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why have a nut on the outside of inner-tube valves?(5 posts)

why have a nut on the outside of inner-tube valves?cbloom
Oct 9, 2002 9:53 PM
What's the point of that nut on the outside of inner-tube valves? (the one you screw down to the rim) I can never seem to get it to tighten enough to stop rattling, and it would seem that the pressure in the tube is pushing the valve out of the hole anyway, so why bother with this nut at all?
If your tube is flat, it holds the valve stem in place whenscottfree
Oct 10, 2002 5:07 AM
you attach the pump head. So you don't shove it down in the hole. (Although road valve stems are so long you can usually get a grip on the bugger with your fingers to hold it in place. More of a problem with MTB tubes. The Schraeder valves are shorter & nubbier).

Bottom line is, there's no reason for that nut except convenience.
re: why have a nut on the outside of inner-tube valves?BowWow
Oct 10, 2002 3:07 PM
Yup, purely for convenience when filling the tube. Back in the days whe I was wrenching dirt bikes I'd remove both the nut and the valve cap. This helped preserve the tube if the tire went flat while riding and the tire spun on the rim. With the valve stem bolted down, a flat almost always ripped the stem from the tube, but with nothing stopping the stem from slipping through the rim, it generally preserved the tube.

The danger of ripping the stem from the tube is minimal on bicycles, so now I back the nut off and use it to lock the cap on. It keeps the nut handy for reinflating, and still gives me the peace of mind with slipping flats on rims...

Throw the nut away.Kerry
Oct 10, 2002 4:33 PM
Those nuts cause more problems than they "solve" and one of the best tubes on the market, Michelin, doesn't have a threaded stem. If you need to work the pump head on a flat tube, just push the tire down to the rim on the back side of the valve. After the tire is pumped up, the pressure in the tire will allow engagement of the pump head. The threaded nut's most typical use is to rip the valve stem out of the tube.
re: why have a nut on the outside of inner-tube valves?sprokit
Oct 14, 2002 3:02 PM
There may be some purpose on a mountain bike where you are running low tire pressures but on a road bike go nutless. I run Michelin tubes and they have no nuts or even threads for a nut. I prefer a smooth threadless valve stem it is easier on the valve stem chuck of your tire pump.