I'm flexible...from years of stretching so I have no need to stretch before I swim, bike or run. But I still stretch a few days a week. There's a quality difference between stretching pre-exercise to prevent injury and stretching to increase flexibility which ultimately will help prevent injuries. Since I'm flexible (comparatively speaking) I only stretch pre-exercise when I'm going to be performing certain exercises. But to increase and then maintain exceptional flexibility I'd have to stretch everyday 30 to 60 minutes. And I did that all through the '80s. Now I just do enough to maintain a reasonable amount of flexibility not the high level I was intent on achieving in the '80s. Sometimes when I haven't stretched and I feel tight I'll stretch. But I can't imagine going through life and feeling tight in an area and because I'd never stretch not realizing I need to stretch. Which leads me to the point that when you stretch on a regular bases you become more aware when you're pushing your muscles to a state of failure due to tightness/tears.
Bottom line, there's a reason gymnast, ballet dancers, football players, and CATS, stretch, it increases your range of motion thereby reducing their chance of injury. None of that you need to just ride a bike however stretching to improve your flexibility overall is definitely worth the time if done on a consistent almost daily basis.