OK, I still have a question if maybe my ftp isn't understated.
Here is last night's 20 minute SST workout, on my road bike, no wind, pretty flat. I have my ftp set at 260 watts.
Peak 20 minute:
Normalized Power: 244 (94%)
Average Power: 238 (92%)
HR avg: 150 bpm, (84% max HR)
These workouts are not particularly hard. I would have expected higher exertion. What does your HR average (% of max please) for your workouts?