Before I started training for triathlons, I had not ridden a bicycle in many many years. At the bike shop, I was trying out a new Trek and was embarrassed to say that I didn’t know how to shift! The Shimano shifters were new to me. Equally new were the Presta valves on the tires. I had only ever seen a Schrader valve, which is what you will find on most automobiles and non-racing bicycles.
What is different about the Presta valve?
First, the entire outside of the valve is threaded and comes with a nut. A very thin nut. The nut is used to prevent the valve from disappearing into the wheel while you are pumping it up. They are not required, but can be very helpful. On the flip side, if you are like me and don’t have a clue about them, you will get a blow out trying to pump up the tire. I tightened the nut so that it was tight against the rim. This has the effect of making the tube burst at the connection to the valve.
Second, the Presta valve has to be unscrewed at the top before the valve can be acutated. So, no air will go in or out until this is done.
Third, the Presta valve won’t work with a typical Schrader valve pump! You must have a special pump or get a pump with an adapter. My Target-bought, Schwin floor pump has one.
Lastly, the Presta valves come in different lengths. They work identically, but the longer length valves are made for deeper rims.