interesting. when i was 16 tried my brothers Kawasaki (i think it was an AR) 50cc. At 17 went and bought a Yamaha RD 250 LC which would do about 105 mph. then proceeded to smash the bike and my body being a clever f***er taking a bend far to fast and way above my ability. stupid thing is i then got a Honda superdream Honda should have named it nightmare for the handling and did the same thing. my father pointed out it was not the bike but the bikers ability to know his limits and the bikes so he limited me to a yam dt 100 for 6 months then Kawasaki ke 175 then Suzuki gt 185, then to rd 250cc 400cc cb 550cc cbr 600cc gsxr 750cc and toped out with gsxr 1100. R1. now ride a ccm 650 xtz 750 and dr 250. so worked my way through the and believe i am a competent rider. if the 125 limit was i place then and graduating to bigger bike policy was in place i am sure i would not have had the accidents. but i agree you would not let anyone but L plates on a car and drive unsupervised. so i believe the correct way is to take a rider training course ex amount of hours or instructors to pass you to ride solo. i have been living in eastern Europe for the last 10 years and most counties have a mandatory hours of instruction then full bike test which comprises extensive theory and then police examiner to pass test. however here in Romania they have the highest bike fatality in Europe due to riders fault.
so does this prove it is just the individual.
but agree so of the best fun riding has been on small cc bikes.
mike.
remember a bike has one fundamental design problem, it will not stand up by itself.