's Forum Archives - General

Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )

Question regarding valve extender(5 posts)

Question regarding valve extenderanzoni
Jan 6, 2004 1:22 PM
I recently bought a used set of Cosmic Carbone SSCs. I use 36mm valves with extenders. In this setup the tubevalves are always "open". My question is: can I deattach the extenders when I have the tirepressure I want, or will they leak without the extenders during riding? The have to be open all the time since they are hard to reach by hand.

Question BackScot_Gore
Jan 6, 2004 1:37 PM
Why don't you donate your 36mm's to a friend and buy 48 or 60mm's and do away with the extenders altogether ?

I carry an extender in case I need a tube from a friend (or stranger) that's not a long valve. Mines just a tube that fits over the presta valve and dosn't seal the valve in any way. I've never had cause to use it but I've assumed I'd need to leave the valve open and would likely experience some degree of pressure loss because of it. 100+ PSI will go a long way to keep Presta valve closed, but you're going to experience some pressure loss.

My thoughts

Answer regarding valve extenderChen2
Jan 6, 2004 1:48 PM
Buy some tubes with 60mm stems then you won't need extenders. Carry an extender for emergencies if you run out of the 60's. I use Performance Ultra Lite tubes with 60mm stem on my Cosmic Carbones. They are dependable and cheap. I have to use a lock ring to pull enough stem through to inflate the tube then I remove the lock ring and take it with me. There are also 80mm stem tubes that are easier to use but the stems are too long and weigh too much.
My Carbones are clinchers. If yours are tubular you've got a different problem.
re: Question regarding valve extenderAkirasho
Jan 6, 2004 2:19 PM
... if you're using generic open valve extenders, you could remove them after inflation... the valve core in the tube's stem is doing all the work... but the question is why?

as long as your valve cores are in good shape... they won't leak... in the so called open position, the air pressure from inflation is what closes it... cinching down the valve core nut is more for protection against debris... or that one in a million occurance when some road hazard might knock it open... thus deflating the tube (again, probably not a huge amount unless the strike on the core was catastrophic).

True, many times you can find tubes long enuff to obfuscate the need for extenders... but sometimes not. If you need to use them, along with carrying a spare... you might also carry a short piece of brake cable (soldered at both ends)... to actuate the valve within the extender... this would allow you to deflate a tube without removing and/or fingering around for the core.

FWIW, I do run some serious deep section rims that still require some form of extender... and also run 650C deep section... sometimes, a shop might not have the tubes on hand... but ya still gotta ride... that's why they contine to sell extenders!

Be the bike.
I had to add extenders with a Shimano R-535 wheelset...The Walrus
Jan 6, 2004 2:36 PM
...since no one seemed to make larger tubes (for 'cross) with long stems. As it turns out, even though the valves are permanently open, I have less pressure loss with these wheels than any others that I have. Go figure....