Presta valve stem pulling out of tube

[greywolf]

Has anybody else suffered this? In the old days the valve stem had a large flange at the rubber end, buried in the tube; nowadays they seem to trust the bond between rubber and the small stem base. I use adapter sleeves in any rim that is meant for Schraeder valves, but failure has occurred with proper valve hole drilling anyway. I have noticed it with 700 and 26 inch tubes and several brands. Probably a symptom of the cheapest of three quote syndrome.

[Danneaux]

Yes, I surely have!  In fact, a string of six tubes -- by different manufacturers, purchased at various times and in different countries -- all failed on one of my tours last year.  The failures weren't a result of rough handling. poor pump technique, over-tightening the retaining nut or a sharp-edged rim hole.  They just didn't appear to have ever been fully vulcanized at the tube-valve interface (see pic).  Most pulled free as I unrolled the tube to inspect it.  I now inspect all tubes prior to any trip, taking particular care to tug firmly on the valves.  I also go to the trouble of test inflating them and then rolling all the air out so they can be repacked.  The problem seems to more frequent than in the past.  REI here in the US seems to have inadvertently stocked a number of Novara tubes (mfd. by Kenda) with porosities and pinholes, according to recent user reviews on their site.

Best to check everything at home first, though it surely is a bother.

Best,

Dan.

[greywolf]

Thanks Dan,
I'm surprised there are not more people with the same problem - they probably think it is something they have done.
Like you, I carefully inspect each new tube, trial inflate, deflate, cover in talc powder, and roll up for storage. I pack the things in thin plastic freezer bags (so they don't rub together with toolbag tools and get injured that way), so you can imagine how pi..ed I get when I discover this sort of defect has managed to slip past me - usually I find out on the road.
It's not really the cost that offends, but the darned nuisance of it all.
Thanks for your input.

[Danneaux]

Greywolf,

I've taken to carrying a bolt-on Presta valve, salvaged from an older Michelin tube that was probably manufactured in the late-1970s/early-1980s.  It has already saved the day when yet another vulcanized valve stem pulled out.  It has been years since I've seen a bolt-on stem; it'd be a nice repair item for someone to make available.  The only real drawback is they should be considered for emergency use only; the nutted type was designed back in the day when rims were wider and had a channel-section rather than the box design.  The nut at the base of the valve makes for a bit of a lump in a modern rim and is probably the reason why we no longer see them available for sale.

Best,

Dan.