As you know, the other day I got a set of Mavic CrossLand wheels for my late model mountain bike. The CrossLand wheels are designed for Presta-valved tubes (or tubeless tires). Up to now, I had more conventional American wheels on my bike, which meant I was using Schrader-valved tubes. (I found a page that shows photos of Presta and Schrader valves side-by-side, in case you don’t know what I’m talking about.)
I guess the guys at Knapp’s Cyclery think I’m very knowledgeable about cycling gear, because they didn’t ask me if I knew how to put air in a tube with a Presta valve. I knew that my floor pump had a double-sided nozzle assembly for both Presta and Schrader, so off I went.
The first time I tried to check my tire pressure, I unscrewed the Presta valve cap on one of my tires, attached the Presta end of the pump’s nozzle assembly, and tried to pump air. The air went nowhere. The gauge on my pump skyrocketed past 100 pounds per square inch. That wasn’t right. I tried disassembling the nozzle. Nothing seemed wrong with it.
Finally, I studied the Presta valve itself. I noticed the locking nut, the function of which I did not know, and thought, “Maybe if I unscrew this, the pump will work.” That did the trick.
Let this be a lesson to me. I didn’t learn everything there was to know about bikes by watching OLN and maintaining two mid-range, American-made mountain bikes. I’m learning, slowly. But, this is why I’ve tried to build as much expertise in electronics, computers, and software as possible.