SlinkyWizard

My LBS installed some tubeless tires on my bike, I had one original presta valve ( a long one ), and lost the other one , I changed tubeless to airless tires , and now going back to tubeless. The guy at the store said he had a short presta valve, and set up my wheels with one long and one short presta valve.

I went to check air pressure in my tires this morning, first the wheel with the long presta valve, locked the floor pump onto the valve, the indicator said 80psi, so pumped to 100psi,

then went to lock the pump onto the short valve, the needle on the gauge said 0 psi, I tried to push down on the pump, and I couldn't, it seemed to be stuck.I took off the pump lock thingy, tried again and same result.

I have never had a problem with the longer presta valves, but I couldn't get any air into the tire with the short valve.

Is there some kind of trick I'm missing, or something I am doing wrong?

Thank you for any advice.

Dan Burkhart 

If the valve is too short for the pump head to mechanically push it open, you have to blow it open with air pressure. It takes considerably more pressure than what is currently in the tire to do this as the surface area on the inner face of the valve is greater than that of the outer face. Try letting some air out of the tire before trying to inflate. If your pump is capable of producing the pressure needed to blow it open, you will see the pressure spike, then hear a pop as the valve blows open and your gauge should then read the pressure in the tire.

Homebrew01

Maybe the valve is stuck. On Presta valves, after unscrewing the lock-nut, I always "burp" it by giving a quick tap to make sure it's not stuck.

Litespud

Agreed - if the valve is the least bit sticky, it can sometimes defeat any pressure you might impose with the pump. I have occasionally unscrewed the the locknut, attached the chuck, and spiked the pump pressure to 130-140 psi to no avail. Once I pull the chuck and push the valve plunger to free it up, it inflates with no problems

bogydave