Forces on the wheel.
- In the radial direction (forces parallel to the plane of the wheel passing through the axis with their work line).
- in the tangential direction (forces parallel to the plane of the wheel that does not pass through the shaft with their work line).
- In the axial direction (forces which are perpendicular to the plane of the wheel)
In the radial direction, the wheel is loaded by the frame on the axle and by the ground on the tire.
In tangential direction the wheel is loaded at the hub by the driving forces of the sprocket wheel and the braking forces of the hub brake.
The driving forces and braking forces through the wheel to be transmitted to the road surface.
In the axial direction, the wheel at the axle loaded by the frame and at the tire by the ground. Normally, a wheel in this direction is only slightly loaded.
Because you can balance on a bike, the force will always be directed along the bike. The moment you go through a curve, you tilt to the left or right , to bring gravity and centrifugal force balance.
On vehicles with two wheels side by side, like cars and bicycle trailers, does the centripetal force in the axial direction on the wheel. The wheel is subjected to bending by this force. Also by wagging the bicycle wheel is subjected to bending.
Gravity remains downwards while the bike will be placed diagonally. The bicycle wheel must be sufficiently strong and rigid to withstand these forces, depending on the application, both in the radial, tangential and axial direction.
In the radial direction, the wheel does not have to be super stiff, since in this direction suspension is desired. In the axial direction, the wheel has to be stiff, in order to prevent the rim brake to touch the rim when it’s not used, or the tire comes against the fork. In tangential direction the spokes must be sufficiently strong to transmit the traction and braking forces to the wheel rim with tire.