I'm Bham born and raised. Oak Mountain State Park (XTerra championship race location) is the place to get in all three s/b/r at the same location, admission is $5 per adult. It's where most people in town do ows practice in a very nice fresh water lake, it has mountain and road bike options. If you're there on a Saturday and the weather is nice, expect to see lots of cyclists. It's 10-15 minutes south of downtown.

For pool swimming, there are lots of YMCA's that will honor a membership from another city. My Y's location just took the bubble off today, and they may be in the process of doing others this week or weekend, so best to call a particular location and see if their pool will be out of commission that day. All Y pools in Bham are 25 yards. Unfortunately there are no 50 meter pools in the are that are open to the public.