Originally Posted by
rekmeyata
In addition to all the above good info, today's tubes no longer use a thick either steel or rubber reinforcement around the valve stem which is the reason for the rise of mini pumps with a hose. If you pumped up the tire before the ride it is possible that you put too much stress on the valve and then after a period of time with air pressure adding to the weak area it simply let go.
By the way I never use the presta valve lock nut that is suppose to hold the stem in the correct location on the rim, but if you have really deep rims then you may need to use it but not because the valve will move but so that you don't have to struggle to get the valve into the hole to add air when it's flat or real low on air.
Haha, leaving off this part that is obviously specified with the tube (tube, nut, and cap) is as old as the hills. The valve nut and cap were not thought to be "essential" enough to warrant the extra "weight". And so started the trend of leaving lock nuts and caps off racing bikes. It was the same sort of ridiculous nonsense that led to decades of 39/53 chainrings (great for racers but the rest of us?) and a complete disregard for helmet safety within the peloton (at least until they were forced to wear their helmets).
Edited to add: there is ample evidence that mini pumps do little damage to valves that are secured with lock rings. If the bike can't withstand the social pressure to forgo using a lock ring, you could carry one in your saddle bag. Haha