Most Latex tubes have externally threaded valve bodies that enable you to lock the valve firmly to the rim. This prevents the valve from depressing into the rim (when attaching the pump head for inflation) which can cause the tube to herniate at the base of the valve.
Deep rims require valve extensions, and I have never seen one that is fully externally threaded, allowing use of the retaining nut. If you have the correct length of valve extension, there is usually just enough exposed for the pump head. Thus, if your wheels have sat unused and are low on pressure, it is very difficult NOT to depress the valve extension when adding air, and then risking tube failure at the valve base. IMHO, this problem was exacerbated when Vittoria changed their tubes from the large oval grommet at the valve base to the small round one - one of the reasons I switched to Challenge tubes.
I've tried threading some extensions with a 6M x 0.75 die, but the material is very thin and easily self destructs.
Anybody?
Deep rims require valve extensions, and I have never seen one that is fully externally threaded, allowing use of the retaining nut. If you have the correct length of valve extension, there is usually just enough exposed for the pump head. Thus, if your wheels have sat unused and are low on pressure, it is very difficult NOT to depress the valve extension when adding air, and then risking tube failure at the valve base. IMHO, this problem was exacerbated when Vittoria changed their tubes from the large oval grommet at the valve base to the small round one - one of the reasons I switched to Challenge tubes.
I've tried threading some extensions with a 6M x 0.75 die, but the material is very thin and easily self destructs.
Anybody?