An endless rubber power transmission belt such as a CVT belt having a main belt body with a compression portion, tension portion, an adhesion portion, and a tensile cord in contact with the adhesion portion and embedded between the compression portion and the tension portion, angled sides, and a width to thickness ratio on the order of 2 to 3. At least one of the compression portion, the tension portion and the adhesion portion has an elastomer composition that includes a saturated ethylene-alpha-olefin elastomer, a staple fiber, and a pulp fiber, or an elastomer, a high-modulus staple fiber, and a high-modulus pulp fiber. The pulp fiber constitutes less than 40% of the total high-modulus fiber amount.