I'd say that 15% is a conservative estimate, probably 25-30%. I still spin with the same cadence, but simply go much faster. So the workout is still significant and the ride is much quicker. If you are with people that know what they are doing it is very easy. IMO a 5 minute pull is kinda long when in a group. Pull for a couple minutes then rotate. I'm no expert but this is what i've seen from my humble experiences. Everyone pulls for a little while and everyone stays fresh.