Schrader time

     Everyone uses schrader valves. Yes, everyone. I know you are thinking you would never have a bike with schrader valves, you are presta all the way. But, your suspension shock and fork use them. Your car has them at all four corners, one for the fuel injection, and two on the AC system(Your home HVAC has them as well) There is even one on your water supply if you have a well.
     They are everywhere and with good reason. The schrader valve is a spring loaded poppet valve that makes it very easy to get a measured amount of gas in or out of a system. It was patented by August Schrader(most likely developed by his son George) in 1891.
     It would take another five years to develop the schrader valve cap. That's right, plastic cap, five years of R&D. Remember that next time you have trouble coming up with a plan of action.
     We have the schrader valve thanks to the bicycle. When August saw the popularity of pneumatic tires coming out of Europe he saw a need for a tire valve. Which is a little odd, because they already had a valve, other wise they would have been flat tires coming out of Europe. That valve was the presta. I have not found much on the history of the presta valve except that it seems to have been appropriated from the steam industry.
     The schrader valve has some advantages over the presta valve. They are serviceable, the core can be removed and cleaned or replaced(Some presta valves have a removable core). The valve is spring loaded and does not require pressure behind it to stay closed. Because the valve is spring loaded and the air chucks and gauges have a fitting the depresses the poppet, you can get a more accurate reading of pressure.
     A disadvantage is the hole required is slightly larger than for a presta valve. If you have a very narrow rim strength could be compromised. I feel this may have been an issue a hundred years ago when rims were made of wood or rolled from steel sheet. I have never seen a rim fail at the valve hole(Where it was not run over by a truck or tossed off a mountain side)
    You should use the valve cap. It took five years to develop, there must be some crazy technology in there somewhere. The practical reason is that it keeps crud out of the valve. If you have a little dirt in the top of the valve and then pump up the tire, some of that crud is going thru the valve and some of it might get trapped between the poppet and seat, creating a leak. You can remove the core and clean out this area but it is simpler to just keep it clean.
      The valve caps should be considered part of your suspension. The schrader valve is great for holding pressure but a rear shock at full compression can experience a spike over 3000psi. The beefy cap with its built in seal keeps that in the shock. If you lose a cap, stick a plastic one on to keep the valve clean, but replace that with a proper sealing cap as soon as possible.
     I am not going to go in to tire pressure here, that is a whole other post, but if you are concerned about your pressure, be sure to use a quality gauge(not a stick gauge). Digital gauges work best and are the most consistent, but a good dial gauge can give a decent reading. Be sure to use the same dial gauge each time so the readings will be consistent(There can be a big difference from gauge to gauge)

From my collection(of junk). Made in 1922, still works.