To gain mass you need to eat massive quantities of food and lift heavy weights...Here is a list of different reasons why some people are having a problem with gaining mass and fail to make any progress in weight training:

- not eating enough
- doing too many isolation exercises
- using machines instead of free weights
- not doing heavy compound exercises
- doing too many exercises too frequently
- not recovering between workouts
- doing frequent cardio and endurance

If your goal is to gain mass then you need to focus and put all your energy towards gaining mass. This means temporarily limiting or even eliminating long and intense bike rides and all other physical activities and sports which would interfere with your mass gaining goals.
It's physiologically impossible to become big and gain mass when doing frequent cardio and endurance activities.