Review on Continental Bicycle Tubes Race 28 700x20-25 S42 Presta Valve 42mm Bike Tube Super Value Bundle - Pack of 5 Conti Tubes & 2 Conti Tire Levers for Optimal Performance by Dan Venegas

I HATE these tubes! In fact, I think it would be more accurate to say I hate these valves. First, they stick like crazy, making it almost impossible to get the air to move. I attach a floor pump, push it down and the pressure jumps to 140psi. Of course, this is not tire pressure, but pump pressure, since no air gets into the tires. I removed the pump, tried again - same thing. The only way to inflate these things with air is to squeeze the valve 3-4 times to release them to allow air to enter. I was actually considering putting some chain lube on the valves, but I'm afraid that would make problem number 2 worse - the stupid valve core comes out half the time you remove the pump. I've even gone as far as buying one of those wrenches to tighten the valve core but it doesn't help. Yeh! Ooooh disappointed! Sooooo... I don't inflate my tires before every ride anymore because there are days when I just can't pass the 30 minute test. If it passes the compression test, I'll call it good. I'm sure this leads to suboptimal pressure on some rides, but honestly it's better than spending the first hour of every ride cursing the stupid pipes!