6 Physical Forces that Affect Bicycling

Bicycle Wheel Spokes SprocketAlbert Einstein made the statement that “Life is like riding a bicycle—to keep your balance, you must keep moving.”  While the comparative facility of riding a moving bicycle is obvious to everyone who has tried to sit astride one in a fixed position, the advantages of keeping busy generally are less clear.  However, they become more easily discernible in the wake of an injurious accident, when there are deadlines to meet, agents to contact, and bills to pay.  Often, a person’s success in obtaining compensation will depend on their ability to stay on top of things, even while dealing with an injury.  As with a bicycle ride, keeping astride of things requires a constant push toward progress.

However, it is far preferable to avoid bicycle accidents and thus steer clear of the process altogether.  This is easier when you know how bicycles work and how to take care of them.  Ergo, here for your enlightenment is a list of the forces which, combined with the efforts of the bicyclist, affect the way bicycles run:

1. Drag

Also called “air resistance” or “fluid resistance,” aerodynamic drag is a combination of the force acting in opposition to a bicycle’s velocity when it displaces the air in front of it in its progress and the friction of air against the bicycle and its rider.  There are, in addition to aerodynamic drag, two other forces that work directly against the forward-moving forces propelling a bicycle:  mechanical drag and tire drag. Mechanical drag is generated by friction in the bearings and chain.  Tire drag is “the energy that is lost when the tire is rolling[;] and the main reason for loss of energy is the constant deformation of the tire.”

Since drag reduces a bicycle’s speed, it is common for bicyclists to look for ways to reduce its effects.  Tire drag, for instance, decreases with an increase in tire pressure.  However, highly-inflated tires are highly susceptible to jolts when the bicycle encounters bumps and ruts in the road.  The less control the rider has over their ride, the more prone they will be to bicycle accidents.  Therefore, the best tire is firm enough to facilitate speed, yet soft enough to absorb the bounces.

2. Friction

In addition to the natural tire drag caused by the compression and recovery of the tire’s shape, friction also comes in other forms—for instance, contact with outside surfaces, such as the road.  While friction does not vary with speed as much as drag does, it varies quite noticeably with surface material.

As most people know, friction is generally at its most fricative on rough ground and less apparent on smooth terrain.  On the other hand, the loose stones, gravel, etc. that are often found on rough ground can be as treacherous as a smooth sheet of ice.  Thus, departments of transportation and proprietors of roadways have a responsibility to keep them as safe as possible for the traffic they will support.

3. Angular Momentum

Angular momentum—the power that drives bicycle wheels forward—is one of the forces that allows bicycles in motion to remain upright.  This is because the Principle of Conservation of Angular Momentum dictates that, barring the action of some strong external torque, the angular momentum will remain constant.  Or, in layman’s terms, “a spinning bicycle wheel resists efforts to tilt it and point the axle in a new direction.”

While a strong gust of wind or a conquering schnauzer probably aren’t enough to knock over a bicycle in motion, other traffic hazards like inattentive drivers are more than a match for angular momentum.  To reduce this risk, bicycle lights, reflectors, and visible clothing make it easier for motorists to spot the smaller traveler.

4. Centrifugal Force

Centrifugal force also plays a role in the bicyclist’s ability to balance.  It can be defined as the tendency of an object moving in a curve to move outward from the center of that curve.  (You have probably seen this in action when a sharp left turn in an automobile has left you flattened against the right-hand side of the vehicle.)  Centrifugal force manifests itself whenever a bicycle turns:  the rider attempting to change direction, swerve, or self-correct is creating a curve with the wheel; and the centrifugal force created by this curving motion drives the handlebars upright.

However, a turn that has been improperly executed in haste (perhaps to avoid a bicycle accident) is less likely to end in the previous upright position than in a bramble bush off the shoulder.  Therefore, perpetual surveillance of the road is crucial to the security of the bicyclist.

5. Precession

The precession that is at work when a bicycle is moving can be defined as the way “the axis of a spinning object…‘wobbles’ when a torque [circular force] is applied to it.”  That is, the motion of a disembodied bicycle wheel on an axis is like that of a spinning top, moving in a circle, tilted toward the center.  However, the forces of the wheel’s forward rotation on a bicycle balance out the force that would normally cause the wheel to tilt sideways, allowing the rider to travel in a straight line.

While the gyroscopic forces at work are effectively neutralized by the bicycle’s design, improperly attached wheels may wobble precariously on their axis like a metaphor of an unsteady gyroscope.  When a wheel is out of true, and control is compromised, the risk of a bicycle accident increases dramatically.  Securely affixed wheels are a must in ensuring the safe operation of a bicycle.

6. Gravity

Underlying much of what makes a bicycle work is the force known as gravity.  Without gravity, friction, gyroscopic force, and, therefore, bicycling in general would be impossible.  However, another kind of gravity often accompanies the physical sort:  that is, the gravity of injuries sustained when the force of gravity exerts its authority in a bicycle accident.

When you or someone close to you runs afoul of gravity or any other force in spite of reasonable caution and adherence to the laws governing them, getting back up on the hobby horse can be a trying chore.  Luckily, there is help available for those who are trying to regain their balance:  Advocate of Utah Bicycle laws, personal injury lawyers at Christensen & Hymas specialize in representing those who have sustained injuries while riding a bicycle.  Whether or not you chose to retain their services, Christensen & Hymas offer free initial consultations and booklets for those wanting to learn what their options are.  To contact their office, call (801) 506-0800; or, to request a free booklet, call 1-800-LAW-BOOK or submit your request at UtahAccidentBooks.com.

Image courtesy of Alan Levine

 

Russ Hymas
Managing Partner at Christensen & Hymas
Russ Hymas is the managing partner at Christensen & Hymas. He promotes awareness of legal issues and drives positive change in the cycling community.

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