Join Date: Jul 2000
Bikes: 1959 Capo; 1980 Peugeot PKN-10; 1981 Bianchi; 1988 Schwinn KOM-10;
I think you are using a Presta valve in a Schraeder-drilled rim. Try putting a thin metal washer over the valve stem, to keep the tube from bulging through the rim. The inner diameter of the washer should just barely exceed the outer diameter of the valve stem, and of course the outer diameter should slightly exceed that of the hole in the rim.
"Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
Capo [dschaw'-poe]: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger, S/N 42624
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1981 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069