chungachanga

I've had two 700c tubes develop punctures right at the base of the valve stem. I am using a Silca pump. It goes onto the stem easily, but is a little difficult to pull off. However, I don't think I am yanking it side-to-side when I am pulling it off the stem. I was wondering whether putting a little grease on the stem would allow the pump head to go on/off easier, but am afraid of air leakage. Anyone have similar problem? Any ideas?

mrfix

I use a silca pump also, what I do is just slide the chuck over the small part of the valve stem and apply a slight twisting motion as I start to pump, this seals the connection, when I'm pumped up I just give the chuck a slight twist in the other direction and it pops off the stem. I used to do what you are doing and had the same thing happen, after a number of pump related flats I decided to call the manufacturer and find out what my problem was, they were nice about it and explained how the chuck should be used. It works great now that I know how to use it.

sch

This should be regarded as a fatal error due to a manufacturing defect rather than something that you did. The junction of valve and tube should not be so frail as to rupture with the act of placing or removing the pump. Steve

Davet

Check the area around the valve stem hole for sharp edges. If your wheel has the hard plastic rimstrip tape, replace it with Velox rim tape.

MichaelW

Use a small piece of emery cloth to smoothe the edge of the valve hole. I do this with any new rim before I put the Velox tape on.