I had a shoulder replacement on the right and was in a sling for 3 full months. I started with "easy" things like swimming and even ended up getting my scuba certifications up through rescue diver in the first year post surgery. (I had to drag a 300lb man out of the water).

By that point riding a bike was no issue at all. Now at 10 years on (10 year shoulder-versary in October) there are still a few motions that will give me a little muscle twinge but nothing worrisome.