unworthy1

A slight thread hi-jack but I bought in bulk a large supply of butyl presta tubes with smooth brass stems and green dust caps when they were really cheap (on sale) and slowly working thru the stash (mainly using on flipper or giving away to friends). One thing that kept coming up is reports that there were mysterious flats and I just chalked it up to "oh well, cheap is cheap, you/me get what you/me paid for"!. Turns out in most cases these bargain Asian made tubes came with REMOVABLE presta valve cores, which many folks have never seen before. They were not tight as installed from factory and most loosened up in normal pump on-and-off so they eventually did not hold air and most folks tossed the tubes. Turns out all that is needed is a firm (but careful) twist tight of the cores with small pliers and they are good to go. Another little detail to watch for if you are buying unfamiliar brands of tubes.

ThermionicScott 

Good point @unworthy1. I’ve become a big fan of Schwalbe tubes over the last couple years, and those sometimes need a little tightening, too. No big deal once you know about it.