I am short time for bike rides from work this week, so today I went for a Tabata protocol ride. After a 10 minute warmup, it's 8 sets of 20 second all-out sprint, 10 second rest. I used a nearby office park loop. The total ride time: 14 minutes.
Wow. I hadn't tried these on a bike before and it's been a long time since I've tried this sort of workout. I am going to have some deep muscle soreness tomorrow!