Several years ago my husband had a bad motocross wreck. He broke his collar bone, had a serious concussion and his leg was temporarily paralyzed from the knee down.
Two weeks after the accident he started riding his spin bike. Clipped into the pedals, he spun with the good leg and the other went along for the ride. He supported himself with his good arm and added weight to the injured side as he healed. He was able to safely exercise until he was healthy enough to get back on the road. An unexpected obstacle and jolt could have aggravated his injuries and set back his recovery not to mention the danger of riding with a compromised body that may not be prepared to react appropriately when presented with said obstacle.
Have you thought about starting out on a spin bike?