Bicycle Balance. The stability of the bicycle circulating in a curve is mainly due to the centrifugal force that acts on the center of gravity of the combination of machine and cyclist, and to the gyroscopic effect of the front and rear wheels.
When driving in a straight line, the action of the gyroscopic effect is also combined with that of the centrifugal force, because although it may seem surprising at first, the trajectory described by the machine is not completely straight, but rather forms a sinuous neo relative to the forward direction of the vehicle.
Thus, when driving “in a straight line” we actually describe small curves, alternately to the right and to the left. The reasons for this fact are explained below.
Summary
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- 1 Centrifugal forces
- 2 Center of gravity
- 3 Circulation of the bicycle
- 4 Sources
centrifugal forces
Centrifugal forces appear in all bodies that move along a circular path, and it is greater the greater the mass and speed of said body, and the smaller the radius of the path described by it.
Thus, for example, if we make a bolus suspended from a thread rotate, then the centrifugal force, its own weight and the tension supported by the thread act on it; Under the action of these three forces, the thread tends to position itself so that its tension is oriented in the same direction (but in the opposite direction) as the resultant of the centrifugal force and the weight.
Similarly, a cyclist riding a curve should lean inward enough so that the resultant of weight and centrifugal force passes through the vehicle’s fulcrum.
Gravity center
If his center of gravity is instead lower than it should be, the cyclist will fall, unless the centrifugal force acting on him is increased sharply; being the speed constant, this is achieved by reducing the radius of the described curve, that is, by properly turning the front wheel.
This action is favored by the gyroscopic effect of the vehicle’s wheels, because when they are forced to describe a circular path, they tend to tip out of the curve, thus exerting on the bicycle a moment that, like that of the centrifugal force , also tend or straighten it.
This gyroscopic moment acts constantly on one wheel as well as the other, so that the rider can actually lean into the curve. In the event that the cyclist is in danger of tipping over, he can therefore straighten the vehicle by turning the front wheel more to increase the centrifugal force and the gyroscopic moment; Said wheel, rotating in the steering tube, already indicates to him in a certain way “by itself” the direction in which he has to turn.
Thus, for example, if the bicycle —and with it the front wheel— tends to tip over to the left, the wheel also deviates in case it goes to the left, due to the gyroscopic effect and thus begins to describe a more closed curve; consequently, the centrifugal force and the gyroscopic moment are increased, and these in turn prevent the vehicle from overturning.
The effects just described can be greatly enhanced by proper construction of the steerer tube and wheel fork .
When driving without hands, e! gyroscopic moment that appears in the front wheel when the bicycle is overturned is enough, traveling at a sufficient speed , to turn the steering tube in the precise direction and angle so that the resultant of the weight, centrifugal force and gyroscopic force passes through the support point of the vehicle, and thus prevents the latter from overturning .
Circulation of the bicycle
When riding in a straight line, the bike first makes, for example, a smooth curve to the right; then it straightens up, due to the centrifugal force and gyroscopic effect acting on it; then it inclines to the left, and describes a gentle curve to this side; it straightens again by the action of the centrifugal force and the gyroscopic effect; it then deviates to the right again , and so on, so that you actually have a sinuous path .
