Very simple question
 

Hello everybody, I'm new to these forums and very new to biking. I have a very simple question that no doubt has been covered here before.

I have a road bike whose tires have presta valves. I've tried pumping them with a floor pump but for some reason they're not filling up? Doing the correct things, taking the valve off halfway and "locking" the pump on, with not much progress. Does the pump have to be latched on all the way down so it is touching the tire, or does it only have to cover the tip of the valve?

Many thanks for your help and comments! Thank you for reading.

I am not sure what you mean in your explanation below by "Doing the correct things, taking the valve off halfway and "locking" the pump on" So lets try this:

1. Remove valve cap.

2. completely loosen the little nub at the top of the presta valve.

3. depress the valve, releasing a little bit of air (if there is air in the tube) to ensure the valve is not sticking.

4. Check to make sure your pump is not configured for shrader valves. If it is, change the configuration so it is for presta valves (if your pump is capable of pumping both presta and shrader valves this usually means the plastic piece inside the pump head should have the nub that depresses the sharader valve facing inward...you usually also have to flip the rubber gasket so the narrower opening is facing outward).

5. Attach your pump and lock it in place.

6. Pump up your tires.

If this does not work, reply to this post and try to describe more accurately what you are doing and what kind of pump you are using.

-j

Are you unscrewing the presta valve stem tip, then tapping the top of it to break the air pressure seal? Then put the pump end on, about halfway down the valve stem, and pump. You may half to flip a lever on the pump end to get it to seal right. Also, you may get some initial resistance until the presta valve opens up.

If the valve stem has a screw-on locknut, make sure it is not preventing (i.e. not up too high up away from rim surface) pump nozzle from completing going on valve. Also, some valve stem without locknut will tend to push back into rim (esp. if tube has little air in it) as you place pump nozzle over it.

Thank you Greenfieldja for your message. I did as you recommended... and took a video of the process... so the frames are below. The thing is... as you can see in the last pic, the pump doesn't seem to latch on all the way, and I can feel a tiny bit (but not all) of air coming out of the head of the pump everytime I pump. Has this got something to do with it? Thanks for your patience guys and I appreciate this is a really elementary issue.

ps the vid was taken by a Blackberry hence it's a little out of focus. x

In the last photo, with pump in locked position, it looks like pump nozzle is backed away and at an angle as well.

I can also see neck of presta valve; appears, nozzle is not fully pushed on. I'd try holding wheel on tire side with left hand as you slide nozzle over valve with right and lock it in place using right thumb.

As bike_boy said, the nozzle isn't pushed enough. If you can't manage to lock it properly, that means your valve stem is too short for your pump, and there it starts to get complicated. From the cheapest to the most expensive option you have :
- try to use a shradder adapter ( 1$), if your pump can inflate shradder...
- change tube for a longer valve stem (4-5$)
- buy a valve extender (4-5$)
- change your pump (30-???$)
Anyway, be cautious with the nozzle being at an angle like that because that little rod at the top is very fragile

Nice Decathlon wheel by the way ;)

Those things do not work with presta (sorry for been in A$$) the main reason im saying it is because of the problem u have right now, second the lock mechanishm sucks because for sure the presta valve will get warped too, what u need to get is a SILCA floor pump nozzle thingy. Take the nozzle u have there out and put the one i'm saying. Still do not understand why they have a lock mechanism when the SILCA has been in the market for the last 60 years maybe and works just fine the 1st time. Listen this old timer, get this!

This is what u need and get an extra rubber washer just in case but dont lose it ok? Look at ebay also, may places have them

http://www.amazon.com/Silca-Presta-V.../dp/B001AYSFNY

ps: do not forget to add a clamp also. U will need it, the silca stuff last years also.
ps1: if you need shradder just buy a car pump one and put the bikes in there. Who gives a darn about shradder anyways :P

Dear All, thanks for your help! I did what Bike Boy said and held the wheel firm whilst pressing the nozzle onto the valve. Seems to have worked a charm! Thank you again and I'm going to take the bike for a spin for the last hour of daylight... Have a lovely week xx

It seems like your pump head is not on the valve far enough. It does not need to bottom out at the rim but it should engage at least 3 to 4mm past the shoulder where the valve stem narrows (where it is currently engaging). Also, as others have suggested, make sure your pump head is going on straight.

If for some reason your pump will not go on further then you need a different pump head if it is a floor pump or a different pump if that is a frame pump.

A really good bike shop should carry a replacement pump head. As suggested by ultraman6970, silca makes a really good one but you can get a good quality brass one that is capable of switching between presta and schrader by swapping the guts around (I have had one on my old silca track pump for years). You will need to cut your old pumphead (chuck) off and use a tiny hose clamp to attach the new chuck...this is assuming you are using a floor pump.

-j

I have been happy with my Silca Pista, (track) pump for over 20 years. they use a rubber gasket that tightens
it's grip around the stem as the pressure in the hose &in its bell shaped end increases..

presta valve stems have a band that is unthreaded that the rubber gasket seals around.


I have a second floor pump for Schrader valve types , It has a thumblock.