There are two main types of bike tube valves – Presta and Schrader. Here is what they look like.
As you can see, the Presta valve is more slender than the Schrader valve. Pretty much all bikes sold in the U.S. before the 1980′s came with Schrader valves. But with the advent of the 10-speed bike – the very popular Schwinn Varsity comes to mind - road bikes rims were outfitted with Presta valves. So one way to remember the difference between the two valve types is:
In oher words, the Presta valve is the more “modern” of the two valves. Note that the Presta valve has a removable inner core and that the rider has to open and close the valve by twisting the tiny little lock top. The Schrader valve has less mechanics involved, and usually bikers will seal a Schrader valve with a plastic top cap. Schrader valves are the type used for cars, and if you ever need air at a gasoline station, the air compressor will have a Schrader end fitting.
Many valve types have come along since the invention of the pneumatic tire but for bicycles mainly Presta and Schrader remain in use. The Presta valve is the more slender of the two and is slightly more cumbersome to use, having a lock nut instead of a spring to ensure closure. However, these two features have kept the Presta valve in use on many bicycles.
In the past, sports and racing bicycles used Presta valves because they are slender and enabled racers to inflate tires with a simple pump with attached chuck (pump head) and no hose. Presta valves are easier to pump than Schrader, because they have no valve spring to overcome. Although a valve depressor for Schrader valves could alleviate this, it would require a check valve, impractical to house in lightweight pump heads.
The small diameter of the Presta valve requires a smaller hole in the rim, whose size is important for narrow rims where cross sectional strength of is significantly reduced by a stem hole. In narrow rims, clincher tires also leave insufficient space between tire beads for larger Schrader valves.
In contrast Schrader valves are more robust, universally used, and have an easily removable core. Spring closure makes them simpler to use because one needs only to press the inflation chuck onto them at an automobile service station. For hand pumps, a screwed or lever chuck provides the valve depressor. The depressor not only makes inflation easier but is necessary to read back pressure in the tire.
Although Presta valves have been made with removable cores, demand is so small that they are uncommon. Removable Presta cores can be identified by two wrench flats on the coarse valve cap threads.
For more information on these two bike valve types, see: