And efficiency! A human on a bicycle is more efficient than any other vehicle or animal. If we ran on gasoline, a cyclist would get the equivalent of roughly 1,000 miles per gallon. A well maintained bike drivetrain can reach 98% efficiency. Compare that to an ICE car which loses up to 70% of its energy to heat and friction.
A human on a bicycle is efficient because of mass and that the bicycle itself is a very efficient machine. A cyclist will burn around 30cal/mile of riding. If a gallon of gas has about 31.5k kcal of energy, then that's about 1,000MPGe for a human on a bike. A 200lb person + 20lb bike requires very little energy to overcome rolling resistance compared to a 2000+ lb ICE vehicle that spends the majority of its energy just to move its own mass.
https://www.scientificamerican.com/article/a-human-on-a-bicy...
Bikes are also a wonderful expression of physics, and the effect of centrifugal force is a key reason why cycling is special. The property of increasing stability with speed is amazing. Leaning not steering is also wonderful. The flow state you can achieve on a bicycle is unreal. Mind, body, and your physical environment in unison.
There's a mechanical beauty as well, that's easy to understand, but with plenty of depth to dig into and enjoy. Wheels and gear ratios are some of humanity's greatest achievements, and you get to pair that with interesting geometry and materials that have a direct impact on your experience. The difference between riding a junker that's not right for your body and a nice/fitted bike, is like the difference between wearing a burlap sack and a tailored suit.
Physical exercise is good, but bikes are much more than just a means to stay fit and produce endorphins. I wish everyone would bike more. Truly one of life's great joys.