Why are spanish riders so successful?

Also why arent there more asian riders , as I've heard they used to be dominant in the 90's and they have honda suzuki and yamaha , not to mention kawasaki.

It really all comes down to the racing series' available at the national level, back in the late 80’s and early 90’s Japan had arguably the best national-level motorcycle racing series in the world, the All Japan Road Racing Championship, the series ran 2-stroke grand prix bikes including a 500cc class. It was one of the best ways for young riders to get into the world championship, and promoted a lot of Japanese talent. So by the mid 90’s the 125cc, 250cc, and 500cc championship was full of Japanese riders, and by the start of the 2000’s Japan even had 2 races in MotoGP; the Japanese Grand Prix at Suzuka, and the Pacific Grand Prix at Motegi. But as the Japanese series phased out the use of grand prix bikes, new series’ in Europe began to take its place, the CEV Repsol championship run in Spain uses grand prix equivalent bikes, and crucially race on a lot of the circuits that appear on the MotoGP calendar, so naturally the junior and intermediate class starts to fill up with Spanish talent, and these riders eventually make their way to the premier class.

But now we have the Asia Talent Cup which runs each year, and that has helped promote a ton of Asian riders into the Moto3 class, and a lot more young Japanese riders have made the trek to Europe to race in CEV Repsol and the Redbull Rookies Cup. With Ai Ogura, Kaito Toba, Tatsuki Suzuki, Ayumu Sasaki, Yuki Kunii, and Ryusei Yamanaka, on the Moto3 grid, it's only a matter of time before they reach MotoGP. There’s also Tetsuta Nagashima in Moto2, and if he can work on getting more consistent, he has a decent shot at getting signed by a MotoGP team.

/r/motogp Thread