If you want something that destroys your legs and cardio, find one of those bikes with the fans on the wheel that makes it harder to pedal the faster you go. Set a timer for 5 minutes, pedal normally for 30 seconds and then sprint(as in push physically as hard and fast as you can) for 30 seconds and keep switching every 30 til the time runs out. If you do it right by actually pushing yourself as hard as you can during the sprints your legs should be wobbly as shit when you try to walk off the bike.
Obviously you're going to have to work on a different part of you body before you do another round on the bike.