Basically I just want to know which exercise builds more muscle and where does it build muscle, in your legs/butt.. etc ?

Before and after work out Stretching must u have do. It will help u to build muscle and for every workout u have to do only 5 to 6 verities in time being of 45 minutes to 1 hour

Both bicycling and rollerblading are cardiovascular exercises and don't build much muscle, but are great for you cardio health and weight management. If your goal is to build muscle - you should look into weight training.

On the other note - riding a bicycle you don't build muscle in butt (you sit on it :) but you do strengthen your quads and legs in general.

Wile rollerblading, you also strengthen the whole leg and get bigger cardiovascular workout in the same amount of time.

Hope this helps :)