Not a lot, bike riding is mainly about leg and and a little about back muscles.
If you look at a dedicated road bike or cross-country MTB rider you see them riding hunched way over forward.
Part of that is aerodynamics, but mainly it is because the upper body acts as a counterweight and provides an opposing force for the legs pushing down on the pedals. And it's that lean forward that puts a strain on the back muscles.
Riding out of the saddle, as MTBers do on difficult trails, or road riders when climbing hard will get your upper body more involved.
Horse riding will certainly tighten the muscles in your bottom and legs.
There several muscles and joints which are used when riding a bicycle. Some of them include wrist joint, knee joint, hamstring muscles, quadriceps and the calf muscles among others.
Yes, because you don't inherit the skill of riding a bicycle.
you will be riding a bicycle
I am not riding
A bicycle
That's all down to how hard you're riding. Most people will use more effort when riding IRL than riding stationary bikes.
poop
A bicycle helmet is a piece of protective headgear intended to be worn while riding a bicycle.
diamondback is a good bicycle for cruising, but not for extreme riding or jumping
You are not moving relative to the bicycle.
Just about any exercise will improve your fitness one way or another. Jogging or running is good for cardio and tones a lot of different parts of your body. Sit ups are good for you stomach area. Bicycle riding is good for cardio as well as your leg muscles.