I am just over 4 months out of ACL surgery. I had a patella tendon graph. I went to PT 2 X a week for a couple of months where I did lots of leg exercises. Outside of that I did a lot of push up, pull ups, sit ups, shoulder presses and pedalling the stationary bike on my own. At 2 months I was back to running and stated squatting with weight again. I am about at 90% of my presurgery 1 rep max for squatting right now. Still can't do a pistol squat though
Doc said I could start riding at 4 months if I wanted to, but my mechanic has been slacking on getting my suspension done so I haven't gone yet....
This is my second ACL surgery - matching scars now. What worked best for me was to keep moving - even if I had to do it sitting down. MY PT was very cautious, but my doc was supportive and let me know exactly what I could and couldn't do. I figured since he was the one who put me back together he knew what he was talking about. Check with your doc before doing leg extensions - my doc said no open chain exercises during healing.