Mach Rider happened in 1985.
Mach Rider was created on 1985-10-18.
Taxi Rider happened in 2000.
Line Rider happened in 2006.
GP Rider happened in 1990.
Crazee Rider happened in 1987.
Kung Fu Rider happened in 2010.
Knight Rider Special happened in 1994.
Rhyme Rider Kerorican happened in 2000.
Knight Rider - video game - happened in 1988.
Super Rider - video game - happened in 1983.
The mach number is the speed, compared to the speed of sound in air. Thus, mach 1 is the speed of sound, mach 2 is twice (2 times) the speed of sound, mach 3 is 3 times the speed of sound, etc.
There is no plural for the noun 'mach'; the different levels of mach are usually shown by a numeral for various speeds, such as mach 1 or mach 2.