I did a similar workout last week on a 7% grade. I rode it in a 50/17 gear, 5 min on then 5 min in a 34/17 maintaining the same cadence and keeping constant pressure around the pedal circle. I did 3 reps like that and hope to move up to 4 this week. It's a tough workout and not one I want to do more than once a week for sure.