Inner tubes

[Uncle Stretch]

Ok I heard the answer once before ,but for some reason I forgot. Why do bicycle inner tubes loose air. Does putting air in them start some kind of deteration process. It seems like if you aired the dumb things up and they held air for a while that they would keep holding air.

 

[2manybikes]

Re: Inter tubes

I think the valves leak. Presta valves hold air lots better than schrader valves becuase you tighten the valve up against the seat. Schrader valves rely on the spring.
It also could be our old pal osmosis :mrgreen:

 

[user 135]

Re: Inter tubes

You are probably failing to park your bike with the valves up. If the bike sits around idle, the air eventually stops moving and ends up in the bottom of the tire. If you park with the valve stems near the bottom, the valves may not be able to handle the additional air and will leak.

 

[Ratfink1962]

Re: Inter tubes

You are probably failing to park your bike with the valves up. If the bike sits around idle, the air eventually stops moving and ends up in the bottom of the tire. If you park with the valve stems near the bottom, the valves may not be able to handle the additional air and will leak.

Ah yes, I think your onto something. You might try having them filled with Nitrogen, I bet that will fix it... plus you'll get better mileage :lol:

 

[xddorox]

Re: Inter tubes

What I've been told over the years is that the tube itself is actually porous to a point and that would explain why you have to check your air pressure on a regular basis. But now I'm curious and I will have to experiment with the valve idea.

 

[Uncle Stretch]

Re: Inter tubes

What I've been told over the years is that the tube itself is actually porous to a point

Seems like that is what I can recall was the reason they leak, but if they really are ...Then how do they hold air in the first place.

 

[Bicyclerick]

Re: Inter tubes

Tubes are porous as are most rubber or latex products. Have you ever blown up a balloon and the next day it has went down? Its the same thing with an intertube, some stay up longer than others but they all eventually go down.

 

[user 135]

Re: Inter tubes

Where did the humor go? Scientific explanation. Oxygen molecules are smaller than Nitrogen thus leak out of the microscopic pores sooner. Air is %78 nitrogen, 21% Oxygen, and 1% other.

http://www.getnitrogen.org/why/index.php

 

[2manybikes]

Re: Inter tubes

Where did the humor go? Scientific explanation. Oxygen molecules are smaller than Nitrogen thus leak out of the microscopic pores sooner. Air is %78 nitrogen, 21% Oxygen, and 1% other.

http://www.getnitrogen.org/why/index.php

Yeah, like I said our old pal osmosis :mrgreen:

 

[user 135]

Re: Inter tubes

Here are some good explanations.
http://www.kenkifer.com/bikepages/humor/air.htm

 

[thatismytruck]

Re: Inter tubes

You are probably failing to park your bike with the valves up. If the bike sits around idle, the air eventually stops moving and ends up in the bottom of the tire. If you park with the valve stems near the bottom, the valves may not be able to handle the additional air and will leak.

If you keep your bicycle in a temperature controlled environment at lab temps (20-25 degrees C), rotate the wheels weekly and change the air bi-monthly one can prevent a reduced pressure. Pure Nitrogen can help but it's hard for you to separate out the oxygen and other. I've just begun experimenting with Helium. Aside from raising my voice a few octaves while inflating the tires, there appears to be little change. Although I noted that I could go over puddles in the road with significantly less splashing.

 

[KZ1000]

Re: Inter tubes

You are probably failing to park your bike with the valves up. If the bike sits around idle, the air eventually stops moving and ends up in the bottom of the tire. If you park with the valve stems near the bottom, the valves may not be able to handle the additional air and will leak.

That makes a lot of sense to me, I have bought many bikes that were hanging from hooks for 20+ years and there was enough air still in them to be able to ride them

 

[Uncle Stretch]

Re: Inter tubes

That makes a lot of sense to me, I have bought many bikes that were hanging from hooks for 20+ years and there was enough air still in them to be able to ride them

Maybe that is like old steel is better than new steel....Maybe old air was better than new air...less polution. :roll: :wink:

 

[user 135]

Re: Inter tubes

Maybe that is like old steel is better than new steel....Maybe old air was better than new air...less polution. :roll: :wink:

Acid rain. That humidity is getting into our tires and eating them from the inside out.

 

[KZ1000]

Re: Inter tubes

That makes a lot of sense to me, I have bought many bikes that were hanging from hooks for 20+ years and there was enough air still in them to be able to ride them

Maybe that is like old steel is better than new steel....Maybe old air was better than new air...less polution. :roll: :wink:

In case you don't understand Uncle, BIKE IS NOT SITTING ON TIRES, NO WEIGHT ON TIRES, HANGING FROM HOOK, TIRES HAVE NO PRESSURE PUSHING AGAINST THEM :roll:

 

[OCD]

Re: Inter tubes

That makes a lot of sense to me, I have bought many bikes that were hanging from hooks for 20+ years and there was enough air still in them to be able to ride them

There's your problem, 20 years ago bicycles used something called inner tubes which hold air much better than these new fangled inter tube thingies. :wink:

 

[onelesspedestrian]

Re: Inter tubes

I think the valves leak. Presta valves hold air lots better than schrader valves becuase you tighten the valve up against the seat. Schrader valves rely on the spring.
It also could be our old pal osmosis :mrgreen:

false. the air itself is what holds a presta valve shut, pushing out from the inside. the threaded nut is just an extra security. I broke that nut off once, when removing the pump from the valve (at 110 psi) and then went for a ride, since I didn't want to fix it just then, as I was already late. the valve held just fine, even at high speed with centrifugal force, until the next fill, at which point the valve shot into the inside, and the tube was trash.

 

[user 135]

Re: Inter tubes

Maybe an upgrade to Stan's Tubeless is order. No need to worry about these pesky tubes anymore.

 

[karfer67]

Re: Inter tubes

i would also think the rubber it's self is porous so it will slowly let air out as well. but i would also be willing to bet the valve is to blame as well. and i can sorta prove my tubes them selfs leak air cause on my bikes with drilled rims they seem to go flat much faster than solid rims.

 

[2manybikes]

Re: Inter tubes

I think the valves leak. Presta valves hold air lots better than schrader valves becuase you tighten the valve up against the seat. Schrader valves rely on the spring.
It also could be our old pal osmosis :mrgreen:

false. the air itself is what holds a presta valve shut, pushing out from the inside. the threaded nut is just an extra security. I broke that nut off once, when removing the pump from the valve (at 110 psi) and then went for a ride, since I didn't want to fix it just then, as I was already late. the valve held just fine, even at high speed with centrifugal force, until the next fill, at which point the valve shot into the inside, and the tube was trash.

Both air pressure and the force exerted by the threads on the valve stem act in the same direction so my statement is not false. The actual ammount of force that the threads exert is more than the the internal pressure.