True what Bruce is saying, but also pure protein is a meal replacement, additional carbs, etc, whereas the 'whey protein' shake is more specifically for adding only protein to your diet. Even though, this would not be adding much weight if used only after exercise. Rather check your eating habits (portion size, frequency, etc), vs your exercise type, sure you're cycling, but at what heart rate etc. And then, as Bruce suggested do a daily calorie balance, and you should have an idea where there is room for improvement.
