Our public pools aren't in the best condition generally but not sure if there is one by luck in Rosebank. However you can do a club visit to the local Virgin Active gym http://www.virginactive.co.za/clubs/rosebank

I'd look at Virgin Active - they used to do day passes or short term free trials. I'd stay away from renting a bike unless you are able to ride with a local group - Cycle Lab used to rent but that was a long time ago. Cycling focused (as opposed to fitness focused) spin classes used to be pretty common both though Virgin and some of the bike shops

the pool I use when in Jhb is the Linden pool, 25m. It's heated but not warm ;-)
Couldn't find an official web page for it, but this gives most of the info,


https://www.jozikids.co.za/...ublic-swimming-pool/

Not too far from Rosebank, but depending of time of day, could be a long (time) drive.
The gym pools like Virgin might work too but I haven't tried them, have a sentimental attachment to the Linden pool, used to ride my bike there at 5:30am summer for pre-school workouts..

I don't know anyone who rides in Jhb, the traffic is bad, the drivers worse, and the roads appalling.. mostly they ride trainers, or get together on Sunday mornings to drive out of town to quieter roads.

There are some MTB parks nearby which would be the best bet for a ride, they usually have rentals. It's a very packaged experience though..
http://bikepark.co.za/