Colossus is a former record holder for tallest K’Nex roller coaster. Not only was it the tallest, but it was also the fastest, reaching speeds of up to 65 miles per hour (29 m/s). "Particle Accelerator" is the current world record holder, standing 42 feet 2 inches (12.85 m) and traveling in excess of 80 miles per hour (36 m/s).(http://en.wikipedia.org/wiki/Knex)