50's: Good points -- Tons of mods available, a lot of people in the adult class, can ride in most back yards, cheap initial investment and can buy mods one by one, so it doesn't kill you pocket book. Not so good points -- Takes a lot of money make competitive in the mod class.
Mid size (mainly KLX 110's) Good points -- tons of mods available, you don't need as many as a 50, mainly just suspension and a 130 kit. The class is getting more popular (at least in SoCal). Fits an adult a little better than a fifty. Still takes a lot money to make competitive in the mod class. Can ride in most backyards. Not so good points -- takes a lot of money make competitive in the mod class. Not Red.
Big wheel Class (XR100 - XR200 in mini-frame) -- Can obtain big bike speeds, do big bike jumps, ride both mini tracks and and vet tracks, and main tacks, pass big bikes at will, Fits an adult the best. Race and beat big bikes. Not so good points -- Cannot be competitive unless you have a conversion. Initial investment for a conversion is steep. Popularity for racing isn't what it used to be.
All bikes have good points and they all cost about $4000 to be competitive (top five), but the 50's and 110's are cheaper to start with. If you get a big wheel to race, you should just buy a used conversion, unless you got big bucks.
Mini's Rule!
