This is a timely post for me in that one of these stems failed on my rear two days ago when i was re-inflating my tyres coming off dirt roads back onto sealed, STRANDED not a freaking thing i could do, however able to phone my brother who lucky for me lived an hour away and has a pick-up. We eventually got the bike to a shop on closing time, whipped the wheel off and the bloke pressed the bead in with a tyre change machine cut the old valve stem out, pressed the new and i was back in action. I do all my own maint. and strive for reliability and longevity and this failure disturbs me in that such a simple thing can leave you as well as dead in the water. Spent some time that night checking out you tube for ways to fit a new stem on the road and never found anything really convincing. Further searching the net turned up the angled metal bolt on stems that seem to be popular. Yesterday i spoke to a bike tyre fitter , his opinion is that the oe rubber items rarely fail and that a new rubber stem fitted at every new tyre change would guarantee no failures. Went on to say that in his opinion the metal units were a waste of money (and he sells them). Curious to hear anybody's take on this whole topic of broken stems, possible roadside fix, metal stem????