Bicycle Mechanics - valve extender leaking?

I've got some tubular Zipp 303's that I had to use the screw on valve extender with. I used teflon tape on the threads when I installed them as shown in the instructions... My question; after about 3 days the tires have leaked all of their air.

I've already mounted the tires so this def. makes everything harder; any ideas of where it's leaking..? is there a core extender that i can buy? does this work better?

The extender is outside the pressurised part of the tube, so sealing only matters while you are inflating the tire. The pressure in the tire seals the valve. Look for the leak in the tube. It may have been pinched on installation, the rimstrip may not be properly covering all the holes, or there may be a sharp edge on the hole in the rim for the valve.

The extender is outside the pressurised part of the tube, so sealing only matters while you are inflating the tire. The pressure in the tire seals the valve. Look for the leak in the tube. It may have been pinched on installation, the rimstrip may not be properly covering all the holes, or there may be a sharp edge on the hole in the rim for the valve.

It's a Tubular... no tube pinched, no rimstrip..

The extender is outside the pressurised part of the tube, so sealing only matters while you are inflating the tire. The pressure in the tire seals the valve. Look for the leak in the tube. It may have been pinched on installation, the rimstrip may not be properly covering all the holes, or there may be a sharp edge on the hole in the rim for the valve.

Note that OP said 'tubular', which means no pinching on installation, no rimstrip, etc. I've had tires go mysteriously flat overnight on bikes using valve extenders, only to be pumped up in the morning and last for months. I think that's it's possible to install the tube at a slight angle (especially with tubbies) that may put some pressure on the presta valve to allow air to leak out.

Another consideration is that your tires could have latex tubes which will always bleed air very quickly. Before doing anything drastic like taking off your tubulars, I'd check with the manufacturer to see what the tube material is and also try to pump it up again to see what happens.

Note that OP said 'tubular', which means no pinching on installation, no rimstrip, etc. I've had tires go mysteriously flat overnight on bikes using valve extenders, only to be pumped up in the morning and last for months. I think that's it's possible to install the tube at a slight angle (especially with tubbies) that may put some pressure on the presta valve to allow air to leak out.

Another consideration is that your tires could have latex tubes which will always bleed air very quickly. Before doing anything drastic like taking off your tubulars, I'd check with the manufacturer to see what the tube material is and also try to pump it up again to see what happens.


Thanks, They are vittoria open corsa evo cx. Pumped them up twice but still leak down.

When I installed the extenders I screwed the core all the way out maybe get something to fit inside extender to tighten it back up after inflating?? Seems like there has to be a better way than this.

I see Tufo Makes some kind of valve extenter that actually comes with a longer valve; anyone have any experience with these? do they work on any tire or just tufo?