Muscle catabolism requires a deep and prolonged caloric deficient, near starvation in fact. This is fear that seems to have been hyped by body building magazines and protein supplement companies. Normal fasted training will not result in muscle catabolism. You have adequate fat reserves to handle a 3 hour easy ride. Consuming any calories before exercise means that session will not be done in a fasted state. Excessive protein above what is needed for health results in a process in the liver called gluconeogenesis where that protein is concerted to glucose. So excess protein consumption is like eating more carbs. Long duration low intensity bike rides should up your protein requirements and I doubt you’d see any recovery benefits from that.
There is a good bit of controversy over the amount of protein needed for health by athletes. Some research on Google will give you that range.