Hello,
On previous bikes, I've had clinchers with presta valves and have never had a problem using my "Beto" floor pump to inflate the tyres. On a new bike, I put on wheels with tubular rims and tyres (Vittoria Rally). The problem is, after loosening the nut on the valve and pressing it quickly to let out a jet of air, when I attach the pump to the valve and close the latch, air escapes as I pump. I can fill the tube with air only if I push the pump nozzle onto the valve with one hand as I pump with the other. It's really inconvenient! It's as if the pump nozzle has nothing to grip onto when its lever is fastened.
I notice that the valve is a removable one (two flat sides on the threaded section). I have tried tightening the valve with a pair of pliers (i don't have the correct tool) but it doesn't seem to help.
Might it be the pump that's the problem? Is there something else I can try?
Thanks,