Right then... I had a random flat on the way home last night, but the tyre holds air, which is making me suspect the valve... It's a pretty old one too. Now, last time I changed a valve I had a bolt-in one to fit, which was dead easy. But all the ones I have now are of the large rubber variety, much like this:
http://ourworld.compuserve.com/homep...rtyrevalve.gif
So... Never fitted one of these, haven't a clue what I'm doing. I'm assuming it fits from the inside, so that air pressure forces it in not out, is there any knack to fitting or is it just force?