The front tire on my road bike has a puncture. I have a Schwinn pump that has two outlets to accomodate regular valves as well as schrader valves. While the tube is inside the tire, I am able to attach my pump to the schrader valve on this bike and fill the tube with air (of course, thanks to the puncture, it promply empties) -- I have no idea how the pump figures out it's supposed to pump air from the schrader outlet and not the other one.
To repair the puncture, I took the tire off the rim, and removed the tube. Now, when I try to pump the tube with air, the pump only pumps through the wrong outlet (the schrader has been opened to let in air). Weird.
Quick correction: This bike has a presta valve not a schrader valve -- sorry!
Premal P. Vora said:
The front tire on my road bike has a puncture. I have a Schwinn pump that has two outlets to accomodate regular valves as well as schrader valves. While the tube is inside the tire, I am able to attach my pump to the schrader valve on this bike and fill the tube with air (of course, thanks to the puncture, it promply empties) -- I have no idea how the pump figures out it's supposed to pump air from the schrader outlet and not the other one.
To repair the puncture, I took the tire off the rim, and removed the tube. Now, when I try to pump the tube with air, the pump only pumps through the wrong outlet (the schrader has been opened to let in air). Weird.
On 13 Oct 2006 11:45:23 -0700, "Premal P. Vora" <[email hidden]>
Quoted message said:
The front tire on my road bike has a puncture. I have a Schwinn pump that has two outlets to accomodate regular valves as well as schrader valves. While the tube is inside the tire, I am able to attach my pump to the schrader valve on this bike and fill the tube with air (of course, thanks to the puncture, it promply empties) -- I have no idea how the pump figures out it's supposed to pump air from the schrader outlet and not the other one.
To repair the puncture, I took the tire off the rim, and removed the tube. Now, when I try to pump the tube with air, the pump only pumps through the wrong outlet (the schrader has been opened to let in air). Weird.
Any suggestions? Thanks in advance.
-Premal
Dear Premal,
Push the tube against the base of the tire valve to provide resistance:
| ___ |____
_________ ^ | push tube upward against bottom of valve
<[email hidden]> wrote: Push the tube against the base of the tire valve to provide resistance: (clip) ^^^^^^^^^^^^^^^^^ The first thing I would do is try it on the other tire (that is still inflated) to make sure it is working okay. Presta stems usually are held to the rim by a nut, so when you apply the connector, the stem is firm. With the tube off the rim, I'll bet you are not inserting it far enough to actuate the mysterious linkage to close off the Shraeder opening. This is consistent with what Carl V. said.
<[email hidden]> wrote: Push the tube against the base of the tire valve to provide resistance: (clip) ^^^^^^^^^^^^^^^^^ The first thing I would do is try it on the other tire (that is still inflated) to make sure it is working okay. Presta stems usually are held to the rim by a nut, so when you apply the connector, the stem is firm. With the tube off the rim, I'll bet you are not inserting it far enough to actuate the mysterious linkage to close off the Shraeder opening. This is consistent with what Carl V. said.
Dear Leo,
Sorry, I wasn't clear--the idea is to seal the base of the Schrader or Presta valve and provide back pressure.
Twin-head air chucks work by air resistance. If there's not enough back pressure to trip the valve (an empty inner tube), the wrong outlet may stay stubbornly open.
Usually, pressing the tire and tube flat against the base of the valve provides enough back pressure to trip the annoying valve and make it notice which outlet you want to use.
Ryan Cousineau explained this gentle push-the-tube-against-the-base trick that provides back pressure and cured me of my more enjoyable habit of giving the recalcitrant twin-head chuck a brisk whap with the handiest tool to wake it up.
