Here is a summary of the math. You may want to go to the link
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Cycling at a speed of 10 miles per hour (very close to the overall average biking speed for pedestrians) for 6 minutes, a 170-pound person burns about 51 calories, while a 198-pound person burns 59 calories. Of course, changes in pace also result in a change in the amount of time spent on the bike per mile, as well as changes in how many calories you burn". https://www.livestrong.com/article/1...king-one-mile/
When you reduce your calorie consumption by eating less and/or burning more by 3600 calories, you will lose one pound. You can investigate the calorie consumption you are consuming now to maintain your weight by using an online calculator. You are likely consuming somewhere around 2300 calories give or take 10%. Consume 'X' less calories and burn X more calories by exercising more, will provide the answer to your original question in terms of timing your weight loss. From my understanding, everytime you reach that 3600 calorie reduction, a pound goes away. As you do the math, the closer you get to your target, your calorie requirements go down as well, so it takes less food and/or more exercise or/or more time to reach the 3600 calorie reduction goal.