We have had many a great discussion on rules, regulations, eras, follow on's and in the spirit of, of this great sport and I would like to express my personel thoughts on the matter.
For those who know me and my bikes I like to keep as much as possible within the era Im riding in (including clothing within safety perimators)
I have run meetings (VMX) and the rules I have or want, usually get knocked (softened) back by my follow organizers' because I like the idea of the true ERA of the sport or the purest from of VMX.
My rules are very simple, maybe a bit harsh for most to take, but then that is the nature of rules and that is probably why I always like the idea of 'obsolutes' no questions asked "if it wasnt made/designated/manufactured/available or out of era the bike goes up an era to its most modern part.
"PRE" means exactly that. "Pre75" no follow-on's, no parts from post that era, excluding comsumables, which have to be of the same specifications within the boundaries of the era.
In 1974 you could not have any bikes or parts that were made in 1975 or beyond because they just werent there. Hence, Pre75 means just that, no ifs, no buts, no could haves.
My arguement for any era to have flow-on/follow-on models is that, if it wasnt made in the last year of that particular era then it couldnt have been raced that year. The bike needs to go up an era. And it is the same with any parts whether performance inhancing or not. This is Era racing not "but it is the same as that bike racing". Sorry, but you should have bought a bike of that era if you wanted to race in it but you are more than welcome to race your bike in the era it was made.
And it is the same with all the eras we race, from Pre60 through to Pre90.
This is just my personel opinion and no reflection on any rules or regulations that any club, organization or country has in place at the moment.
Yes, I do prefer the purist form of Vintage Motocross.