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54 votes

Why do we need air-filled tires?

Is this a conspiracy of bike and wheel manufacturers, to maintain a steady demand for tubes and tires? No, because if it worked as well as you suspect, someone would have made it happen and taken all ...
whatsisname's user avatar
  • 12.2k
32 votes
Accepted

How does a bicycle pump *head* work?

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 ...
L.Dutch's user avatar
  • 7,151
30 votes

Why do we need air-filled tires?

There are two good answers here already, I'll add the relevant physics. Any suspension has three key variables: Its spring constant, i.e. how quickly the force rises as the suspension is compressed. ...
cmaster - reinstate monica's user avatar
16 votes
Accepted

What's the specific use in carrying a pump?

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 ...
Nikolai's user avatar
  • 418
16 votes
Accepted

Using a schrader pump on a presta valve

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 ...
gman's user avatar
  • 390
16 votes

Will this electric air pump suit my tires and work for me?

In my experience, batteries are frequently flat when you need them. This unit has the likelyhood of sitting unused for months, going flat, and then being useless when you really need it. I strongly ...
Criggie's user avatar
  • 126k
15 votes

What is the difference between hand pumps for road bikes and mountain bikes?

Pumps for road bikes are designed for low volume and high pressure and pumps for MTBs the other way round. If you try to use road bike pump with MTB, it will take much longer than necessary and if you ...
ojs's user avatar
  • 22.2k
13 votes
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Floor pump blowing wet air?

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 ...
RoboKaren's user avatar
  • 29.2k
13 votes

How to disassemble a Topeak JoeBlow Sport II

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 ...
Sylvain G's user avatar
  • 251
13 votes
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How does this hand pump work

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 ...
pseyfert's user avatar
  • 1,023
12 votes
Accepted

How do tire pumps work?

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 ...
bobflux's user avatar
  • 1,784
12 votes

Why do we need air-filled tires?

We don't, and alternatives exist What we need is some level of compliance in the tyre. Rolling resistance at this level is governed by the tyre's ability to roll over small surface deviations. Air (...
Graham's user avatar
  • 1,099
10 votes
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How does a double-headed bicycle pump work

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 ...
Max Power's user avatar
  • 547
10 votes

Inflating My Bike Tyres

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 ...
Chris H's user avatar
  • 60k
10 votes
Accepted

What is the typical structure and location of a check valve in a floor pump?

I managed to fix it! The only valve like thing I could find in the pump was a small bit of brass tubing, but it was hollow all the way through so figured there must a small ball that is displaced when ...
plodsmeade's user avatar
10 votes

The pump needle broke off, leaving the base in the nozzle. How to remove the stuck base?

I just had this same thing happen last week. I straightened out a paper clip and bent a small hook in the end. Put the hook through the small hole in the center of the needle base and pull up. It came ...
Noah Sutherland's user avatar
9 votes

"Soft" valve insert for easier pumping

With the car (Schrader) valve it also happens to me that I cannot start pumping. Usually when there is still some pressure in the tube. I am only creating a very high pressure region between the valve ...
Vladimir F Героям слава's user avatar
9 votes

What is the difference between hand pumps for road bikes and mountain bikes?

I'd say in this case that a road bike pump is the optimal general purpose pump for all bikes, except maybe fatbikes because the pressure gauge isn't optimized for accurately reading low pressures. It ...
juhist's user avatar
  • 19.5k
8 votes

What's the specific use in carrying a pump?

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 ...
Batman's user avatar
  • 46.2k
8 votes
Accepted

What valves are these?

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 ...
ojs's user avatar
  • 22.2k
8 votes

What makes a good floor pump?

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 ...
Max's user avatar
  • 1,711
8 votes

"Soft" valve insert for easier pumping

Cyclists today know the automotive style to which you refer as the Schrader valve. The valve with a rubber sleeve that you mention is called a Dunlop valve, also known as Woods. Within Dunlop valves ...
Nathan Knutson's user avatar
8 votes
Accepted

Considering modern bicycle trends (2021), why are presta valves still the dominant design?

I think you are correct; there is no technical advantage of Presta. But many things are not used for technical reasons but rather for momentum reasons. Personally I prefer schrader for all my bikes, ...
BetterSense's user avatar
  • 3,446
8 votes

Considering modern bicycle trends (2021), why are presta valves still the dominant design?

Presta (btw: we call it Sclaverand or simply road bike valve here in Austria) has one advantage: You can easily release air. There could also be some small weight savings and aerodynamic benefits. I ...
Michael's user avatar
  • 28k
8 votes

Roadside repair: how to use a screw-on Presta pump on a tube with a removable valve core

I once saw someone riding out of a bike park with their minipump wedged in the front wheel and tied to the hub between the spoke planes with a clean poop-bag. They'd had exactly this problem where the ...
Criggie's user avatar
  • 126k
7 votes

How do I know when it's time to pump up my tires?

The correct tire pressure for you is typically not whats written on the tire sidewall. That's an arbitrary number determined by the marketing and legal departments at the tire manufacturer, not the ...
Batman's user avatar
  • 46.2k
7 votes

Is there a pump / Schrader valve adapter that prevent leakage during disconnection?

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 ...
Chris H's user avatar
  • 60k
7 votes

What makes a good floor pump?

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 ...
Chris H's user avatar
  • 60k
7 votes
Accepted

What size are the replacement o rings in the prestacycle set?

Got mine from AliExpress 10X5X2.5mm O seal ring for US$2. Tested it and it fix perfect.
Ron Chan's user avatar
7 votes

Pump head suitable for for small tires

It sounds like the issue that you're having is very similar to the one that time-triallists and triathletes have with disc wheels. Luckily they've come up with a solution for exactly that. What you're ...
Carbon side up's user avatar

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