Cycling is better than running for weight loss (the OP's question). Not because cycling burns more calories per hour- it usually does not. But you can do a lot more cycling without straining yourself or getting injured. For example, I rode 7 hours today, doing 3800kj of work. That's at least 3800 calories burned. Lets say that at an endurance running pace you burn 25% more calories per hour than cycling. That's still 5.5 hours of running.

Not many runners can do 5.5 hours and not have to take most of the next week off to recover. 5.5 hours is an exceptionally long run. Three hours is an exceptionally long run. Whereas I'm only slightly sore and won't even take a day off my training.

Of course if you love running (as I used to) and aren't yet too injured from running to continue (as I am), then there's nothing wrong with it.