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35

CO2 charger cartridges are used for bike tire inflation because they are a common, inexpensive product that has been around since the 1950s. Their other uses include powering air guns and inflating life vests. They were originally developed by the Crosman Corporation and marketed under the name "Powerlet". Powerlet cartridges are filled with CO2 presumably ...


26

I believe you will find these articles informative: The hidden life of a CO2 cartridge [PDF] The CO2 Cartridge … an Under-Appreciated Marvel of Technology! — George Fox Lang [PDF] At room temperature (below the 31°C/87.8°F critical temperature) a CO2 bottle is to a practical extent self-regulating. This is not possible with simple compressed air. You ...


17

The increased weight of the larger wheel (if indeed it does increase) will of course add weight to the bike, but additional weight adds very little rolling resistance (though it does of course affect hill climbing). It is a myth that "rotating mass slows you down". In terms of top speed there's no difference between weight on the wheel rim and weight ...


17

Get an inclinometer. They're not particularly accurate, but readout is instant and the price is right.


14

The three-foot extension noodle is absolutely obnoxious and a genuine safety hazard (for starters, how is another cyclist supposed to safely pass her?). The original point of these noodles, as I've seen them, is to cut one as wide as the widest part of your bike so cars could better gauge how much distance they needed to pass you. Perspective distortion and ...


12

Assuming you want the center of gravity of the bike alone (not with a rider), there is a very simple procedure you can perform yourself, as long as you have some bike (you could borrow one): For simplicity, strap the front wheel to the down tube of the bike, so the handlebars won't turn; You could also strap the brake levers in the "full braking" position; ...


11

Most of the Garmin Edge series GPS cycling computers can display grade. The Edge 500 and Edge 800 (not the Edge 200) have barometric altimeters to determine altitude. You can then change or add a display data field to show the current grade. Funny you ask as I just put added the grade as a display field this morning on a hilly ride. It updates the grade ...


11

You can do it, because your bike is connected to the ground. The work done when moving an object is proportional to distance and resistance force (which consists of air resistance and rolling resistance for bikes). The air resistance depends on air speed (ground speed + wind speed), but distance depends only on ground speed. Going slower reduces the energy ...


9

Your opening claim: Everyone knows (citation needed) that (at fixed rim diameter) tyres with smaller section require less effort to move around (at least on a paved road). Is actually not true. Your next claim isn't true either. The contact patch area for a tire will be nearly the same regardless of what width tire is used, for a given pressure. If I ...


9

After reading the answers here and becoming more curious, I found this article, which agrees with @Daniel. to briefly summarize it, they found that at the same tire pressure the narrower tires deflected more and had a lower stiffness (force over displacement) A curious finding is that a difference of 1 bar (14psi) makes more of a difference that a 5mm tire ...


8

You can do this because of the gearing of the bike. When you're riding at a slower ground speed, if you shift to a lower gear to keep your pedal RPM the same, then the same force on the pedals produces a higher thrust at the tire. Even if you do not shift, it is easier to produce higher force on the pedals at lower RPM. The strength of a cyclist is ...


8

Yes, there has been tons of in depth analysis on this, and the equations are rather simple so you can answer the questions for yourself given different scenarios using the Equations of motion for cyling Assuming you are on a road bike, on a flat road, with reasonable tires, the vast majority of energy is overcoming aerodynamic drag, about 70-80% After that,...


8

This explains part of the reason in what may be too much detail:http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch4/deviation5.html If you're going to read any of it, read the material starting after the table listing "van der Waals Constants for the Various Gases". It calculates that compressing CO2 from 1 Liters to 0.2 Liters using the Ideal Gas Law (...


6

Wheel size is a trade off. In some ways, you want the wheel as small as possible, in other ways you want the wheel as large as possible. There is no "right" size really, except that it's handy to have the same size as everyone else so standards have risen up. The benefit of a smaller wheel is they are cheaper (less materials to make them), they have less ...


6

You are going at constant speed when the driving force from gravity Fg is equal to the drag (air resistance) Fd plus friction (rolling resistance) Ff: Fg = Fd + Ff When coasting down a hill, the driving force is the component of the gravitational force parallel to the road: Fg = m g sin(a) Here, a is the slope (angle with the horizontal), m is the mass ...


6

The loss is friction in deformation of the rubber of the tire. When you flex the tire from round (when not on the ground) to flat (when touching the ground) there is heat generated. If the tire is narrower and the pressure is higher, there is less rubber involved in the flexing. It is true that higher pressure means less contact patch, but that is not ...


6

The answer to your title question is "moving air exerts a force on obstacles", and deep section front wheels have more area affected by side winds so there's more force. In any crosswind there will be some side force that applies a turning torque on the front wheel of almost any bike (viz, zero rake bikes have been made, but they have less trail than is ...


6

Yay! Another physics question. Restating the question: if the rider power input is constant, does the bicycle velocity change if the drive-train gear ratio is changed? Let's assume the road surface, wind speed, gravity etc. all remain constant. Bike and rider are on a surface with no gradient. Short answer is that constant power results in constant ...


6

There are, but measurements typically will be protocol-dependent (and vary slightly between different wind tunnels). For example: Here is a link to a comparison done at the A2 Wind Tunnel in North Carolina almost a decade ago, on bicycles standardized to frame and wheels, but without saddle or handlebars. Other protocols may include saddles, handlebars, ...


5

Your question really seems to boil down to: Is using such a noodle illegal? What are possible outcomes if a driver still passes me too close? My answers to this; We don't know. This is something that most likely will be dependent on the laws of your country. So I would suggest you to find out something about "allowed transport techniques on a bicycle" ...


5

The answer is simple but the explanation behind the answer may be instructive. The simple answer is: the x-axis label should be read as (m/s)^2, not m/s^2. The longer explanation is related to this bicycles.stackexchange answer. The power needed to ride at steady speed on a flat road under calm wind conditions is Watts = Crr * kg * g * v + 0.5 * rho * CdA ...


4

Another approach is roughly guestimate the CM, then tie 3 short cords to 3 points each roughly 120 degrees apart in a rough circle. Tie the other ends of the cords to a ring or whatever and hang so the bike is essentially on its side. Adjust the 3 cords on the ring -- looser or tighter -- until the bike hangs perfectly level. The central rope will then be ...


4

Others have already discussed GPS and GPS-enabled phones, altimetric barometers, and inclinometers. Bubble inclinometers (such as the Skymounti shown elsewhere among the answers) can be affected by acclerations so to get the best readings you should be stationary. dGPS (differential GPS) is used in surveying instruments to measure grades, but these are ...


4

Cell phones, usually not. Some applications will attempt to massage the data using elevation information provided from third-parties, but its a crapshoot at best. A dedicated GPS with a barometric altimeter is probably your best bet. I can't really speak to their level of accuracy, but it's certainly better than other practical options. If you just want ...


4

Drag increases with speed. Drag is both rolling resistance and wind resistance. A steeper slope is more gravitational pull. Terminal velocity is when the gravitational pull equals the drag. On a mild slope it will be only a few miles an hour. On a very steep slope it might be over 50 mph. A 7% slope is around 20 mph on road bike on a road.


4

The bicycle is a deceptively simple machine. The physics behind bicycles is actually quite complex, with multiple forces interacting to produce self-stabilizing behaviour (i.e., ghost ride a regular bike then run along and strike it, the bike will deviate from its current trajectory and self right). For a good rundown of the main physics principles behind ...


4

There may be other factors that affect "shift quality", if I understand what you meant correctly, but the most significant by far is “direction of force applied. Basically for a gear to change the mechanism just pushes the chain “off rail” enough in the direction of the new gear. When the chain has a higher tension applied on it the derailleur doesn’t have ...


4

A bicycle wheel is a complicated structure. Take a spoke in a wheel for example. The spoke is statically indeterminate because it's not mounted to the rim with some sort of bearing; instead it's mounted to the rim with a nipple, which can and does induce a bending moment in the spoke. The rim is similarly statically indeterminate because it's connected to ...


3

Partly it's due to the way that wind speed is measured. The standard for wind speed is to measure it 10 metres above ground level. Closer to the ground, an effect called the boundary effect kicks in and the wind speed is slower (in fact, the wind speed on the ground is effectively zero). According to this site, wind speed on a flat grassy plain can be ...


3

While it's true that a larger chainring will have slightly less friction and thus slightly more efficiently, it's an extremely negligible amount, that you wouldn't be able to feel. More importantly, are your crankarm lengths different on the new crankset than the old? That makes a much bigger difference. For example, if you've went from 175's to 170's, that ...


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