Tyres Valves and Patches
Doris, my much loved bike, got her first puncture, so I changed the tube at the side of the road, changing my mind about a possible long walk home after about 500 meters. I finally got home to receive an email from Prudential ride London Marketing team on how to fix a flat! Ironic or what!
Armed with a bowl of water, half inflated tube, patches, glue, chalk and a marker pen, I set about mending the slow leaky puncture. The spare tube, that was fitted at the roadside had a different type of valve, so I read up in the Internet and learn something!
There are two types of valves in common use for bicycle tires:
Schrader valves are the same as the valves used on automobile tires. They are common on less-expensive bicycles, particularly those with wide rims and tires. Schrader valves are also sometimes called “American” or “automotive” valves.
Schrader valves have a removable valve core, which may be unscrewed with a special wrench that is often found on better valve caps. They have a spring-loaded valve mechanism. There is a small pin in the center of the valve opening which must be pushed in to put air in (or to let air out.) Before the introduction of the Zéfal HP pump in the 1970’s, there was no portable pump that would do a decent job of inflating high-pressure tires with Schrader valves, which led to the popularity of:
Presta or “French” valves. These are smaller in diameter than Schraders. This makes them a bit lighter, and allows a smaller hole to be drilled in the rim (desirable for very narrow rims). Presta valves are used on most high-performance bicycles, and all tubulars. Presta-valve inner tubes come with valve stems of different lengths — longer ones, for deep-section æro rims.
Presta valves don’t use a spring, but they have a captive knurled nut to hold the core tight. Before you can pump up a Presta tube, you must loosen this knurled nut. It is also a good idea to tap the end of the pin, to break the seal loose, because they are sometimes sticky. After inflating the tube, you should re-tighten the valve nut to keep air from escaping.
I’m proud to say Doris still had air in the back wheel, I can fix a flat! It’s all for a good cause