I just did a session of those intervals too. This was Monday's workout - 8x2 then 10x1. With me being old and slow I was only able to do 5.3w/kg and 6.6w/kg on mine. Tried to keep them at >135% for the 2 min and > 140% for the 1 min. Those intervals trashed my legs though. If it wasn't for the group ride last night I would have just cruised around in z1, I was feeling it!