Bicycling uses different muscles than walking than swimming - or at least uses muscles in different ways.

For me, walking outdoors is 10x's more fun than on a treadmill - someplace where there is nature or a river or something similar.

While the exercise is GREAT, the only way to really lose weight is permanent diet changes. Exercise really uses very few calories, but it does build muscle strength, which will use a few more calories, and make one feel a lot better. I.e., for most folks a mile on a bike burns between 45-70 calores, depending. Therefore, one would have to ride about 70 miles to consume 3500 KCal to use up a pound from their body, and one would likely be so hungry as to consume about that much after the ride. So, diet changes must be combined with exercise.

There is an absolutely great and supportive sub-forum on this web site called the Clydesdale forum with lots and lots of folks in your situation, and ideas and suggestions about accomplishing your goal. At 201 lbs, I still qualify (200 lbs is the cutoff). Go there and ask for help - folks do it all the time. There are folks there who have lost 100's of lbs.