How much air goes from the tire to the pump when you plug it on the valve?
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I am trying to figure out how much air my tires lose between rides by using my floor pump's pressure gauge. I was always told it could be between 0 to 20PSI, but I have never verified.
The thing is that there is a loss of pressure inside the tire as soon as I connect the head on the valve (physics ) so the reading is not accurate. I am trying to figure out how much pressure is lost during the connection. Google wasn't helpful. Just in case, I know I can buy a gauge to read the pressure directly at the valve.
Has anyone ever wondered / found the answer or am I the only bored cyclist in the world who has time to think about these things? I know it will vary based on the length of the pump's air hose and surely a few other factors, but there should be a known average, right?
The thing is that there is a loss of pressure inside the tire as soon as I connect the head on the valve (physics ) so the reading is not accurate. I am trying to figure out how much pressure is lost during the connection. Google wasn't helpful. Just in case, I know I can buy a gauge to read the pressure directly at the valve.
Has anyone ever wondered / found the answer or am I the only bored cyclist in the world who has time to think about these things? I know it will vary based on the length of the pump's air hose and surely a few other factors, but there should be a known average, right?
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I guess I have to drill out all of my bikes wheels and convert them to Schrader because the minutia of Presta valves is to complex for me to grasp. I'm not worthy.
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Good idea. I worked for a trucking company, that for a while, transported helium. 40 foot trailer with about 20 long tanks on it. It weighed 5000 LESS when it was fully loaded.
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Thing is that if the attachment is depressing the valve stem, then you also loose some air pressure from the tire when you detach the hose or can lose a lot unless you really pull it off fast without any fumbling, not always easy to do.
Also, sticky valves is when you fill up at much longer intervals, like on bikes with bigger tires that run at lower pressures. I top up my 700x23s once a week but really should do that every three days or two if I was more picky.
Last edited by vane171; 04-20-21 at 09:30 AM.
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Doesn't matter. That and the pressure gauge on the pump will never be the same as a hand pressure gauge because none of them are very accurate. What's more important is precision, not accuracy.
Pick one gauge and one pressure you like and stick with it.
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You should always push the pump hose attachment on the valve only partly, not all the way that it may go (that is, unless you the good pump as you pointed out). It is attached wrongly when the air escapes into the pump hose. When that happens to me (my pump is not of the good sort), I re-attach the hose, sometimes need to do that twice before it is seated properly. But I agree that some pumps are constructed better way to prevent that to happen. With those other ones, you need to have a good sense not to push the hose head on the valve too deeply.
Thing is that if the attachment is depressing the valve stem, then you also loose some air pressure from the tire when you detach the hose or can lose a lot unless you really pull it off fast without any fumbling, not always easy to do.
Also, sticky valves is when you fill up at much longer intervals, like on bikes with bigger tires that run at lower pressures. I top up my 700x23s once a week but really should do that every three days or two if I was more picky.
Thing is that if the attachment is depressing the valve stem, then you also loose some air pressure from the tire when you detach the hose or can lose a lot unless you really pull it off fast without any fumbling, not always easy to do.
Also, sticky valves is when you fill up at much longer intervals, like on bikes with bigger tires that run at lower pressures. I top up my 700x23s once a week but really should do that every three days or two if I was more picky.
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That's typical forums for ya.
I love the guys who exclaim "This is not that interesting". Ok fine, you're not interested, you can leave without bothering to say anything.
I love the guys who exclaim "This is not that interesting". Ok fine, you're not interested, you can leave without bothering to say anything.
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Makes me wonder if there should be a rule about not commenting on the form/manner, but rather on the substance.
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I am always surprised when people ask such silly questions. Makes me wonder how they function and get through day to day life.
Of all the forums I'm a member on (I participate in some fishing, kayaking and car enthusiasts forums) this place takes the cake with the craziest comments and questions I've ever seen. One thing I've learned on this forum is that common sense isn't so common. I'm left scratching my head 70% of the time.
Of all the forums I'm a member on (I participate in some fishing, kayaking and car enthusiasts forums) this place takes the cake with the craziest comments and questions I've ever seen. One thing I've learned on this forum is that common sense isn't so common. I'm left scratching my head 70% of the time.
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I am always surprised when people ask such silly questions. Makes me wonder how they function and get through day to day life.
Of all the forums I'm a member on (I participate in some fishing, kayaking and car enthusiasts forums) this place takes the cake with the craziest comments and questions I've ever seen. One thing I've learned on this forum is that common sense isn't so common. I'm left scratching my head 70% of the time.
Of all the forums I'm a member on (I participate in some fishing, kayaking and car enthusiasts forums) this place takes the cake with the craziest comments and questions I've ever seen. One thing I've learned on this forum is that common sense isn't so common. I'm left scratching my head 70% of the time.
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Funny post. Get a gauge.
I inflate my tires, verify with gauge. All my floor pumps read differently vs the gauge. Specialized Air Tool, Lezyne steel, and the third, just got can't remember the model.
Lexzene always reads low so I inflate a bit more. Check with gauge. Checking with my gauge doesn't lose air vs attaching pumps. Though, if I am real careful and steady attaching, no air loss. Pull head straight off after inflation, just a hint of a hiss. No biggie.
I inflate my tires, verify with gauge. All my floor pumps read differently vs the gauge. Specialized Air Tool, Lezyne steel, and the third, just got can't remember the model.
Lexzene always reads low so I inflate a bit more. Check with gauge. Checking with my gauge doesn't lose air vs attaching pumps. Though, if I am real careful and steady attaching, no air loss. Pull head straight off after inflation, just a hint of a hiss. No biggie.
FYI, I think no matter how careful you are attaching your pump, you'll lose some air into at the least the pump's hose -- I think that's unavoidable, unless you're talking about a minipump that attaches right at the base of the pump and has no hose.
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