Catalyzes the oxidation of cyclopentanol to cyclopentanone and cyclohexanol to cyclohexanone. cyclopentanol + NAD(+) = cyclopentanone + H(+) + NADH cyclohexanol + NAD(+) = cyclohexanone + H(+) + NADH Alcohol metabolism; cyclopentanol degradation; 5-valerolactone from cyclopentanol: step 1/2. Belongs to the short-chain dehydrogenases/reductases (SDR) family.