I tore a meniscus while running. I found that I could ride without pain even be surgery as long as I spun the pedals and kept my rump on the saddle. However I couldn't even walk without pain. After the surgery to scope out the tear, I could ride pretty soon afterwards. However I've never been able to run as well. In fact my knee hurts if I don't ride enough. Riding must strengthen up the muscles and stabilize the knee some.