If you look at it total, this is 9 rounds of 7/7/7, and 100/70 calories on the bike. So yeah, this is a lot. If need be, don't be afraid to scale that bike (especially) and don't hesitate to scale down to two rounds each segment on the 7/7/7. That way, this workout will take the desired 15-25 minutes to complete. The key is to just chip away. Find the movement you know you can catch your breath, and recover, then keep pushing.