Am I the only one that calls these dork nuts?
I was very pleased to find this presta valve-stem nut in my parts bin. No idea where it came from, but I’m certain I didn’t spend $2 on it*. The first time I tried to find this thing online, I found $5 prices, which was a funnier link.
I might actually pay $2 for this, since it lets me put a presta tube securely into a schrader-drilled rim. My SON wheel is drilled for schrader valves, because the builder and former owner is an avowed enemy of presta valves. Wade, of Vulture Cycles, points out that schrader valves are found everywhere in industrial applications, and presta valves are only ever found on bicycles. Where they suck.
They do suck, too, which is why dork nuts even exist. I used to leave them off my valve stems to save weight and rattliness. I started using them when I had several tubes fail at the stem, especially on my mountainbike.
Fat guy, fat tubes, low pressure, and the tube starts to creep inside the tire. The stem starts angling over, and stresses out the base where it attaches to the tube. Pretty soon it’s an irreparable leak.
All that said, I still wanted to put a presta valve into this schrader-drilled rim. It’s easier than drilling out 9 or 10 rims and buying all new tubes. Or even pulling the stuck-in tubes out of the IRC Mythos and WTB whateveritis and switching them. The one I pulled off the Sachs Automatic already had a tube happily mated in, and tire-swaps are a lot easier if the tube is stuck in the tire.
So I was pleased to see that this unusual dork nut was specifically made to fit exactly into a schrader valve hole and hold a presta valve securely.
Here’s what Jobst Brandt has to say about schrader vs presta valves (sheldonbrown.com).