Rims of wheels of many vehicles have seven spokes Since they cannot be equispaced do they not affect the balancing of the wheels at high rotational speed or is the error distributed uniformly?

Answer 1

Assuming all the spokes have the same mass and density distribution, I do not think there is any reason a 7 spoke wheel should be inherently inbalanced, as long as the angle between adjacent spokes is equal to 360/7 degrees. Similarly, a 3 spoke wheel would be balanced if the angle between adjacent spokes was 120 degrees. If you draw a line from one side of the wheel to the other that passes through the centre of the wheel and then calculate all the compenent forces parallel to that line, you will see they all balance out. Look up adding vectors and finding the component of a force if you want to do the maths. The doubt makes sense because 360/7 results in a fractional value unlike say 360/3 but one must remember that it is possible to analyze this fraction up to the required degree of accuracy. Also wheels anyway have to be balanced by adding weights after the manufacturing so as to correct errors in the manufacturing process so the same can be applied over here.