Like other moto events the riders are brokendown into classes by skill and or age.
EXAMPLE:
Youth A&B, Novice (the beginner rider), Intermediate, senior, sportsman, senior A, advanced, expert, champ and vintage(determined by the bike pre 1983).
These are in order of precidence of diffaculty
THE BIKES
A modern trials bike is a porpuse built machine that is extremly light weight and very very powerfull most have five gears with Gas Gas offering six and full size bikes come in an assortment of sizes 125cc,250cc,280cc,300cc two and four stroke engines. many smaller bikes for the younger ones are offered even down to an electric bike great for the 3 & 4 year old riders.
THE RIDERS
There is no specific type of person who can ride trials anyone can do it! some time patience and pratice and you could be competing.
You will see all types of people riding trials tall, skinny, overweight, short, old and young the common thread between them all is having a great time with some great people.
It is awsome to see the family connection in trials whole familys ride together and not everyone has to ride to be involved and enjoy the sport. lots of family's share the fun by dad and daughter ride while mom observes(keeps score) at a section. It is not uncommon to see 60/70 year old dad still riding with his son and grandson (pretty awsome) that you wont see at a motocross!!!
THE COST
Trails is one of the least expensive motosports you will find!
Bikes last for many years as there is no need for a new bike every year to be competitve. All the big upgrades and engine builds are not a factor as most everyone rides a stock bike.
Tires are trials specific and can last for a couple of years and the same for clutches, brakes and chains.
Fuel no issue there either as you can compete all weekend with a two gallon can of gas!.
All of the info above is a general description.