The simple way to ensure that you don't get caught without a spare inner tube for your deep section Aero rims. 
These simple but functional lightweight retro-fit adaptors will convert a standard length Presta Valve into a usable XL valve.
The clever Woodman designed exterior profile allows for most press-on high pressure pumps to inflate without slippage.
Simple to fit:
Threads onto standard type Presta valve as a normal valve cap would do, and features an internal hex-key recess to fully tighten.
To install, release the knurled Presta valve lock 2/3s of the way along it's spindle - as you normally would to be ready for a pump to be used, and install the extensions onto the valve.
(Existing air pressure will naturally keep the valve closed and air tight - as it does with other types of valve - and pump pressure will open the valve to inflate.)
Features:
Lightweight, precision CNC alloy.
Anodised Black or Red finish
Size options: 48mm or 72mm.