BB I bet you knew this would get me going.
I have been riding bikes most of my life from road bikes, mountain, downhill, and even BMX in the old farts class. I have just returned from a two week Downhill riding in Chiang Mai Thailand one of the best downhill places in the world and road with riders from all parts of the world. Going again in July.
Bike riding is a great way to get fit without to much impact on your body. It also will tighten up your ass and get it looking great.
If we are talking Road bikes and doing longer distance your ass will be saw the first few times as a road bike has not got a cumforable seat. You can get some bike pants and they have padding in them. You can also buy padded under ware. Most bigger bike shops sell them.
If you are not a fit person riding is a easy way to start. After a bad bike accident about 7 years ago it took me over a year to recover from some broken bones and with little excersise. I started road riding again and was finding it hard to even do 3 or 4 kms at first. Slowly worked it up over a few months to 20k a day.
I ride most days road, mountain or downhill but I still wont ware those puffy looking bike pants.