When Alessandro Ballan is flying down a French mountain road, he's not thinking about his valve stems... but you should think about yours.
(Photo: Yuzuru Sunada)
1. World speed record holder John Howard was drafting inside a fiberglass box attached to an 800-horsepower Porsche endurance racing car on the Bonneville Salt Flats at well over 100 miles an hour when his tires started losing air. After a brush with death, Howard’s team discovered that the wheels were rotating so fast that the inertia was depressing the Schrader valve cover in the stems. Sealed caps were the quick fix, but had he been using Presta valves, Howard could have used the safety nut to positively seat the valves and gone on to his 152.2-milean- hour record-setting run the first time. The internal mechanism of Presta and Schrader valves are almost identical— except for the little knurled nut on top of the Presta version that ensures an airtight seal by pulling the tapered valve against its seat inside the stem.
#2 - Some mechanics silence clacky valve stems by surrounding it tightly with a square of black duct tape.
2. Most of us accidentally get the Presta valve aligned slightly off when we glue a tubular or install a tube in a deepdish wheel. This is good, because it forces the stem to one side and eliminates the devastatingly annoying “tick tick tick” that will occur when a perfectly centered valve rocks against the rim with each revolution of the wheel. Applying thin shrink tubing (buy it at Radio Shack) or a few turns of electrical tape will stop the racket—and it’s best to do this trick before mounting the tires.
#2 (cont.) - AG2r La Mondiale’s solution is to pre-wrap the stem with black electrical tape.
3. Removable valve cores are in every Schrader valve, but are relatively new to Presta types. Always buy tubular tires with removable valve cores so you have the opportunity to inject sealant inside should you develop a leak or want your new tubular to last longer than a mayfly in June. Same goes for road tubeless valve stems—you can mount the tire dry and then remove the valve core to cleanly inject the sealant later (thus sparing your living room carpet).
Up close: The Presta valve (L) is locked down with the knurled nut, while the Schrader stem is spring-loaded.
4. If you do use a removable valve core, you can take advantage of Bontrager’s valve stem extension (about 12 bucks). Using the supplied plastic wrench, remove the original valve core and install it on the extension. Then screw the extension onto the valve stem. Now you can access the valve from the outside of the wheel.
#5 - Use a snack wrapper to seal a leaky valve.
5. Ever change a flat and end up 18 miles from nowhere with a leaky valve extension? Using your teeth or a pen knife, cut a thin strip from the wrapper of a gel package or energy bar and roll it up (about one and half turns) inside the threads of the extension or around the end of the valve stem. Carefully screw the extension onto the stem and it will seal it.
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