Inflating a deflated Presta tube?
 

Any tricks to inflating a Presta valve tube from a completely-deflated state?
Pulled out my bike for first time I a while, tires were flat. When I open the presta valves (unscrew them for inflation) and try to put my Blackburn AirTower 2 AnyValve pump over the Presta valve , I can't get it to inflate: all that happens is I press down on pump and then the pump pops off the valve , it's as if the Presta valve is screwed close but I double-checked it's not. Any tips or tricks to get the Presta valve to start taking in air?

Sometimes the valve can get stuck. After you unscrew it, push it in. That will break the seal and you should be able to inflate it normally.

^^ yup

+1 more.

Only posting to remind you that you'll probably need to "burp" the valve each time before pumping.

A completely deflated tube may allow the valve to be pushed back into the tire so far that the pump head can't get a purchase. If that's the problem, push on the tire tread directly over the valve to keep it sticking out far enough. And, yes, a sticking valve can require huge pressure to open so tapping it with your finger first is often needed.

And that's one of the reasons the stems come with those little knurled nuts that people generally discard.

The Michelin road tubes I used don't even have threaded stems, much less nuts. However, pushing inward on the deflated tire at the position of the stem will support it so that you can get the pump head on. Once mostly inflated, the air pressure supports the stem well enough to attach the air chuck.

At the low pressures with fat MTB tires, the nut is more useful.

As Looigi noted, not all Presta stems are threaded and those nuts serve only that limited purpose. I discard them because the are a nuisance when you do have to repair a flat, both to remove the tire/tube and to reinstall it. Pressing with my thumb is easier.

They also serve to keep the stem in a radial orientation, reducing the risk of tear flats at the stem base.

John,

I respectfully disagree. (partly). While they stabilize the valve when pumping which is in their favor, they can also mask tire/rybe creep by keeping the valve from moving with the tube, increasing shear stress at the base, and eventually leading to base separation.

I vave mixed feelings on these nuts. I NEVER use them on tubulars, but do leave them on loosely on the fat tired commuter so pushing the head on produces less stress on the tube/valve connection.

These days, with the newer crappier design, valve separation is my No.1 cause of flats. I've found it happens most often because of corrosion causeing a bond failure, especially after rain. These days, I'm using an O-ring sandwich on the valve stem, with the nut closing it tight against the rim, and it seems to be helping, but the jury's still on on this,

Do they even make tubulars with threaded stems?

I have tires about a year old and they have threaded stems.