Well if you run at 6 mph and ride at 18 mph then it is about a 3:1 ratio in distance. But in terms of energy used I would think the ratio is considerably higher. I can comfortably ride 100 miles at 18 mph, but I certainly can’t run 33 miles at 6 mph. I don’t do running, but Strava would probably provide a ballpark energy consumption per mile, which you could compare with your cycling consumption.