Valve extenders

Richard_P

Just got a 2nd hand set of Mavic Cosmic Carbone clinchers, but the valve extenders are different to each other. If you unscrew one the tyre stays up, if you unscrew the other, the tyre deflates.....so I would like to get some matching slightly lighter ones.

So how do the various types work ? Any help and advice would be appreciated.

schlepcycling

Having a valve extender screwed onto the valve shouldn't have any bearing on whether the tyre stays inflated or not that's caused by the air pressure inside the tube pressing on the inside of the valve, that's why you need to unscrew the the little nut like thing and press it in to deflate the tyre.

I recently got a pair of HED deep ssection wheels with a 60mm rim depth and the guy at HED told me to keep the valves permanently open and then just screw on the valve extender when I need to as the air pressure inside the tube will keep it up.

Do the tubes have removeable valve cores? and are you accidentally unscrewing one of those when you unscrew the valve extender that would cause the tube to deflate.

Richard_P

Schlep...thanks for the info.

I'll take the tyre / tubes off the wheels tonight (if I get time) and check out the situation.

I've also managed to get hold of some valve extenders for my LBS. These simply look like some tubes with threads on the inside bottom, and outside top....so it looks like they should simply screw onto the existing valves, so long as the screw tops on the base valve are left OPEN....

...guess I'll find out soon enough as to whether they'll work OK (or not)....

Eddy S

One type of extender just screws on to the valve (you have to leave the core undone) and the other type requires the removal of the valve core, the extender is fitted and then you put the core in to the extender.

My own preference is for the latter. I think that they work better, are easier/more reliable to pump up properly. The basic screw-on type can be a ‘mare to pump up especially if the core is stuck or dirty.

The only minor thing to watch out for is that you will have to buy tubes with removable cores such as Conti, Schwalbe or Vittoria if that is the solution you go for.

Richard_P

Eddy,

The extenders I've got state "Must Use removable Core" so I guess they're your preferred option....

...I guess I'll need to see what tubes were supplied when I bought the wheels.

Richard_P

Well, just found out why I got two different types of valve extender when I got the wheels....one wheel has an inner tube with a removable vave and the other tube has a fixed one.

So, I've now changed the fixed one for a tube with a removable valve so both wheels have the same tubes, extenders and tyres....and I've still got a spare inner tube with a removable core too (as well as the original inner), so it's now sorted.

Thanks for the help and advice. I've never used valve extenders before, and was quite bemused to find that there were different types in existence.

John Stevenson

To keep things nice and confusing, Topeak does a third type that has an internal rod with a widget that grabs the top of the valve, so you can open and close it without removing the extender, and without replacing the core:

http://www.topeak.com/2007/products/min ... xtenda.php

schlepcycling

John,

Would the Topeak ones solve the almost impossible to inflate problem that I have with the straight forward barrel type extenders. I screw them on then attach the track pump but don't get the normal needle moving around the gauge as the pressure increases it sort of jumps up a bit then starts to 'fall back' the tyre is actually inflating but it's difficult to tell what pressure the tyre is at. I suppose this is why people go for the removalable core type?.