Dual Valves?

rockyash

Likes Dirt
If anyone finds out the goss on running dual valves post up.

Scott Beaumont is running dual valves on his 2011 World Champs bike, but is tight lipped about reasoning.

Two tubes so if you get a flat, your wheel will stay reasonably inflated? Dunno?

dualvalve.jpg
 

hazza6542

Eats Squid
Trying to figure out how they could fit two in, is there a chance maybe it's a tubeless setup with an inflated tube in also?
 

HAR

Likes Bikes
Yeah I saw that but no one is saying anything.

Running 2 tubes seems odd because surely it would be heavier and roll worse than say just one heavy DH tube and even a half inflated tyre is going to ruin your race run. There's also the possibility that you pinch flat through both tubes at once anyway. It's the World Champs so there's no real need to do damage control for points, is getting 30th on a half inflated tyre really that much better than 50th on a flat, especially if it is slower rolling to start with anyway.

I thought they might be running one standard tube and then the other is a UST valve, so there effectively running a UST set up with some added protection against burping the tyre and losing air that way. Although neither really looks like a Mavic UST valve.

Either way they've got everyone talking so it could just be a brilliant marketing idea :D
 

spinner

Likes Bikes and Dirt
I thought they might be running one standard tube and then the other is a UST valve, so there effectively running a UST set up with some added protection against burping the tyre and losing air that way. Although neither really looks like a Mavic UST valve.
:D
That sounds like it. Only thing I've heard about this is that they are running tubeless (one valve) and using an inflatable internal beadlock (the other valve).

I have no other info I'm afraid , but I know that some 4WD and moto people use them.
 

Welshy

Likes Bikes and Dirt
The GT mechanics ran the same thing on Hannah's bike at the US champs, where it was explained within limit.

One valve is for a UST conversion kit which isn't inflated. The second valve is for a lightweight tube. The rationale is that if they are to pinch flat the air from the broken tube will inflate the sealed tyre and lead him to an unimpeded run.
 

RangaRMX

Likes Dirt
Pretty sure Welshy is onto it.

Running a normal tyre + tube setup - the other valve is for adding sealant, thus having the sealant inside the tyre but outside the tube - if they were to pinch flat the air would just stay inside the tyre and they'd be able to (hopefully) keep on the pace and finish in a respectable time.

The only reason I can see for them not running a complete tubeless setup is so they can keep the pressures low: too low with tubeless and the tyre will be easy 'burp' out some air if they slightly dislodge the tyre from the rim.
 

Josh Seksy

Likes Bikes and Dirt
I'd agree with Welshy,

I've actually done a similar thing before, just to experiment.

I used a non-ust tyre (furious fred) on a ZTR Olympic wheelset.
Basically I fitted the tyre, filled with some selant, spun it to get it spread evenly, then fitted a superlight maxxis tube.
It worked to a degree, i did loose a bit of air when I pinch'ed, but thats because i don't think it leaked with enough pressure to seat the tire.

Before you ask why...
It was a road&mtb event, so obviously you needed a fast lightweight tire, with enough tread to ride ST, me being a big bloke, I wasn't going to take any chances!

-Josh
 

flamshmizer

Likes Dirt
I'm just guessing but is it an attempt to balance the wheel?
Probably not, every rim i've owned the valve has been oposite the seam, so the pin and weld probably compensate for the valve stem. I reckon those people who run no valve caps actually throw the balance of their wheel out :p

Also the valve stems are off centre relative to the other. Would be interesting to know the story.
 

CP

Likes Bikes and Dirt
You're all way off. It's so they can pump the tyre up twice as fast.
 
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