A cyclist is riding down a slope with an even inclination. If he is holding the brakes with exactly such a strength to cause the rear wheel to almost rise into air, then his speed while riding down the slope does not change. The center of mass of the system that consists of the cyclist and the bike is located exactly in the middle of two wheels, at a height h from the ground. The distance between the axes of the wheels is d. How big is the angle α between the slope and the horizontal direction? How big has to be the coefficient of friction μ between the wheel and the ground so that the cyclist could brake like it was described?