Originally Posted by gregf83

Biking doesn't 'require' more time in the saddle but people generally do spend more time on the bike as it's enjoyable.
If you walked for 10 min before starting to run running would take longer too. There's nothing stopping you, other than perhaps traffic, from riding hard immediately. Two 20 min intervals at or close to FTP with a 5 min rest will feel definitely feel like a workout.