Presta valve problem

Lustrum

Hi all, I'm new to road bikes and have recently acquired a Scott S50 speedster. Now I bought one of these mini-pumps that fits both schrader and presta valves figuring it would be enough just to keep the tyres topped up. Except that the pump does not seal around the presta valve on the bike!

Can anyone explain what I might be doing wrong, or is it possible I just bought a rubbish pump and should chuck it? I've since reverted to the old school way of a long pump and presta adapter, and that's doing the trick for the moment but I'm annoyed at having bought something that doesn't work

dubmess

You probably need to flip around the internals in the head of the pump.

Check where it would connect to the valve, you should be able to screw the top off. Inside there should be the rubber seal and if you get that out there should be another plastic bit under that, they should come out pretty easily.

You basically need to flip them both around and refit them.

The rubber bit has a wide gap at one end for schrader valves and a narrow one for presta, have the narrow end facing out.

Similarly the plastic bit should have a small protrusion that would depress the nipple in the valve of a schrader tube, flip this around and there should just be a hole the presta valve would fit in to.

Reassemble and away you go!

I realise I've made that sound a lot more complicated than it actually is...

Lustrum

I've got that done thanks, the problem I'm having is that the presta adapter doesn't seal around the valve itself. So when I open my valve and pop on the pump, all the air immediately escapes and I can't pump the tyre back up because all the air is just being pumped down the side of the valve.

I hope that explains what the problem is!

coastwatch

Hope I'm not point out the obvious, but a lot of mini pumps have a small lever that actuates a seal / clamp around the valve.

chewed

I'm having the exact same problem! I have a pump with a clamp lever. But when I unscrew the presta valve and attach the pump the air escapes! Now I've no air in the tyre. And, as I'm pumping air in it's just escaping at the same time! Is it my pump?

jinkypolly

Normally these lever clamps go two directions depending on what connection you are using, make sure your pushing it the correct way. On my pump I have to push the lever away from whatever end I am using.

chewed

Yes, it's the same on my pump. You press the lever away from it.

the tyre is now completely flat and I just can't get any air into it!

Qualitymark

This may help http://www.youtube.com/watch?v=Ehf6HL0aLTc

chewed

Thanks for that. I got it sorted. It was my pump! I borrowed a neighbour's pump and it worked. Time to buy a new one