Perform this session with ERG mode on. Really concentrate to keep your cadence up above 90rpm after the warm-up. Don't allow it to drop between the 2min intervals or you will need to accelerate again back up to speed and waste extra energy. If you find that you struggle for leg speed and are in the low 80s or even into the 70s rpm wise, turn ERG mode off and do your best to maintain power but ensure you cadence is above at least 85rpm.