Hey Painfully!
I am a Dr Gross bilat almost seven months out. I couldn't use the stationary bike until six weeks. But when I hit that date, believe me I did it (in street clothes in a hotel gym, just to see how it would feel. Felt great!) I didn't do much stationary biking, though, preferring to walk and swim outside.
I tried a spin class at about four months, thinking I needed the quad/glute work and hoping I would stick with it better than biking alone in front the TV. After attending a class, I asked Lee if I should be careful of anything and she told me to wait on spin class until six months out. I was disappointed. I did think I could appeal successfully, telling her I wasn't looking at SoulCycle and pretend Tour de France, but me on a bike in a dark room with loud music and other people. I would promise not to stand up on the bike. But I dropped it, deciding instead to swim more. (FWIW my bone density was great, but my femoral head on one side was pretty eaten up by cysts. I am also a woman with dysplasia in her early fifties. Maybe that is why she told me to wait? Or maybe she just thought I sounded too eager and reckless?!?!)
Four months to wait, huh. You can do it. Wishing you all the best. This is a great operation and Dr Gross and his people are fantastic.