so I've taken some pictures of the valve on my bike tyre (if you zoom out they look clearer...), below. Basically, it's a new bike and I have no experience around these things. The pump I have doesn't fit onto the valve, because it gets stopped by the nut in the middle before it can attach - it's like the pump head is too deep for the valve. Does that make sense? But when I take the metal nut in the middle off, obviously the valve then falls out - but if I hold it in place it can pump the tyre up (showing that the pump is the right type) - but as soon as I remove the pump the valve then falls out and all the air comes out of the tyre again.
I bought the bike in Europe (Slovenia) if that changes anything.
Thanks for any advice on what to do here.
(My pump is http://washford.scene7.com/is/image/Washford/128234)