presta valve extensions/extnders?

[02GF74]

I didn't dream this up, they do exist ???

I have deep section rims and my vittoria presta valves, 32 mm (says so on the box ) are too short.

Do these extensions screw on the the short thread for the valve cap?

Does one leave them on the tyre or just fit them to pump up the tyres.

And where to buy them, assuming there are such things?

 

[numbnuts]

http://www.wiggle.co.uk/p/cycle/7/SRAM_Presta_Valve_Extensions/5360039912/

 

[andy_wrx]

Or http://www.chainreactioncycles.com/SearchResults.aspx?Search=valve+extender

Or http://www.wiggle.co.uk/s/cycle/7/valve_extender and http://www.wiggle.co.uk/s/cycle/7/valve_extensions

Or http://www.probikekit.com/advsearch.php?x=0&y=0&AQUERY=valve+exten

etc, etc

Dunno, like you I've never used them.

My understanding was that they were for use on very deep carbon time-trial type rims, where you screw-out the valve core, screw the extender onto the end of the valve on the tube, then screw the core back into the extension and fit the whole lot onto the wheel.

But don't see why you couldn't do this on more 'normal' but deeper-section alu rims - note how the extensions come in different lengths so you'd just pick a sensible size.

They'd be permanant-fit, not for use just to blow-up the tyre and then remove, as basically all they are is an alu tube with a screw-thread at each end : you need to remove the valve core from the tube and attach it to the end of the extender.

Obviously you need tubes with the removable valve cores, which your Vittorias probably are - does it say on the box ?