What qualitative conclusions can you draw about the effects of bearing tightness and lubrication
condition on the rotation of the wheel? How does increasing the mass at the wheel rim alter the data you obtained? Are ball or roller bearings a 'better idea' than plane metal bearings for the wheels and the
pedals? Why? Is the rotational speed of the wheel time dependent? What are the interactions between the wheel and its surroundings that cause the time dependent rotational behavior? Can you estimate which of the effects you identify might be the most important?

Assume that the mass of the wheel and tire is located at the rim and that the additional mass due to the weights is at the radius of the weights on the spokes and evenly distributed circumferentially . Compute the moment of inertia of the wheel for the different weight locations you use. For these assumptions, the moment of inertia, I is given by: I = MR² + mr² where M is the mass of the wheel and tire and m is the total mass of the added weights. R and r are the radii at which these masses are located. 

Compute the rotational kinetic energy , T_rot, of the wheel for the various times at which you measured the wheels angular velocity. The rotational kinetic energy of the wheel when its angular velocity is w is:               T_rot = ½ Iw². Estimate the rate of energy loss by the wheel. Is this the same at all rotational speeds? Does it depend upon the magnitude of the wheel's moment of inertia?