damnable

Greetings,
I went to pump up my tires just then and found that both those little screw on valve covers have gone. Did I forget to put them back on last time...who knows, but BAM! they've gone.

So that begs the question, just how important are they? How likely are the valves stems to get damaged if I don't have them on? Should I presume that my LBS would stock them, or even autoshop?

The valves are Shraeder so if I am in trouble without them I can always borrow some off my sisters car until I find somewhere to buy them.

CommuterRun

Don't sweat it. The dust cap on a Shrader valve does just that, keeps dust and dirt out of the valve. However, if there's pressure on the tire nothing's going to get into the workings of the valve anyway. Before adding more air to a tire you can blow out any grit that may have gotten into the valve by just depressing the valve core.

I wouldn't worry about it, but you should be able to find dust caps, cheap, at any auto parts store. You can even get them shaped like bullets, dice, or little skulls, etc.

Rowan

Tyre joints should have heaps of them, so many that you might be able to beg a couple for nix. They do keep dirt out of Schrader valves. There was a thread in the Bicycle Mechanics forum not long ago that identified a tiny bit of grit as the cause of a deflating tyre.

GlassWolf

mine are all presta, but on the road bike I don't even bother. on the MTB, I use them to keep mud and grime off of the valves so if I have to air up or air down on a trail I'm not wiping up mud with my shirt to clean up the valve stem.

BarracksSi

I try to use them on both Presta and Schrader valves. Yeah, the seal keeps stuff out while riding, but it's when you stick a pump on there that can push junk into the seat of the seal.

curbtender

Next time your at the gas station go look by the air pump, usually 2 or 3 sitting around...

wahoonc

Or any mall parking lot...I bet there are thousands of them

FWIW the only time I haven't run valve caps was when I was running tubulars, if one came unglued and rolled you didn't want the valve cap to cause it to hang up coming off the rim. The caps do an excellent job of protecting the valve assemble from mud, and grit.

Aaron

Retro Grouch 

All of our bikes are presta valve. I keep valve caps on my rolled up spare tube to keep the stem from accidentally puncturing the tube while it's in my saddle bag. Once the tube is on the bike I don't care.

Doug5150

I have a pal at the local auto-parts store, and he warned me NEVER to buy the cheap "custom" valve caps.

The reason is that the cheaper caps are all made of aluminum, and valve stems are brass. They make them out of aluminum because it's silver and won't corrode visibly, but aluminum will suffer galvanic corrosion in contact with the brass stem, which tends to cause the cap to seize on the stem.

The only METAL valve caps you should buy are ones made of brass.
~

BarracksSi

Almost forgot about those..

Besides the galvanic corrosion, they have a separate rubber seal. After long enough, it'll degrade, separate from the cap, and get itself stuck inside the valve stem.

I've got some nice-looking anodized red valve caps that are completely worthless. Plain plastic is better.

wahoonc

I have a fairsized collection of stainless steel ones that are typically used on heavy equipment FWIW if you are checking your air pressure on a regular basis I don't think galvanic destruction/corrosion is that big of a deal. YMMV I do happen to have a source for some nice machined brass ones at about $10 a pair

Aaron

operator

Valve caps = 100% unecessary. Good way to add weight to your bike as well.

StephenH

The dust caps are about 90% cosmetic. Years ago when fixing flats on dump trucks (think super dusty all the time), we never used those things and you very seldom have problems from it. It just slows you down when you go to air something up or check the pressure. They're not intended or needed to physically protect the valve from anything.

Saintly Loser

Yeah, they're unnecessary, but I have some super-cool machined aluminum ones anodized in a shade of green that exactly matches my bike's paint. I saw them in a store in Japan and couldn't resist.

By the way, Japanese bicycle shops are completely full of really, reall cool stuff.

SweetLou

It doesn't beg the question, but they are not very important. On presta valves, they are not needed at all. Though I keep mine on. I figure they might just possibly somehow keep something from hitting the nut and damaging it.

If you live in a cold climate, the road salt and chemicals can damage the brass and seal of the valve, the cap will help to prevent this. Also if you do develop a small leak, a tight fitting valve cap will help. My recommendation is if you find one, put it on. But don't go out of your way to get one.

I-Like-To-Bike

And the weird harmonics from the out of balance wheel!! Oh the horror of that extra gram of weight!

wahoonc

That is supposedly balanced out by the CSPC reflector that should be mounted on the opposite side of the wheel.

Aaron

MMACH 5

My bike has steel cap with a core tool and a regular, plastic cap on the other wheel.
I think I got it with an old touring bike.

The only time I had to use it was on my wife's car. It had a defective core.

dobber

I though that's what spoke cards were for?

Sprocket Man

I have a 2 sets of gold anodized valve covers that I got from a store called Mont Bell in Tokyo. When I saw them, I had to buy them because they were just too cool to pass up.