Answer
A sphere or a cylinder on a level surface will be in neutral equilibrium.
When the object is moved on the level surface, there would be no change in gravitational potential energy and hence no gravitational work is done. Hence, the sphere or a cylinder must be on neutral equilibrium.
Work Step by Step
Basically "popping a wheelie" is done by changing the center of mass to the rear wheel. When a bike is running, it is in equilibrium as the normal force that earth applies on wheels are balanced by gravity. During a wheelie this equilibrium is disturbed by unbalancing the torques of the wheels. We can do this by decreasing the load taken by front wheel until it is zero.