Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.

Hot answers tagged

32

What you have is basically a cylinder of rubber. When you lift the lever, the cylinder is compressed on the circular faces. This results in the sides expansion, which will "hug" the valve giving the sealing effect.


19

Note: this calculation makes many assumptions, so it's only useful in an 'average use case', not some sort of exact measurement. If you find better information, please post it and I'll update the answer. How many pumps you would need to fill up a tire depends on many variables. First, the volume of your inner tube, which can be approximated as a torus (...


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.


17

Yes, people riding with a frame pump or a mini frame pump will use this in conjunction with a repair-kit (spare tube, patch kit, tire levers). Most if not all recreational cyclists carry some method of a repair kit because flats happen and it doesn't have to mean the end of your ride. Generally with practice a reasonable time to fix a flat is 5 minutes. ...


16

If you're at home, use a floor pump. They are very easy to use and have a gauge so you can measure the pressure. When you're on the road, the quickest and easiest way to get you back on the road is to use CO2 cannisters. They are not that cheap though and the CO2 will leak out of the tube faster than air (mostly N2), requiring topping up over the next few ...


16

I figured it out. I needed to screw the adaptor on the presta tire valve, then attach the pump head. I was instead putting the adaptor in the head and then pushing it on the value but it needs to be screwed on first. I feel dumb but at least my tires are now inflated


14

It's a "dunlop" valve. Also called "woods". I used to see this years ago in BMX bikes. For best results we'd use to have a schrader adapter (google: dunlop to schrader adapter) so we could inflate with schrader pumps.


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

Yes, floor pumps can condense water in them. The water is from atmospheric water vapor. When the pump walls are colder than the surrounding air, the vapor can condense just like dew forms on leaves in the morning. Temperature swings assist in the formation of dew and this is made worse by leaving it on concrete, which is not only often much colder than the ...


13

From the disassembled photo, it looks like if you put the parts back together the pump will work for Dunlop valves and Presta/Sclaverand valves (roughly any narrow type valve). You should be able to put the rubber and the red thing the other way around in. Such that the narrow pointy thing of the red part points outwards and the rubber has a wider opening to ...


12

There are two main standards: Schrader and Presta. Schrader is the standard auto tire valve, while Presta is thinner and has a little knurled knob on top. Schader is relatively straight-forward to use while Presta requires a little finesse. Most newer "floor pump" valves are "agnostic" and will fit either style without conversion, but some require ...


12

What kind of valve do you have? If you have Presta valves then you need to unscrew that little knobbie thing on top until the knobbie is all the way unscrewed against the bump on the end of the shaft it rides on. With either Presta or Schrader you can have a problem with the pump if you do not press the pump chuck all the way onto the valve. Especially ...


11

Well... I tinkered carefully and was able to remove the top cap without breaking anything. 1) There are 2 small holes on the sides, right above the hose holder clip. You must push in the tab that keeps the top cap secure using a pointy tool and turn the cap slowly clockwise. Here you see it with the tabs disengaged and showing the holes the tabs click ...


11

Someone made a nice video. There is a rubber seal around the piston which makes it air-tight with the inside of the cylinder. Then there are two check valves which only let the air flow in one direction: one to allow outside air in when you pull (but not let is out when you push), and one to let the high pressure air inside ...


10

That is a Presta Valve. Your pump, I am going to guess, is a Schrader Valve. You can buy a Presta pump from a shop or buy a $2 adapter.


10

A small piston or diaphragm is centered by a light spring when pressure is equal and this allows a little air passage opening exposed on both sides. Any pressure imbalance causes the the mechanism to move slightly to one side which closes the low pressure passage and fully opens the passage on the high pressure side. In physics and engineering this is called ...


10

That pump is set up for another sort of valve (Presta, you have Schrader). You can probably switch it by unscrewing the end, removing the rubber part and putting it back in the other way round. You might need to turn round a plastic or metal part as well.


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

Don't bother with an air compressor. Get a proper bike pump. They are cheaper, and will fill a tire to 60 psi with minimal effort. A good bike pump will also require less maintenance. Also it'll only take a couple pumps to top up your tires. Much less time than to drag out a big air compressor. Have you had problems with standard floor/track pumps? What ...


9

The front one is Dunlop and the rear one is Presta. The rear rim is drilled for Schrader valve, which is thicker than Presta. I don't know the reason for this, but I suspect that whoever put the bike together just used the parts that were at hand without any planning.


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

Your valve has slipped partially inside the hole in the rim where it exits. Normally it's on average about 1-1/2" outside the hole. You'll need to inspect the valve body to see if it's cut. You can't put a pump on it because the main body of the valve is stuck. First fix the valve body position, then inspect... Here's how to fix: Deflate the tire about 90%. ...


8

Generally, most prepared cyclists carry a spare tube, some tire levers and a bit of money or something else that could be used as a tire boot. With these, if you have a damaged tire or tube, you can normally put in a new tube and continue your journey. For tubeless riders, a spare tube is sometimes necessary. A pump or CO2 cartridge is necessary to inflate ...


8

I'd say it must have a good sturdy build and should be stable. It must have a good pressure control and display; it should have a proper pressure range. It should have a good connector with detachable/replacable plugs. It should have a long hose, so you're not too close to the bike and make full control strokes on it.


7

The correct answer is yes and no. There are in fact two types of Presta valves: One where the core can be removed. Those are often used with tubular tyres so that the inner tube can be filled with a sealant (latex) fluid. Some higher quality tubes also have removable core valves for the same purpose. Normal and cheaper tubes have Presta valves where the core ...


7

You have a Mk2 Brompton which uses a slightly shorter pump. I think your pump might be a Mk2 also. Does it physically fit within the frame? (the handle goes towards the axle). The bit you are missing is the adapter bolt for holding the Zefal pump. This goes into the seatpost-end pump bracket and slots into the hole on the nozzle end of your pump. You could ...


7

Much of the drop you see will be due to the reconnection, not the disconnection. When you disconnect the pump you have 120psi in the tyre and the hose, gauge and a little bit of pump. This immediately drops to zero (as these are all gauge pressures). Most of the hissing you hear is this air leaving the system When you reconnect the 0 psi in the hose ...


7

A double-sided chuck for both Presta and Schrader valves, with sturdy lever "Universal" chucks don't work as well and aren't as durable (IME, so not the most expensive), while the type that involve switching bits inside are one thing for carrying on the bike when space/weight is at a premium but another for workshop use.


7

It's quite likely the head is dual type switchable. Unscrew the retaining cap. Remove the rubber thing. You might need some gentle encouragement with pliers. Spin it 180. If the other hole is Schrader sized, You're in luck. There will be a plastic widget under the rubber bit. This also needs to be flipped 180 to expose a pin. Put the head back together. ...


7

That sounds like a broken seal in the pump. I had to google the brand as I'd never heard of it before. There are a few amazon reviews that also state the pump didn't work on arrival. Link to Amazon Given that evidence, and the tragedy that is the Pumpico website: https://thepumpico.com/ I'd suggest returning the pump and buying something from an ...


Only top voted, non community-wiki answers of a minimum length are eligible