55
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 ...
- 12k
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 ...
- 7,041
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.
...
17
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 ...
- 428
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 ...
- 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 ...
- 120k
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 ...
- 21.6k
13
votes
Accepted
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 ...
- 28.9k
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 ...
- 251
13
votes
Accepted
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 ...
- 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 ...
- 1,684
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 (...
- 1,049
10
votes
Accepted
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 ...
- 537
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 ...
- 55.7k
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 ...
- 141
9
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 ...
- 21.6k
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 ...
- 15.3k
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 ...
- 17.7k
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 ...
- 45.9k
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 ...
- 1,661
8
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 ...
- 1,865
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 ...
- 80k
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, ...
- 3,306
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 ...
- 25.8k
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 ...
- 120k
8
votes
Accepted
Pumps keep breaking
You say that you feel pressure in the side that's blocked when you cover it with your finger. In my experience these pumps that automatically switch where the pressure is being directed need a ...
- 4,921
7
votes
How to inflate a tire with a Presta valve?
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 ...
- 71
7
votes
Accepted
Brompton pump mount?
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 ...
- 186
7
votes
Accepted
Is my Schrader valve spoilt?
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 ...
- 534
7
votes
Accepted
Is it normal for a presta valve to unscrew into two pieces?
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 ...
- 8,251
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