To lose weight and keep it off: You will need a high amount of physical activity unless you also adjust your diet and reduce the amount of calories you're eating and drinking. Getting to and staying at a healthy weight requires both regular physical activity and a healthy eating plan. The CDC has some great tools and information about nutrition, physical activity and weight loss. For more information, visit Healthy Weight. Reduce Your Risk of Cardiovascular Disease
If 10 revolutions per minute equal 1 mile per hour, then 1 rpm = 0.1mph. At 25rpm you should br producing 2.5mph, and at 35rpm you should get 3.5mph. I would suggest you measure the length or distance you are actually achieving, and see if this stacks up.
We assume you are converting between mile/hour and knot. You can view more details on each measurement unit: mph or knots. The SI derived unit for speed is the meter/second. 1 meter/second is equal to 2.23693629205 mph, or 1.94384449244 knots. Note that rounding errors may occur, so always check the results. Use this page to learn how to convert between miles/hour and knots.