tire goes flat overnight, thatís a puncture. If it only drops a little (<10 psi) overnight, thatís just diffusion and you shouldnít worry about it.
You should change your sig:

"Your Daily Dose - Common Sense Rx"

5000+ wheels built since 1984...


1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:

Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
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