Cardio Does Not Mean You Can Eat More
It seems many people are under the impression that if you eat something bad or eat too much you can cancel it out by doing more cardio. This would be great if it were true but it is not true sorry to say.
Cardio doesn't just burn pure fat, it also burns some muscle. Also most machines or counters read a higher calories burned number than is in fact true. So eating a 300 calorie donut and then doing 300 calories on the bike doesn't equal out.
Now eating too much good food rather than eating bad foods does work a bit better in this situation but it still does not wipe the slate totally clean.
So keep your diet in check and remember that if you cheat it will hurt you still no matter what.