Motorcycle trials are most popular in United Kingdom and Spain. Nonetheless, they are also popular in other countries, like United States of America. Although they do not qualify for the most popular title there.

No such thing. Trials is a sub-sport of mountain biking, often called "mountain bike trials". It's a sport similar to motorcycle trials where one takes a light bike and hops around an obstacle course. You might have heard "BMX" and "trials" in the same sentence because a BMX bicycle can essentially make a good trials bike with minimal modifications.

The game Trials 2 is a very popular motorcycle video game for children and teenagers. The video game Trials 2 is a very cheap game which only costs about $4.95

Gas Gas is best known for their extremely popular trials bikes, although they also make successful enduro and quad bikes. It is a Spanish motorcycle manufacturer. They are leaders in the world trials market and are strong contenders in the enduro sector.

Motocross is a form of motorcycle racing held on enclosed off-road circuits. The sport evolved from motorcycle trials competitions held in the United Kingdom.[1][2] Motocross is a physically demanding sport held in all-weather conditions.