Suspension travel limit - which bikes?

[William Doe]

Its of no concern to me really but my 5 cents worth 

I cant see a problem with the system as it is unless you happen to have a bike that's out of kilta ( ie have to fit spacers )

Rule seems to have worked ok since the get go .

The name pre 75 lends itself to a few issues if anything as some bikes are excluded in std trim even though they fit the year cut off .

Maybe calling the class classic instead of pre 75 and maintaining the 4 and 7 rule would be more workable 

Obviously then the YZbs and 74.5 Maicos go into pre 78

I don't think its broken though as it is ,

All  this bollocks about precision measuring etc FFS  as someone said "if you adjust the chain it alters the travel anyway .

Roscco asked a valid question as is his right and having met Ross hes not just a forum shit stirrer hes a genuine enthusiast racer who asked for clarification .

Unless you have a class for every 6 months or so through the period 1969 to 1984 then you are never going to please everybody  and after 1984 its not vintage anyway 

[09.0]

Sorry Ross but I think the last place to ask a valid question is on this forum! 

[worms]

your a cynical young fellow Brad, you can find the meaning of life here

see you at CD

[ksithumper]

Jeez,  five pages of arguing about shock travel?

You blokes need to get out more and just ride the feckin' things.

[Momus]

Several weeks ago I enquired of the VMX committee of AHRMA (and the silence is deafening) how to measure the travel on a leading link fork (LLF).  Teles are measured along the tubes, but that 7" of travel at an angle gives a smaller amount of vertical wheel travel. 

Do LLFs get measured 7" along the chord from full bump to full droop (somewhat like a telefork) or do you measure 7" of vertical travel as with a rear swing arm suspension?

Beats me.  I guess the tech committee doesn't know either.  Either way would be fine if I knew which one was preferred.

cheers,
Michael

You would logically measure the arcuate distance as the 7". That is the motion range through which the wheel is being controlled.  The same should apply for the rear.
However since we are not in the realm of needing space exploration and missile guidance accuracy, a standardised vertical movement measurement would be practical.

[Rossvickicampbell]

Brad - after 5 pages I find I really cannot argue with you  :'(  So much for 1/2 glass full eh!

[Tossa]

should have just emailed your local MA commissioner and ask him to clarify, make him work for a living!!lol

[Nathan S]

The point is that without a clear, defined way to measure travel, it opens up ways to bend the rules. It potentially also gives a vindictive scrutineer an avenue to bully a/any competitor.

People want to turn up with bikes they know are legal.
People want to race against bikes they know are legal.
Why does MA not want this?

[Nathan S]

I asked MA how to measure wheel travel a couple of years ago. I'm still waiting for a reply

MA GCR 16.15.10.2 says front wheel travel will not exceed 178mm (7 inches) rear wheel travel will be limited to 102mm (4 inches) measured at the axle.
Is that not enough info ?

No, it isn't. Not even close when top out springs and bump stops are added into the equation.

[Tossa]

The point is that without a clear, defined way to measure travel, it opens up ways to bend the rules. It potentially also gives a vindictive scrutineer an avenue to bully a/any competitor.

People want to turn up with bikes they know are legal.
People want to race against bikes they know are legal.
Why does MA not want this?

Scrutineer has no power to stop a bike entering an event, he has to report any thing that he believes not to be correct to the Clerk of Course.  The CoC makes the decision.

[KTM47]

should have just emailed your local MA commissioner and ask him to clarify, make him work for a living!!lol

No!!!!!  All correspondence or contact with the commission must go through the MA office. I asked this question of MA six months ago.

[KTM47]

The point is that without a clear, defined way to measure travel, it opens up ways to bend the rules. It potentially also gives a vindictive scrutineer an avenue to bully a/any competitor.

People want to turn up with bikes they know are legal.
People want to race against bikes they know are legal.
Why does MA not want this?

Any measuring must be done by a licenced measurer. Very few scrutineers are also licenced measurers. A scrutineer can knock a machine back at scrutineering bit that machine can be represented. Any exclusion is only done by the CofC and that decision can then be protested to the Steward.

[KTM47]

I asked MA how to measure wheel travel a couple of years ago. I'm still waiting for a reply

MA GCR 16.15.10.2 says front wheel travel will not exceed 178mm (7 inches) rear wheel travel will be limited to 102mm (4 inches) measured at the axle.
Is that not enough info ?

No, it isn't. Not even close when top out springs and bump stops are added into the equation.

Top out spring is not part of front fork travel.

Bump stops however can be and probably needs to be sorted out because there can be different length bump stops.

[GMC]

I asked MA how to measure wheel travel a couple of years ago. I'm still waiting for a reply

MA GCR 16.15.10.2 says front wheel travel will not exceed 178mm (7 inches) rear wheel travel will be limited to 102mm (4 inches) measured at the axle.
Is that not enough info ?

No, it isn't. Not even close when top out springs and bump stops are added into the equation.

Top out springs and bump stops come into the equation if they effect travel, if they don't effect travel then they don't come into the equation. What else does the ordinary guy need to know?

We can have rules like this...

Option 1
MA GCR 16.15.10.2 says front wheel travel will not exceed 178mm (7 inches) rear wheel travel will be limited to 102mm (4 inches) measured at the axle.

or Option 2...

Notice: From 2.6.2015, the Competition Practices Act Pre 1974 (Cth) has been renamed the Competition and Consumer Act 2015 (Cth) and is known as the Australian Competition Law. Matters previously regulated by the M.A. Racing Act and various State and Territory Competition laws are now governed by the Australian Competition Law which is administered by the M.A. state and territory consumer agencies and, in respect of racing services, by M.A. As a result, all references to the Competition Practices Act and State and Territory fair racing legislation in Old farts Law's publications should now be read as a reference to the Australian Competition Law. Competition Law is in the process of updating its publications accordingly.


4.4.0 The Competition Practices Act in reference to alleged racing class of Pre 75

4.4.1 The party of the first part shall be known as the ‘wheel’

4.4.2 The party of the second part shall be known as ‘travel’
‘Travel’ shall be known as a movement in the vertical sense

4.4.3 The party of the third part shall be known as ‘Motorcycle’

4.4.4. M.A. agrees that ‘Travel’ shall be of 7”/4” accordingly in reference to ‘Wheel’


4.4.5                     If M.A. and Entrant cannot agree within 30 days on the change to the specification of the ‘travel’ based solely on the changes to the Specification of said motorcycle, then the unit of ‘travel’ will be determined by arbitration in the nearest Pub.
 
 
4.4.6            The parties agree that the only two issues for determination in the arbitration are (i) by how much Entrants modification of the Specification for said 'Motorcycle' changes (positively or negatively) ‘Travel’ to make the movement of ‘Wheel’ and (ii) as between M.A. and Entrant, which party's proposed ‘Travel’ for the Motorcycle most accurately reflects the M.A.s specification of 7”/4” to make the ‘Motorcycle’ based on the modified Specification.
 
4.4.7            Five days prior to the arbitration hearing, each party will submit a proposed “travel’ for the 'Motorcycle' and a written brief to the tribunal and the other party setting forth the basis and rationale for its proposed increase.
 
 
4.4.8            Neither M.A. and Entrant may appeal nor challenge the enforceability of a final judgment or Award for reasons of personal jurisdiction.



And just for the record Rossco, yes this is sarcasm

[Michael Moore]

You would logically measure the arcuate distance as the 7". That is the motion range through which the wheel is being controlled.  The same should apply for the rear.

I know, but I figured mentioning that when it was not one of the methods that appear in the rule book would have been stirring the pot a bit much.    It would also be more difficult to measure at the track. 

Also, changes in rake angle will give a different vertical wheel travel with a telefork even though the swept travel hasn't changed.

Some rules give the impression that not all possible scenarios were carefully considered.  But in many, if not most, cases it is probably more important to pick one method, beat all the bugs out of that particular method, and then stick firmly to it.

While that may not eliminate all possible chances for one bike to have a slight advantage (or disadvantage) depending on variations in design of the suspension, at least everyone knows what is expected of them so there are no surprises when they get to tech inspection.

cheers,
Michael