Training for Chase the Sun angielski

Hi ,
I'm training for Chase the Sun, following the 4-month training schedule below. But it seems to me that this schedule is a bit light on the actual biking. It describes a weekly schedule. Initially each week has one day on a stationary bike and 2 days on a real bike. Eventually it goes to one day on a stationary bike and 3 days on a real bike. Why not more days on a real bike? Any thoughts?
Thanks,
Dirk