Originally Posted by
noglider
I found a flaw with my pump. It has a hose which I screw onto the valve stem. Nowadays, some brand new tubes have valve cores which are not screwed in tightly. I was commuting to work and got a flat, changed the tube, and every time I removed the hose, the valve core came out. I guess I'll check all my tubes before I put them in my tool bag, but I'm not happy about this. I ended up getting back on my route by flagging down a cyclist and using his pump, the kind you just push on and pull off.
Are you talking about the Lezyne Road Drive? If so, I'm not sure what people are doing wrong to unscrew the core. I've been using one since 2013 and never removed a core with it. The only thing I can say is to make sure you take a pair of small pliers and make sure the core is snug, but I've never had to do that with any of my tubes I've used.