We construct different almost Poisson brackets for nonholonomic systems than
those existing in the literature and study their reduction. Such brackets are
built by considering non-canonical two-forms on the cotangent bundle of
configuration space and then carrying out a projection onto the constraint
space that encodes the Lagrange-D'Alembert principle. We justify the need for
this type of brackets by working out the reduction of the celebrated Chaplygin
sphere rolling problem. Our construction provides a geometric explanation of
the Hamiltonization of the problem given by A. V. Borisov and I. S. Mamaev