I did 100% of the planned workout, it was not that difficult - but the intervals were not that easy either.
Details: 15 min warmup. 10 x (20 sec Right let, 10 second rest, 20 second Left leg, 10 second rest) in largest gear - my 54 x 13. Then, 20 x (30 second sprint, 1:30 ride) - again, all in the big gear.
Notes: the intervals were hard - especially about the 3-4th and the last few. I did them as hard as possible and reached 32 mph on a couple of them - which was hard in that big gear sitting down.