If I use my current bikes that point is Oct 11. I can use recumbent and exercise bikes before then. I can even use a spin bike as long as I adjust the seat/bars to remain upright. I am limited to a 45 degree forward bend until 8-12 weeks post-surgery. There are some other restrictions like no squats, dead lifts, etc. Keep the weight down, no putting 120# on the bar. Isolate muscles so there is minimal strain on the back. But, overall within these parameters I can do work to rebuild muscle from atrophy.