Please help docs! Is stairmaster, bike in a gym good ways to lose body fat?

These are two. Great forms of exercise to burn calories. When calories burned exceeds calories consumed then weight is lost. When weight is sensibly lost - fat loss often ensues. Mix up you cardio for great results. Engage in regular aerobic exercise (i.e. Running, swimming, nordic track, kickboxing, walking, cross country skiing, hiking, etc.).