Originally Posted by
Broodax
I am a very modest bike mechanic. I can change or patch a tube, set derailleur limiters, and I think I tried to true a wheel without ruining it once.
My wife's bike had a flat after a ride this week. The whole ride we didn't notice, but the next day it was entirely flat. I pumped it up and could hear and feel air escaping next to the valve stem (not out of the stem, it continued even when the stem was covered/plugged). I replaced the tube, no big deal. I assumed that the tube had been compromised around the valve stem hole in the rim or pinched, etc.
I inflated the tube after I had swapped it out, thinking I could patch it to be a spare again... and it just holds air now. It has no leaks. What the...
What kind of valve are you using? If you don't screw the presta down all the way it can seep air. I had a friend give me some tubes he thought failed and they were presta with replaceable valves that had come loose when he was taking the caps off.