Engineering:Presta valve
The Presta valve (also French valve (FV) or Sclaverand valve) is a tire valve commonly found in high pressure road style and some mountain bicycle inner tubes. It comprises an outer valve stem and an inner valve body. A lock nut to secure the stem at the wheel rim and a valve cap may also be present.
Name
The Sclaverand valve was invented by Frenchman Etienne Sclaverand and is often referred to as the French valve. Today it is also known as Presta valve.[1][2] Presta or presto stands in the Romance languages for "fast, hurry, immediately".[3]
Description
The outer valve stem is manufactured in various lengths for different applications and has a narrower diameter of 6 mm (0.24 in), compared to Dunlop and Schrader valves, measuring 8 mm (0.31 in). The weakest point of a bicycle rim is usually the hole for the valve stem. The smaller hole for a Presta valve makes it possible to have extremely narrow wheels while maintaining sufficient strength in the wheel.Cite error: Closing </ref> missing for <ref> tag
Valve extenders
.jpg)
Valve extenders can be used to lengthen shorter Presta valves to accommodate deeper and thicker rims, such as those on aerodynamic race wheels. There are two variants of valve extenders depending on whether the Presta core is removable.[4]
Threading
The valve threads for Presta valves follow the ISO 4570 standard.[5] The external threads at the tip of both "threaded" and "unthreaded" Presta valves are 5V2 (#12-24TPI), which measures out to 5.2×1.058 mm,[6] the same thread size as the tip of a Dunlop valve. The external threads on the main body of "threaded" Presta valves are 6V1, which measures 6×0.80 mm.[6]
See also
References
- ↑ GB189709082A Improvements in Pumps for Inflating Pneumatic Tyres and the like.. London: G. F. Redfern & Co.. 1897.
- ↑ "Improvements in Pumps for Inflating Pneumatic Tyres and the like". Europäisches Patentamt. http://v3.espacenet.com/publicationDetails/biblio?locale=de_EP&adjacent=true&KC=A&date=18980219&NR=189709082A&DB=EPODOC&CC=GB&FT=D.
- ↑ "Synonyme". Julian von Heyl (private site). https://www.korrekturen.de/synonyme/Prestaventil/.
- ↑ "Valve Extenders, How To". http://www.slowtwitch.com/Tech/Valve_Extender_How-To_3007.html.
- ↑ "Valve connector". https://patents.google.com/patent/US6631729B2/en.
- ↑ 6.0 6.1 "MARYLAND METRICS -- THREAD DATA CHARTS (26)". http://mdmetric.com/tech/thddat26.htm.
 |  |
