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Discussion Starter · #1 ·
Hey friends!

I just bought my Trek 2100 on a sweet deal at my LBS but I have already had two problems with the back tire in less than 2 weeks. The first thing was the tire went totally flat over the course of 2 days while I was away. No idea why. I took it to the shop I bought it from and they said they just re-inflated it and it was fine. I took it on two rides on back to back days after that so I didn't check the pressure.

Today I went to check my tires and filled my front tire first and it worked perfectly. When I put the nozzle on the rear tire valve i hear a little air leak out and then I flip the lever (which on the front tire worked just fine) and it says my air pressure is 14psi and one pump increases it to 150psi! I have tried and tried but I just can't get it to work. Has this happened to anyone else? Perhaps its something simple that I am missing or maybe the valve is malfunctioning but any suggestions would be appreciated!

Matt
 

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MattofBostone said:
Hey friends!

I just bought my Trek 2100 on a sweet deal at my LBS but I have already had two problems with the back tire in less than 2 weeks. The first thing was the tire went totally flat over the course of 2 days while I was away. No idea why. I took it to the shop I bought it from and they said they just re-inflated it and it was fine. I took it on two rides on back to back days after that so I didn't check the pressure.

Today I went to check my tires and filled my front tire first and it worked perfectly. When I put the nozzle on the rear tire valve i hear a little air leak out and then I flip the lever (which on the front tire worked just fine) and it says my air pressure is 14psi and one pump increases it to 150psi! I have tried and tried but I just can't get it to work. Has this happened to anyone else? Perhaps its something simple that I am missing or maybe the valve is malfunctioning but any suggestions would be appreciated!

Matt
are you unscrewing the presta valve before trying to seat the pump head on the valve? Other than that, you need to push the pump head down harder...you aren't getting any air in and the PSI is showing that fact.
 

· Fat'r + Slow'r than TMB
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If it is a presta valve make sure you press on it first with your finger to release the valve (air will come out) then press down with the pump. Sometimes if the valve it too short it will not get depressed when you go to air it up. Push the pump on and hold it there and then start to try to inflate. My wife has deep wheels and it came with short stem valves ( no idea why) not the long stem. Occasionally, my pump will not get pushed down enough and will not inflate her tire and I am tooo lazy and cheap to switch to long stem valve tubes until they have a hole in them. If that does not fix the problem, again push on the valve and let the air out, now try to inflate with your mouth. If no air goes in then, you have something wrong and need to change the tube.
 

· sometimereader
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Bocephus Jones II said:
are you unscrewing the presta valve before trying to seat the pump head on the valve? Other than that, you need to push the pump head down harder...you aren't getting any air in and the PSI is showing that fact.
In addition, after unscrewing the valve, push the plunger down (just for an instant) to break the stiction that is sealing it.
 

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Discussion Starter · #7 ·
Ok so to answer some questions, I'm unscrewing the stopper. I did the same thing on my front tire and everything went swimmingly! I will try to push harder but also when I press on the valve it releases air so that doesn't seem to be the issue. Thanks for the tips and I will report back!
 

· sometimereader
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jsedlak said:
Ok... stupid question, but how do you inflate a tyre like this?

Apparently it isn't the same as my (old) valves where you just press on and lower the lever to lock it and open the valves.....
For more than you wanted to know: http://www.sheldonbrown.com/flats.html
 

· Cat 6 rider
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MattofBostone said:
Ok so to answer some questions, I'm unscrewing the stopper. I did the same thing on my front tire and everything went swimmingly! I will try to push harder but also when I press on the valve it releases air so that doesn't seem to be the issue. Thanks for the tips and I will report back!
It sounds like you've got the tire valve open now. Now push the pump head down harder on the valve before locking it. When you open it, you should hear a momentary, though quiet sound, and the gauge will read the tire pressure.

The 14psi to 150psi indicates, as previously stated, that you were reading the pressure in the hose, not the tire.

There is a very small possibility that you have a defective valve. You're probably just not getting the pump head down far enough on it.
 

· Resident Curmudgeon
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Sometimes you have to jiggle the pump head a little after you clamp it on the valve. You could try doing this with one hand and pumping with the other. You probably won't be able to completely inflate the tire like that, but once you achieve a good air path, you're good to go.
 

· sometimereader
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jsedlak said:
That says to unscrew it, and then screw it back on so as not to let air out. This is just a secondary tightening of the valve, right? It would be stupid if I had to manually close the valve.......
Schrader valves have a spring that keeps the valve closed (except when high pressure is applied). Presta valves are closed simply by interior air pressure; but that can lead to air loss whenever the valve gets bumped - so you should indeed manually screw down the valve after filling the tube.

To recap: To fill a presta tube, unscrew the valve all the way, tap the top of the valve to break the seal, inflate, screw the valve back snug.
 

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The first thing was the tire went totally flat over the course of 2 days while I was away. No idea why.
Might be a slow leak. There are actually leaks so slow that it can take many days to deflate. Some people just pump them back up again, but I'd rather fix the leak or replace the tube and be done with it. When you have a really slow leak, you can pump the tube up, immerse it in a bucket of water, and you might only see one small bubble form a minute from the site of the leak.

I don't get many flats these days, but of the ones I do, I discover at least as many the day after the ride is over as I do during the ride.
 

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Bleed a little pressure

Happens all the time. Others have said it, tap the valve after unscrewing the inner part. This tap should be enough to actually hear air come out. It is not the lower pressure that does it, it is that the tap breaks the seal that has had hours/days to set, and resists the higher air pressure on the pump to break it lose. The seal also has a bit of a taper which makes it even harder to break lose.

The tap with a small hiss of air is all you need to fix this problem IMO.
 
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