Aftermarket Parts in Pre 75

[Nathan S]

OK, my take is (as a scrutineer in the past) that if you can't show me period evidence (mag sales ads with a pic - not a pic of an unobtainium works bike with similar stuff) of those aftermarket items you can't run them. We intended VMX to be glorifying old clunkers with their faults as a limiting factor (eg: 4" rear, 7" front travel, wimpy triple clamps, flexy swing arms, bendy forks, anaemic power etc etc) but then all the rule benders got creative in their search for the upper hand at the races.
This is why I've gone to Vinduro. Tony, it's a nice bike but it sure ain't period correct.

I still maintain that if reproductions of major components is allowed, then reproductions/replicas of works components must also be allowed.
If it so happens that the following year's production part is a replica of last year's works part, then it is actually VERY hard to mount a defensible argument prohibiting it.

NB: I don't want to do this, nor do I think that it would be good for the sport. But as the rules are written, only peer pressure stops it from being a common occurance.

[Marc.com]

OK, my take is (as a scrutineer in the past) that if you can't show me period evidence (mag sales ads with a pic - not a pic of an unobtainium works bike with similar stuff) of those aftermarket items you can't run them.

Good reason not to go to the hassle of turning up at competition event where they have gone nuts on scrutineering.

I am with Nathan, if it was available at the time whether it is off a works bike or whatever. If it existed in the world before 1975 then why not. Plus common sense should prevail.... for example is an alloy brake pedal really going to knock seconds off a lap time.

[EML]

Not if said alloy brake pedal is painted black-that's for sure, but if you leave it natural alloy it will every time-or so I've been told.

[VMX247]

For whatever reasons,

I suppose the same is occuring for the pre90 as we speak/write .
It was who and what clubs were around back in the begining of Classic Motocross in the structure/guidelines/construction of the gcr's and who was putting what into the rule book.
We can only ask and question our past vintage ethusisits of how this was/has come about.
Saying this, pre90 are the evolution of rule makers..go get em Rex 
cheers

[Nathan S]

I suppose the same is occuring for the pre90 as we speak/write .

I think that Pre-90 (and Pre-85) are happy to use age cut-off to gather bikes of an 'era' together.
Those classes don't seek to exclude any particular technology, that isn't automatically excluded by the age cut-off.

[VMX247]

I suppose the same is occuring for the pre90 as we speak/write .

I think that Pre-90 (and Pre-85) are happy to use age cut-off to gather bikes of an 'era' together.
Those classes don't seek to exclude any particular technology, that isn't automatically excluded by the age cut-off.

Nathan ,I hope they are still satisfied in another 20 years for what their foundation rules are laid down for here and now.There just aint pleasing some folks 
cheers
ps Nice bike Tony 

[Marc.com]

I think that Pre-90 (and Pre-85) are happy to use age cut-off to gather bikes of an 'era' together.
Those classes don't seek to exclude any particular technology, that isn't automatically excluded by the age cut-off.
[/quote]

I think also the pre 85 and 90 are not so open to issues of technology advantage.... pre 85 you start to get forks and suspension that works and finally pre 85 discs start coming along. Technically there wasn't as bigger leap between the after market and show room floor.

Probably due to the great work put in by the AMA to kill off works bikes.

[BultacoMacca]

What is people's view of "trick twin clicker suspension"?
I would have thought that only if its internally adjusted that it'd be ok for pre75.
Can't remember seeing any eternally adjusted compression or rebound pre75 shocks at the time.

[LWC82PE]

Im pretty sure Arnaco had external damping adjustment but pre 75 Firko?? I know there is one old brand like that which did have it, ive seen them on ebay.

Piggybacks are not allowed in pre 75 (probably except for Thermal Flows) so shocks with external damping knobs shouldnt be allowed in pre 75 either unless you can show proof of your shocks existance pre 75. I have not seen many people with modern shocks with external adjusters on pre 75 bikes anyway so i dont think its too much of a concern. EVO is where everyone goes crazy with modern shocks.

[firko]

I think that a number of American vintage part manufacturers are distorting history and therefore the appearance of pre '75 bikes by manufacturing and selling parts that have no resemblance of anything available back in the era. I don't recall seeing too many alloy swingarms prior to 1975 with the exception of Boyd and Stellings or perhaps Thor, the only billet triple clamps I know were made were the ProFab items shown below. All of those fancy billet backing plates, brake levers, torque rods and such stuff is pure bling that has no relevance to what was used circa 1974. In 1975 the trickest shocks you could buy were Arnacos or alloy Konis and there were no external clickers or any sort of adjustment with the exception of Arnacos having external dampening adjustment that really didn't make any difference. Fat bars are just plain wrong on pre '90 bikes let alonr pre '75.
I blame the soft cocks at the AHRMA who didn't nip this stuff in the bud when it first started to trickle onto the market. By turning a blind eye to it they're legitimising the stuff by default. The guys here see the stuff for sale on eBay or on the American supplier sites and assume the stuffs kosher by our rules as well. If some of this stuff isn't nipped in the bud pretty quickly our bikes are going to lose their period identity.
The only legal billet triple clamps to my knowledge ProFab, circa 1973-74

[firko]

Im pretty sure Arnaco had external damping adjustment but pre 75 Firko?

Leith, I've got four sets of Arnacos and they're all date stamped. Two@1972 and the others 1974.
They have external dampening adjustment and adjustable preload. They were years ahead of their time being true cartridge shocks before the others caught on. They're not perfect but they were the best you could get back then and worked well until the seals blew out. I've got a set on my Cheney that have had later style seals and some minor improvements done in attempt to prevent them leaking like buggery, their Achilles heel. I could have bought a set of Ohlins or trick YSS for what these will probably cost me by the time I've got them working right but I want to keep the bike period correct and prove that Arnaco was on the right course.

[Rossvickicampbell]

Firko - I am really reluctant to ask this because really some of the things mentioned don't have an impact on going faster or slower for the majority of us but as far as billet goes ie triple clamps - is there a problem with me making my own set of billet clamps now as I could of done in the day.

Don't get me wrong - I am really interested in the thread - don't have a strong stance on it (other than thinking period is the best way to keep the era clean) but wonder if some people take the concept too far down the line i.e whats wrong with a bling brake torque arm etc?

Please be gentle?

[firko]

Everyones got an opinion on this Ross, I'm only stating mine .
My objection to billet triple clamps and swingarms is that for every one of these little mods you do to your bike, it moves just that little further away from the era it's supposed to represent. I have no problem with you making your own triple clamps at all...as long as they replicate something that was made in the day. Theoretically you could make a set of 45mm forks if you had the right skills but would that be kosher?
My take on VMX is to imagine that the observer has hopped into the DeLorean, switched on the Flux Capacitor and gone back to 1974 (or insert era of choice). I feel that the observer deserves to see bikes that truly represent that era not bikes misrepresenting how it really was back them. Just my 2c worth.

[Marc.com]

but wonder if some people take the concept too far down the line i.e whats wrong with a bling brake torque arm etc?
Please be gentle?

hmmm alloy brake lever and torque arm were period RH250 components so there should be no issue there as they were around in the day. As were titanium bolts and axles.

Technically you can run whatever shocks you want as for good reason they are considered consumable .... like they were in the day. One way is to limit to designs that were available from each manufacturer, I mean Ohlins do their old style shocks still.

But you are right in that period bling only, so no 43mm forks on your pre 80 bike unless they are Fox.

[EML]

Firko, I have a pickle at the moment that you may be able to help with then. I am looking to buy new forks for my '76 RT15a Wasp. As it runs in pre'85 class I am tempted to buy and fit a later and longer travel front end but then it loses it's originality. However to fit the later model stuff makes good racing sense and it would still be "era specific" What to do?