Hot answers tagged

14

The advantage is that it's quicker and easier to get the tube out and tyre off, and you never have to deal with jammed nuts. IME the nut will be wedged unbelievably tight the one time you get a puncture at an inconvenient moment, and you'll end up breaking the valve (if you have pliers) or not being able to get at the hole (if you don't). The problem there ...


13

Inflator heads with Presta fittings let you do this because they tend to (always?) seal down around the stem, not the core. I don't know any other way. I suppose you could also take a spare Presta core from a dead tube, break the plunger out of it to get more airflow, then temporarily install it in your tubeless valves and put your adapter on that. This is ...


12

I prefer having the nut, because it makes pumping much easier, especially road side with a frame pump. I put them on finger tight and then retighten after inflating, and I've never had one jam, or rattle.


11

My conclusion after many years of using not two, but three types of valves is that the best is the one that results most practical for you, acording to type of riding, type of pumping methods available and of course the type of bike/tire/rims you are using. Neither valve type is absolutely better than other, but one of them may result better for your ...


11

As others have mentioned one reason is to make it easier to installed slime/sealant into a tube or tire. Typically you'll take the valve off, and use an injector to put the slime into the tire. For tubeless tire setups, removing the valve core allows a higher volume of air to quickly get into the tire when you are first blowing it onto the rim. Some types ...


10

I always save the core out of blown tubes and have never had them not compatible. At the bike store you just see one jar. Might someone come out with non-standard - it could happen.


8

Can I calculate (approximately) how much air pressure is lost by measuring the hose length and diameter? No, you cannot tell how much pressure is lost based on the size of the hose. This is not because there is not enough information to tell but because the hose is irrelevant. You seem to be under the impression that there is some total amount of pressure ...


7

With MTB tires, there's really no issue in drilling out the valve hole to a larger size since the rims are so wide to begin with. You can do it yourself with a drill bit (3/8" or 10mm) or have your LBS do it. Sanding or reaming the hole afterwards is important, as well as making sure there aren't any sharp metal bits floating around afterwards that might ...


7

In my experience there is always some air loss when you remove the pump from a Presta valve, but that air is lost from the pump side of the valve. It's easier to see with a floor pump, since there's the hose to hold air. In a floor pump there's a check valve is at the pump end of that hose, and that will hold the air in the hose at high pressure even after ...


7

Short answer, it's not common at all and probably wasn't like that when the bike was new. The valve that you need is determined by the rim rather than the bike. If the rim is drilled out with a big enough hole for a schrader valve, then that's what you should use. If a schrader valve doesn't fit through the valve hole, then you should use a tube with ...


7

The valve is broken. You need a new inner tube. A new tube will cost $5 to $10, and most bike shops will charge $5 or so to change it for you. It's something you need to be able to do anyway. They'll probably show you if you ask.


6

For shorter stem presta valves in deep rims the trick to fill air is to first deflate the tyre about 50%, then push the pump head onto the stem with one hand while at the same time pushing the stem through the rim from the tyre side with your other hand. Then use the lever to get a good seal. When you pump it up, the increase in pressure in the head of the ...


6

I suspect a big part of the reason people leave them off is because it's something 'real cyclists' do- along with leaving off the dustcap, lining tyre logos up with valves etc. IME there are no real disadvantages to having them on apart from maybe a few seconds in changing tubes, which might get you some tutting on a group ride if people are hanging around ...


6

Have a close look. On a presta valve there is a wide threaded part that the lock ring attaches to. And a narrower part with the valve lock nut above it that the cap threads onto. If the narrow part has two flat sides to get a tool onto, then it's removable.


6

It is a commonly used quick and dirty fix when you don't have a purpose-built grommet to install in a rim cut for a Schrader valve. It may also not be a terrible idea if, for whatever reason, your Presta-hole rim has a burr or sharp edge and you want to avoid any possibility of problems with that.


6

It happens, especially if you remove the pump head not perfectly vertically or you move the pump head while pumping. You can avoid this by using a bit of hose on the mini pump like on this mini pump or bracing the head of the pump while pumping. Its not the end of the world if the valve core is bent -- I've run tubes for years with slightly bent valve ...


6

As noted in this old question there exist Presta tubes from which the valve core can be removed; in this case it might be possible to replace the valve core. However, yours appears to be a single piece valve (non-removable core). Since the valve is otherwise trash, I would try gently bending it straight using a pair of pliers. If it breaks, or doesn't ...


6

This is a Dunlop valve, also known as Woods. These valves always let air in but not out. The nut holds the valve in place, and you are supposed to unscrew it only if you want to deflate the tube. There are adapters from Dunlop to Schrader, but the most common way to inflate these is a simple hand pump that has just a rubber gasket instead of chuck like ...


5

The main reason I don't use them is that they rattle when they come loose. If you're heavy handed when pumping though, the nut is useful. Just remembered one other reason to use them... removing them if you've got a tubeless setup is a recipe for disaster


5

I've never had this problem. It would take considerable force to bend the stem. First be sure you have the nut on the Presta stem, and that it is screwed down firmly against the rim (though it shouldn't be wrenched tight). This will keep the stem from wobbling around in the rim hole, and makes the whole job easier. Then make sure that the wheel is ...


5

I wouldn't worry about it. Repeatedly bending the core could cause it to break, but as a one-off, it should be fine. I quite often end up with slightly bent cores, and don't normally bother bending them back, and I don't recall ever having a valve fail.


5

A tube is a sealed system. If the rubber isn't punctured and the valve is closed, there isn't anywhere that air could have gone all at once like that. The only thing I can think of is maybe you do have a small blowout tire side, and somehow the tube is sitting flush against the tire in such a way that it's holding it closed for now. May be worth taking ...


5

The cheapest solution is to try and remove the burrs or sharp edges that are cutting the tube. This can be done with a small file or a piece of emery cloth cut into a small strip and pushed through the hole. If the rim is double walled it will be difficult to get at the inner edges. The alternative is to purchase a set of schrader to presta adapter sleeves. ...


4

Make sure you unscrew the presta valve first. There is a small top piece that must be unscrewed before you place the pump onto the valve. If all is correct, you should be able to press onto the presta valve and air will be released. Once your presta valve is open, place the pump nozzle over the valve with the locking tab DOWN. Press firmly (you might hear ...


4

First you need to make sure you have the right chuck setup. If the pump you have is the one in the link then it claims to be auto-converting between Schrader and Presta -- you can skip to the next paragraph. But if you have a slightly different pump it may require manual conversion. As you press the chuck onto the valve you should feel some resistance as ...


4

In case someone still reads this, in addition to protecting the valve, you can cut the plastic top off with a knife or razor blade at a gas station and you have an instant Schrader adapter!


4

What you need is a valve core (provided the stem is threaded to take a removable valve core) [The question is, what happened to the original one?] The cheapest option and easiest option is to just buy a new tube.


4

You don't actually have to decide :-) For bicycles you want a pump that is capable of pretty high pressures (at least relative to a car) and most bicycle pumps can do either Presta or Schrader valves. Many floor pumps have a reversible head (two heads in one). For frame pumps it is common for the pump head to be convertible between Presta and Schrader. ...


4

The problem is your pump's valve chuck. Some valve chucks press the valve's center pin, which lets the pressure from tire to pump and allows reading the pressure. Some other chucks, such as the one you have, do not do that feature. If pressure drops to near zero after every stroke, there may also a leak somewhere in your pump. Replacement valve chucks are ...


4

Perhaps its obvious, but maybe the tube has a leak? Is it an old tube that has perished and is just letting air out as fast as you pump it in? Perhaps try taking the tube off the wheel, put it in a bucket/tub of water, and then pump. Can you see bubbles somewhere?


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