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18

Those valve stems are too short for those deep deep rims you've got on there. You can tell just from the photos that the valve stem isn't sticking out far enough from the rim for the pump to fit all the way on it. Hence, it's not contacting the valve enough for you to inflate your tires.


14

In case you really want to drill, the only thing you need is a 10mm drill bit, and a sandpaper to give a smooth finish. It is true that the rim gets weaker, and very narrow rims should not be drilled, but I have performed this enlargement a couple of times and rode the wheels some honest hundreds of km in every kind of terrain, with no problem. I did this ...


13

Drilling out your rims will reduce the strength of the rim and increase the likelihood of cutting the valve stem on your tube. For a few dollars you can buy two of these: This adapter threads onto a Presta valve and effectively turns it into a Schrader valve. Presta valve tubes are the same price and are as widely available as Schrader valve tubes, so you ...


13

What I find helps, is: tap the valve post a bit to let out a small blast of air (after loosening the captive nut all the way, of course). That helps unstick things and lowers the pressure inside a bit to make it easier to start pumping air in. Just takes a quick tap. If you don't do that, you may need to pump slightly past the pressure of the tire to ...


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

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 ...


10

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 ...


9

I have had such experiences even at much lower pressures, (I ride diverse disciplines of mountain bike, so I use my tires around 40 PSI, but still...). I have found three main causes for inflation difficulty: I will discard air leaks as this one is pretty obvoius. 1) Faulty valve: Some valves get somewow obstructed, and won't get air in as easily as it ...


9

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 ...


8

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 ...


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

I do this all the time, basically use the presta nut on the inner side to avoid the tube getting "pinched" in the extra space, then if you can find another presta nut, screw that one to the outside where it's supposed to be. Works like a charm.


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 ...


6

I think the valve should be as short as possible while still allowing comfortable inflation of the tire. On the other hand, a longer valve usually "won't hurt", specially if you have more than one bike or your group of fellows use to lend spare tubes to one another during rides (happens a lot to me, but in shcraeder-equiped mountainbikes). Hope this helps!


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

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 swapped out both tubes on my mountain bike with Presta (less chance of crap getting in to the valve and it means I can carry the same CO2 inflator as I do on my road bike) and got the bushings - once they were in I've had zero issues with the valve stem. I'd definitely recommend putting one in since there's the chance that the valve stem could rub against ...


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 ...


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

"Remove valve cap, unscrew thingy in valve, and tap it a little - a jet of air shoots out. OK." You've got that right. If you have the proper pump, and the chuck is working properly, then simply pushing the chuck on and flipping the lever should do it. Normally, when you press the chuck on far enough a little button in the middle of the chuck will press ...


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