What is Bike: Definition and 191 Discussions

A bicycle, also called a bike or cycle, is a human-powered or motor-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A bicycle rider is called a cyclist, or bicyclist.
Bicycles were introduced in the 19th century in Europe, and by the early 21st century, more than 1 billion were in existence. These numbers far exceed the number of cars, both in total and ranked by the number of individual models produced. They are the principal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for use as children's toys, general fitness, military and police applications, courier services, bicycle racing, and bicycle stunts.
The basic shape and configuration of a typical upright or "safety bicycle", has changed little since the first chain-driven model was developed around 1885. However, many details have been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for many types of cycling.
The bicycle's invention has had an enormous effect on society, both in terms of culture and of advancing modern industrial methods. Several components that eventually played a key role in the development of the automobile were initially invented for use in the bicycle, including ball bearings, pneumatic tires, chain-driven sprockets and tension-spoked wheels.Although bike and cycle are used interchangeably to refer mostly to two types of two-wheelers the terms still vary across the world. In India for example a cycle refers only to a two-wheeler using pedal power whereas the term bike is used to describe a two-wheeler using internal combustion engine or electric motors as a source of motive power instead of motorcycle/motorbike.

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  1. F

    Why does a bike not fall over when it's in motion?

    Hello there, This is my first post on here, so I hope that I've posted in the appropriate sub-forum. My question might seem simple to some, but I haven't been able to find a satisfactory / understandable answer to this question. Thanks in advance for taking the time to respond.
  2. metapuff

    Why is it easier to balance on a moving bike than a stationary one?

    Why is it that it's much easier to balance on a moving bike than a stationary one? I've heard a few different answers: 1. The wheels of the bike each have their own angular momentum vectors, which like to stay pointed in the same direction, and hence resist tipping from side to side (sort of...
  3. G

    Solving For Rolling Friction in Bike Tires

    Homework Statement Two bicycle tires are set rolling with the same initial speed of 3.60m/s along a long, straight road, and the distance each travels before its speed is reduced by half is measured. One tire is inflated to a pressure of 40 psi and goes a distance of 18.0m ; the other is at...
  4. S

    Cycling power of a bike with engaging/disengaging flywheel

    Dear Friends I’m in need to solve a problem in physics, which might be easy for you but it is not for me as my background in physics is not good. I have a bike (drawn in simulation platform) with a flywheel connected to the crank (or shaft). The flywheel is not always fixed (or engaged)...
  5. A

    Bike Approaching Stopped Truck at Traffic Lights

    Homework Statement A truck is stopped at a traffic light. The moment the light turns green, it begins to accelerate constantly at 3.1m/s^2. A cyclist approaching the truck from behind with a constant velocity of 10m/s was 7.5m behind the truck when the lights turned green. 1)How much time...
  6. Feodalherren

    Constant acceleration, bike vs. car

    Homework Statement Vroom, vroom! As soon as a traffic light turns green, a car speeds up from rest to 50.0 mi/h with constant acceleration 9.00 mi/h + s. In the adjoining bike lane, a cyclist speeds up from rest to 20.0 mi/h with constant acceleration 13.0 mi/h + s. Each vehicle maintains...
  7. P

    What is the Direction of the Angular Momentum of a Bike Going Around a Circle?

    Homework Statement A bike is going clockwise around a circle of radius R (see below). The moment of inertia of each wheel around its center I_cm is NOT negligible. What is the direction of the total Angular Momentum of the bike about the center of the circle (point Q)? Consider when the bike...
  8. rogerk8

    Why is it possible to ride a bike?

    Hi! I simply wonder how it is possible to ride a bike. I do not understand why the pure forward motion cancels the mass-centre offset which I think always should be inherent in riding a bike. With mass-centre offset I mean that looking at the rider vertically it is impossible to keep...
  9. C

    Attempting to create a self rotating magnetic bike

    Hi all, new on here so thanks in advance for your responce's I am an avid cyclist and competant engineer, i dislike oil and gas so much i do not own a car. I cycle everywhere. I am tired of wanting to go long distances without assistance or a high top speed. I want to build a cycle with...
  10. R

    How fast you can drive your bike but not get wet?

    You are wondering how fast you can drive your bike but not get your feet wet when the road is full of water? The answer is simple: about 2.5m/s (meters per second) or roughly 9km/h (kilometers per hour), or 5.6mph. See below for the demonstation: This is a simple physics problem which is...
  11. S

    Why mileage drops if drive the bike beyond 60km/h?

    Hi; I am new in this forum. I was looking for such forum and at last reached to the right one. A question is in my mind, if we drive the bike within 60km/h range, we achieve a good mileage but beyond this limit, mileage drops drastically while we cover the distance in short time as compare...
  12. J

    Magnetic Resistance Exercise Bike Theory Question

    I am an electrical engineer disabled in a snow sking accident and am now a quadriplegic. I'd like to design an exercise arm bike and make it magnetically resisted because friction resisted is not conducive to minute changes in resistance. I have a magnetic resisted trainer for a road...
  13. J

    Statics, bike on inclined plane

    Homework Statement I´ll need an image to show the problem: A bike with length L is on an inclined plane, the distance between the center of gravity and center wheel centers A,B is L/2. Brakes are acting on the wheels so we have a static position. In the picture is possible to...
  14. S

    Deleting exhaust crap off my bike

    Long story short I am deleting the exhaust crap off my bike to do so I need to trick my ECU into thinking its still there. I need you guys to help me figure out what I need to do so... Please refer to paint shop drawing If you could talk me though it or draw me up something It would be much...
  15. K

    100kg Bike- torque needed to go up 10' slope

    Can some one please tell me the equation needed to caculate the torque needed 1. to overcome gravity trying to make you roll down hill and 2. ride up hill at 10km/h for a 100kg (bike & rider) on a bike with 66cm wheels on a 10' slope? cheers stan
  16. S

    Have a question about bike problem

    Homework Statement A bicycle is rolling down a circular portion of a path; this portion of the path has a radius of 7.78 m. As the drawing illustrates, the angular displacement of the bicycle is 0.877 rad. What is the angle (in radians) through which each bicycle wheel (radius = 0.330 m)...
  17. H

    Riding a Bike on an Incline Treadmill

    Hey, guys, my first time posting here but I need some educated individuals to definitively solve a problem from another forum. We are having a discussion about a bike on an incline treadmill (one presumably made for a bike). My contention is that it would still be relatively easy to pedal on...
  18. S

    Electricity generation - simple bike dynamo - can anyone explain this design?

    http://img404.imageshack.us/img404/9523/dynamos.jpg I understand that when the rotating magnet spins, current should be induced in the coils which powers the lights. So what is the point of the soft iron core? The rotating magnet should magnetise it because it is near it, and it should...
  19. L

    Fixing a Bent Bike Wheel: Is It Safe?

    I recently took a curb harder than I should've and my bike's rear tire now has a flat spot. Since my tools are currently all elsewhere I can't fix it myself. When I took it into the local bike shop the tech said that it was too badly bent to fix by simply adjusting the spokes (I agree with...
  20. E

    Downhill to uphill roller coaster velocities on a bike

    first off: hello, I'm new here. Homework Statement This is more of a personal quest than homework, a problem that I made into homework for myself. I set out to determine the equation(s) needed to determine speeds on a mountain bike at the bottom of dirt hills of varying grades and lengths...
  21. A

    Help needed for this question - Air pressure in a bike tire

    Help needed for this question -- Air pressure in a bike tire Homework Statement The Pressure gauge on a bike pump reads 8 bar at sea level on a day when the temperature is 21°C. Assume that the gas constant for air is 286.9 J/Kg K a) What is the density of the air in the tyre? b) What is the...
  22. J

    Calculating the Power Needed to Bike Up a Hill

    Homework Statement What power must a man of mass 85 kg have to bicycle 850m up a hill, inclined at 5.2° to the horizontal, at a constant speed of 15.6m/s? The force of friction on the man and the bicycle is 175N parallel to the incline.Homework Equations The Attempt at a Solution m= 85kg...
  23. H

    Automotive How can heat management be optimized in compressed air powered bikes?

    hey mechies, i know "compressed air powered bike" is one of the oldest concept of our engineers but still in their developing stage.. i am in my final year of mechanical engineering undergraduate course. And i am about to do final project by end of this year.. when searching for real time...
  24. M

    I want some advice on motorizing my bike.

    Hi! I thought of motorizing my 2 wheeler. 1) Now i want to know how much Voltage (DC motor) is required to turn my wheel. 2) The source of energy? (Maybe Electric). If electric, I know it will be difficult to use batteries to run the motor. Considering car batteries, they are just too...
  25. I

    Moment of Inertia of Bike Wheel

    Hi, I have conducted a few simple experiments involving a very ordinary, road going bike wheel. I came up with a value for the moment of inertia of 0.17kgm2 I really have no idea if I am in the right ballpark with that value, would anybody be able to enlighten me as to if that is a feasible...
  26. A

    Contactless dynamo for my road bike - help with the magnetics please

    Hi all, Would appreciate some help with the magnetics in a contactless dynamo I'm trying to build for my road bike to power some LED lights. I've got 8 rare-earth magnets mounted on the bike wheel, near the hub. They're flat, round magnets, around 2cm dia., mounted all the way around the...
  27. ArcanaNoir

    What do you think my bike is worth?

    I need to sell my bike to help pay for a new car. I'm trying to get an idea for what it's worth. It's a 2006 Ninja 650R with 12,500 miles on it. I laid it down once a few years ago, but I have sliders on it so the damage is minimal. The pictures are an accurate reflection of the damage. The full...
  28. H

    Moving bike stabilizes but standing bike falls

    A bike "B1" is on the go. Another one, "B2" is standing upright and still. Which one is more stable, in the sense that, if I push one, which one shall fall down more easily?
  29. Y

    Motor bike engines acting as a gyroscope keeping the bike upright

    Dear All This is a rather strange question for you one that i can find no conclusive argument to. when riding a large motorbike i am informed that the engine must be reved at low speeds in order to keep the engine spinning at a sufficient speed to enable it to generate a strong enough...
  30. P

    How Far North Did the Biker Travel in 10 Minutes with Given Velocity and Angle?

    Homework Statement riding his bike with v=(8.4m/s,25 degrees north of east) for ten minutes. how far to the north of the starting position did he end up? Homework Equations x=v^2sin2angle/g The Attempt at a Solution 70.56sin50/g theres not even a t in this.
  31. F

    How Far Can a Bicycle Lead a Car When Both Accelerate from a Stop?

    As soon as a traffic light turns green, a car speeds up from rest to 50.0 mi/h with constant acceleration 9.00 mi/h/s. In the adjoining bicycle lane, a cyclist speeds up from rest to 20.0 mi/h with constant acceleration 13.0 mi/h/s. Each vehicle maintains constant velocity after reaching its...
  32. QuarkCharmer

    Riding a Bike to Class: Students & Faculty Experiences

    Do any students here (or faculty for that matter) actually ride a bicycle to class? For the past few weeks I have been thinking it's a good idea. I live something like 2 miles from my university, and there are virtually no busy intersections that I would have to cross. Lately, traffic has...
  33. D

    Rotational Inertia: Front end of an airborn bike drops when brake is applied

    So every mountain biker or motocross rider knows to never grab the front brake in the air. When you do the front end drops and can potentially ruin your day in a hurry. I figure that due to the loss of rotational inertia gravity accelerates the front wheel more rapidly, but I would like to see...
  34. A

    Impact force on a bike off a 6 foot drop?

    Here is a question for the physics experts. Some people been debating about the impact force on a bike of a bike rider riding off a 6 foot drop to a flat landing. Mainly the debate is about if speed would lessen the impact force on the bike because of the impact angle. So, if a bike rider...
  35. G

    Bike Race Problem: Solving for Applied Force, Work, Power & Acceleration

    Homework Statement Contador climbs a 5 degree section of road for 8.2 km to the summit in 20 minutes 35 seconds. he is 62kg? his bike is 8kg and the resistance force is 21 N What is the applied force needed for contador to move at constant speed? what is the work done to reach the...
  36. G

    Hover bike - what is the minimum propeller rpm required?

    Hello, I read this article about someone who made a hover bike prototype from a motorbike and two propellers. Best part is, its classified as Ultralight and doesn't require a license to fly! I can totally see myself building something like that in my back garden! How can I calculate the...
  37. C

    Bike and Car both accelerate from rest ( intermediate problem)

    Bike and Car both accelerate from rest ("intermediate" problem) Homework Statement Basically, both a bike and car start from rest. The bike will not go any faster than (final velocity) 20 mi / hr. The car will not go faster than (final velocity) 50 mi / hr. However, at first, the bike is...
  38. B

    What is the formula for calculating the maximum deflection of a bike axle?

    My Question... To find the maximum deflection of this axle, can the formula: (W*a/24*E*I)*(3*l^2-4*a^2) Will the total length simply be 370mm(wheel to wheel), or will I have to include the total length of the axle?
  39. S

    Angular Velocity with Bike Tires

    Homework Statement Your bicycle tires have a radius of 0.33 m. It takes you 850 seconds to ride 14 times counterclockwise around a circular track of radius 73 m at a constant speed. (a) What is the angular velocity of the bicycle around the track? (b) What is the magnitude of the angular...
  40. M

    Work done on a stationary bike

    Our local YMCA is putting on an indoor triathlon and I am trying to come up with a formula to help them determine the winner of the cycle segment. The indoor triathlon consists of a 10 minute pool swim, a 20 minute cycle on an indoor, stationary bike, and a 20 minute run on the treadmill. The...
  41. F

    Question About Aero Bike Idea - Mike Flanagan UK

    Please, may I ask for a comment on my idea for the Aero Bike? I want to store energy in the frame of the bike, by pumping with your arms on the handlebars to create air pressure, (at the same time as you do your normal pedaling). Also perhaps regenerative braking can store energy too...
  42. Femme_physics

    How come you have more stability riding a bike than standing still with a bike?

    My friend asked me that this morning but I couldn't think of the answer. I know there's probably some major physical law behind it, but so many to choose from! Can you guys help me clarify this issue for myself and my friend?(when I say "riding a bike" - I mean riding on a bike. When I say...
  43. A

    Exploring the Physics Behind a Bike Helmet: Egg Survival Device Project

    well I am doing a project in my physics class where i have to create a device for an egg to survive a 11m fall. i created a device similar to that of a bike helmet. its been tested and it works but now i have to discuss the reason why it works. i need to include physics principles and the...
  44. U

    Conservation of energy of a bike uphill

    Homework Statement Jonathan is riding a bicycle and encounters a hill of height h. At the base of the hill, he is traveling at a speed vi. When he reaches the top of the hill, he is traveling at a speed vf. Jonathan and his bicycle together have a mass m. Ignore friction in the bicycle...
  45. D

    Flat vs inflated bike tire - friction

    Hey there I'm wondering why it's remarkably more exhausting to ride a bike with a flat tire, compared to a bike with a hard inflated tire. The friction force "killing my efforts" so to speak, should be the same; the normal force is the same (my mass doesn't change), and the friction...
  46. B

    Spinning Bike Wheel Direction: Answer 2

    1. Homework Statement {Number 5 on attachment. It has picture.} When a spinning bike wheel is placed hor- izontally, hung from a pivot at one end, the axis of rotation of the wheel will swing in a horizontal circle. In which direction does it turn (as viewed from above)? 1...
  47. B

    Solving a Spinning Bike Wheel Homework Problem

    Homework Statement {Number 5 on attachment. It has picture.} When a spinning bike wheel is placed hor- izontally, hung from a pivot at one end, the axis of rotation of the wheel will swing in a horizontal circle. In which direction does it turn (as viewed from above)? 1. downward...
  48. Evo

    4-Year-Old Can Be Sued, Judge Rules in Bike Case

    So, what kind of judgement could they get against a 4 year old? Can they get a judgement against future income? Put the careless kid in reform school? The article makes it sound like the judge feels the child intentionally or carelessly rammed her bike into the old woman, which may have...
  49. H

    Finding a Custom Sprocket for an Electric Motor Bike

    I have an electric motor that I want to use with a bike chain and not the small chain that is already on it. Using cad and getting a custom sprocket made might be the way to go, but finding a site that sells them would be more than likely be cheaper. I found that it is called a dual-d boreand is...
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