Trials riding evolved from motorcycle riding in Spain and the emphasis is on bike-handling skills, rather than speed. Competitions generally involve negotiating a course with man-man and natural obstacles without putting your feet on the ground.
Trials bikes often have powerful brakes for hopping on uneven surfaces, wide handlebars, light parts, a low gear ratio for quick acceleration, a thick, grippy rear tyre, a low frame, wide handlebars and no seat (depending on the make) so you can flick the bike around, hops, jumps and perform a wide variety of tricks.
20" (Modified)
These tend to have a single gear and a large rear tyre. They were originally created by modifying the standard BMX bike to be more versatile for stationary balance-orientated tricks rather than fast-paced jumps.
26" (Stock)
This type originally evolved from the standard Mountain Bike, however these days they are designed specifically for trials riding with at least six gears. The seat is often removed to save weight because the rider doesn't need one when competing.
