Thank you all for your postings! I have found them very useful and enjoyable to use in my classes.
I have used this partnered tension drill several times with my spinning classes and they "love to hate it."
Have your class split into partners. The first partner will complete 30 revolutions @ 30% as fast as they can (either seated or standing) while partner #2 is at a "home" position, say 50% standing. When partner #1 is finished they will switch. When partner #2 has finished their 30 revolutions at 30% partner #1 will do 40 revolutions @ 40% as fast as they can go while #2 is at "home", then switch. Repeat at 50 revolutions/50%, 60 revolutions/60%, 70 revolutions/70%. If needed you can repeat it on the reverse...70/70, 60/60, 50/50, etc.
I have also done this same pattern around the room. Having only one person go at a time while the rest of the class is at a "home" position, or dividing the class into two teams and have them race.