a. The craze started in Canada.
b. The craze was started for Canadian ice hockey players so they could train during the summer time.
c. The blades were changed for wheels because the skaters could not train in the summer time on the lakes and rivers they used to train on anymore and the wheels helped them exercise on the road.
d. The advantages of roller-blading are the speed and agility, that is similar to the one of ice-skates, and the fact that you can do it in the street.
e. Roller-bladers can go with a speed of up to 30 miles per hour.