Challenge 42mm Presta Valve Extenders

There are two primary types of valve extenders on the market, and these from Challenge are the "Good" type that RideCX recommends for cyclocross use for their simplicity and reliability. 

Order qty "1" gets you two valve extensions, enough for a complete bike. They weigh almost nothing, include the key/tool needed for installation, and will outlast the wheels and tires you install them on. Each is 42mm long, which combined with the height of the original valve, is tall enough to be accessible even with deep carbon tubular wheels. 

NOTE: to use this superior type of extender, your tubular tire (or inner tube) must have a removable presta valve core. If the core is fixed and can't be removed, this extender won't work (the vast majority of high quality tubular tires and inner tubes have removable cores).

Read on for info about the two types of valve extenders commonly offered if you are interested in the technical details: 

• The first is the style where the original valve core is removed, replaced with an extender, and then the original presta valve core is threaded back in on top of the extender. This type (like these from Challenge) seal reliable, are easy to inflate and close since they keep the traditional presta valve nut on top, and work well as a permanent solution on deep tubular rims where the original valve is buried under the deep rim and hard to access. 
  
  
• The second type (we don't sell or recommend these) simply threads on top of the original valve, which you must leave permanently open. These can leak and stick, and can be impossible to fix if they fail, since the original valve on a glued tubular is buried under deep tubular rims. RideCX recommends avoiding this type of extender.