I'm 6'4" 250lbs. I love running and cycling.
I started running again about 2-3 months ago (I ran a lot until 8 years ago, best shape of my life actually (225lbs). Then I stopped, gained weight (280lbs), started cycling 4 years ago and lost some weight but still struggling). I currently run 3 times a week for a distance of 2 to 3 miles. It is helpful for my weight. I believe I can burn more calories by running 3 miles in a half hour than riding 7 miles in half and hour. The runners high is real and great. I still love to bike of course. At this point my cycling days have gotten less frequent because of running, but the weather is turning bad, and I prefer running to riding if it's raining out. At this point I don't know if the cross training is helpful for cycling, but I'm hoping it is.