Biking is probably the most environmentally friendly way to get from A to B. But if you fly with your bike to A and home from B, then all that beauty of biking is gone. I’ve done extensive travels across Europe by train, with and without a bike, I know it can be done. If you have time to read a book, then you have time to go by train.
Biking is good for you in many ways, not counting the obvious exercise. On great days you can cross three full valleys, you’ll see more than if you walked, and more details than if you went by car. Biking is a feast of input for the brain. I call it Brain Food. You get a lot of it while touring. Rivers, valleys, springs, mountains, houses, dogs, shepherds, deer, eagles, vultures, snakes, lizards, butterflies, fields of flowers, forests, and incredible roads. Some are masterpieces of engineering, while also being hard physical challenges. You can never take away the pride from someone who has biked over a real mountain pass in the Alps, or across a country, no matter how small.
It’s also an adventure. You’ll break speed records, crazy dogs might chase you, you’ll see all sorts of animals, insects can hit you like a ping pong ball smashed into your forehead. Bad planning can force you to bike through pitch dark mountains with the Milky Way above you. You can get to the edge of the Atlas Mountains in Morocco and wonder if you can see the Sahara Desert from there. And you’ll encounter friendly people taking you into their homes.
Biking is also a good way to lose weight. My experience is about 1 kg per week of biking. That loss seems permanent to me, and is despite adding muscles. The first days of biking can be tough, so be nice to yourself and don’t push yourself too hard. I average about 110 km per day on mountain roads, but the best distance is of course individual.
Finally, Credit Card Bike Touring is quite cheap since most of the time you’ll be out of big expensive cities. I typically spend about €90 a day when I travel alone, but it all depends on where you bike. If you are a couple, accommodation will of course be cheaper per person.