OzVMX Forum
Clubroom => General Discussion => Topic started by: Rossvickicampbell on May 31, 2015, 10:24:55 pm
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Gents - which bikes are affected by the suspension travel limiting rules - both pre and post 75. I know the YZ Bs in pre 75 have to be limited - what bikes after that and which eras please?
thanks
Rossco
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YZ B, where on sale here in Australia, easter 1974, I think the rule to limit them is just crazy, I never agreed to it in the first place.
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In pre 75 the 74 Maico's where the first production MX bike with forward mounted shocks and they had about 6.5" travel. Also the the YZB as you mentioned had a similar amount. These bikes where forgotten about when the pre75 class was thought about as it was meant to be for bikes built before the long travel revolution. The 4" travel in the rear is a bit silly because almost all the bikes in the era had close to 5" at the wheel and 4" travel shocks. So all bikes built around 73-74 have to be limited to meet the rule as written.
Not sure about the ones in pre 78 but there are a couple that exceed the 9/9 inch rule.
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This was asked a while back. If my memory serves me correctly...
The following 1977 models were factory specced with more than 9" of travel at either end:
1. RM125B;
2. YZ250D;
3. YZ400D;
4. Montesa (all MX);
5. KTM (all MX);
6. Husqvarna (all MX);
Can't recall for SWM, Bultaco or Ossa, and I have a vague memory that one of the Euro brands' enduro bikes were over 9" too.
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The thing is , how is travel really measured? Suzuki typically do not offer the claimed travel in the brochures unless compression/partial compression? of the rebound spring on top out is taken into account. I measured some stock 77 RM250 forks to have 213mm (8.38”) and the specs say it should be 220mm (8.66”) I could not physically compress the rebound spring by extending the forks by hand. I have found this to be the case with several other Suzuki forks too. So if your bike was checked at the races how would they do it? I cant imagine having to pull apart your forks measuring rebound spring and saying ok we think that would compress X amount and then add that onto the measured travel. So what I am saying is that there could be some bikes that have above 9” in the specs but when measured by just collapsing the forks they pass as having under 9” of travel and only actually measure above 9” if the rebound spring compression is inc. So what is a fair and consistant way of determining the travel?
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The thing is , how is travel really measured? Suzuki typically do not offer the claimed travel in the brochures unless compression/partial compression? of the rebound spring on top out is taken into account. I measured some stock 77 RM250 forks to have 213mm (8.38”) and the specs say it should be 220mm (8.66”) I could not physically compress the rebound spring by extending the forks by hand. I have found this to be the case with several other Suzuki forks too. So if your bike was checked at the races how would they do it? I cant imagine having to pull apart your forks measuring rebound spring and saying ok we think that would compress X amount and then add that onto the measured travel. So what I am saying is that there could be some bikes that have above 9” in the specs but when measured by just collapsing the forks they pass as having under 9” of travel and only actually measure above 9” if the rebound spring compression is inc. So what is a fair and consistant way of determining the travel?
I was the MA measurer at the Classic MX Champs at QMP in 2012.
Forks:- It was just a matter of removing the fork springs and measuring the travel from compressed to extended, with a ruler or tape measure. I didn't try to compress the top out spring etc. I allowed a 5% tolerance because of the method of measurement etc. So 9" is 228.6 mm add 5% it is 240 mm. If you are over that you are well over. Aim for 229 mm. Also we are measuring the travel of the forks not the vertical movement.
Rear end:- Again shock springs off and can be just the one shock left on. Put bike on stand, take any sag out also, measure from centre of the axel to a point vertically (90 degs) up to somewhere on the frame. Take the bike off the stand and compress shock to bump rubber. No need to try and compress bump rubber etc. Measure from axel centre again to same point on the frame. The difference is the travel. Also note the position of the chain adjustment can influence the travel slightly. Aim to be slightly under the 229 mm that way there is no surprises.
I'm sure someone will try to tell me I did it wrong. They are more than welcome to apply for an MA measurer's licence and do it next time.
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This was asked a while back. If my memory serves me correctly...
The following 1977 models were factory specced with more than 9" of travel at either end:
1. RM125B;
2. YZ250D;
3. YZ400D;
4. Montesa (all MX);
5. KTM (all MX);
6. Husqvarna (all MX);
The Maico is too long as well.
More bikes than not, need to reversed engineered to comply. Its one of those rules that allot thought did not go into. IMO they should just have no rule for suspension travel in pre 78 the same as evo.
Can't recall for SWM, Bultaco or Ossa, and I have a vague memory that one of the Euro brands' enduro bikes were over 9" too.
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Kevin, your method is perfectly reasonable and logically sound - but is legally indefensible if someone wanted to push the point. Not because you're method is wrong or unfair, but because you've been forced to invent a method that is not in the rule book.
Properly written rules are the real solution.
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thanks - and does anyone know where the logic behind limiting the bikes mentioned has come from? If I can remember rightly, and that is doubtful, there was an MA comment re everyone wanting to buy the bikes with the most travel and the other makes being "left behind" as a result? I challenge this logic as for the YZBs there were only 1200 or so 360's made with probably 20 in Aus at best so everyone is not going to jump on that band wagon.
I am thinking about putting in a request to the MA commission to remove the limit rule but wanted to know what bikes were effected and what the logic behind the rule was?
cheers
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Oh Christ, here we go again, just what the forum needs, another rule rehash!
Pre 75 was originally put together for the old school short travel bikes.
The intent was to celebrate the Era of short travel bikes, not just the year.
It was defined as Pre 75 without thorough research and it was then realized that some Pre 75 models had more than 4” travel.
At first there was some attempt to ban these bikes as they were the odd ones out with the short travel bikes but after much debate they were allowed in with restricted travel (which seems like a sensible option)
Decades later we now have guys crying foul that they have to modify the travel of their bikes to fit in with all the other short travel bikes.
Vision of the future;
Long travel bikes are allowed into Pre 75.
Long travel Maico’s are now sought after as 6” rear suspension is far superior than 4”
Fast guys will win on anything.
All the fast guys choose the long travel Maico’s so they can beat the other fast guy.
Maico’s are now hard to find.
GMC buys a welding robot and starts spitting out replica Maico frames
People fit other engines into the replica Maico frames.
The start lines are full of Maico framed Suzuki’s and Honda’s and Bultaco’s and Yamaha’s
Then some bright spark wants to fix the Maico framed bias of the start grids and allow modified laid down shocks on all Pre 75 bikes.
People start parking their bikes rather than butcher them to try and compete
The Era of short travel bikes is now lost forever[/i]
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I guess a quick Email to [email protected] could be the solution
thanks - and does anyone know where the logic behind limiting the bikes mentioned has come from? If I can remember rightly, and that is doubtful, there was an MA comment re everyone wanting to buy the bikes with the most travel and the other makes being "left behind" as a result? I challenge this logic as for the YZBs there were only 1200 or so 360's made with probably 20 in Aus at best so everyone is not going to jump on that band wagon.
I am thinking about putting in a request to the MA commission to remove the limit rule but wanted to know what bikes were effected and what the logic behind the rule was?
cheers
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thanks Dave - appreciate that.
Geoff - can see you woke up on wrong side of the bed today? It isn't just pre 75 but later eras as well? And what is wrong with simply asking a question or finding out what the logic is? Few new faces on the commission now so no harm in asking. And bugga me - a guy even expresses a comment about thinking of doing something formally - which isn't that what we all preach on here - and somebody has to get all sarcastic and facetious about it????
Damned if you do - damned if you don't. And don't dare ask a question on here apparently.
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Sorry Rossco, guess I have been on here too long and seen the same questions too many times.
You can apply formally if you like and I didn’t see my post as being sarcastic, just factual as I do believe the vision would happen in the space of a few short years.
As for the later Era’s I believe the Pre 78 class was meant for the early long travel bikes.
I assume they went through the same thing of banning bikes which had more than 9” or letting them ride with restricted travel
There will always be debate on this one as it is certainly debatable.
Comes down to the same question, do we celebrate an Era or do we celebrate a particular year?
Thing is, the guys that complain about the pre 78 travel are the ones that would only buy a 77 model to have the technological upper hand which is why I believe my pre 75 vision would happen.
(steps back now to avoid all the flack)
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Our Pre-78 class was apparently a direct copy of an American class. That class has since changed to recognise and allow the 77 models with more than 9" of travel, but we have not followed suite.
Pre-75 was always about the short travel era, who's death began with the YZ-B and 1974.5 Maico. So while those bikes (and the 1974 KTM motocrossers) ARE legitimately Pre-1975 models, the class was always intended to exclude them (hence the travel limits).
I have no problem with this.
However, to exclude these bikes from racing in standard form in Pre-78 is absolute idiocy.
Pre-78 is less clear cut. The rules appear to be written on the assumption that no Pre-78 bikes had more than 9" of travel - and 9.5" or 10" is still clearly short of the 12" that became the norm in the Evo era.
Once again, the rules are not clear - and once again our peak body (the MA CMX/CDT Commission) is not providing leadership on the issue.
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Kevin, your method is perfectly reasonable and logically sound - but is legally indefensible if someone wanted to push the point. Not because you're method is wrong or unfair, but because you've been forced to invent a method that is not in the rule book.
Properly written rules are the real solution.
Ok smart arse. How do I measure the travel accurately without having a tolerance. The engine capacity for Classic racing has a 5% tolerance, that is where I got it from. The one bike that was excluded in 2012, was about 25mm over the 229 mm limit. Top out spring has no real bearing on usable suspension.
Pre 75 has had the current limits for years now, while I personally don't like it I wouldn't try to change it. As for Pre 78 I personally think 10" (254 mm) would be better. Anyway if you want to change it read the MOMS. It can't be changed until next years commission meeting. March 2016. Posting about it here is not going to change it.
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Ross unfortunately it has become the norm on the forum for eligibility issues to turn into a bunfight, however this one has stayed relatively civilised. Your question is legitimate, and as Dave says put your query to MA.
With all rules, lines have to be drawn in the sand and they don't always suit everyone. The suspension travel limits have worked well I think and have helped to keep less advanced bikes in the game. I had my '74 Maico rear end limited and it was no biggie. If the limits are left open I think Geof's scenario is not that outlandish.
Kev you are a stickler for accuracy, and with that in view I am surprised you claim to have been the measurer at the 2012 Classic Nats.
Chief scrutineer was Kerry Marsh, assistant scrutineer Michael Vandenbroek, technical adviser Dave Tanner. Tanner did the measuring.
Sources are Sup regs, stewards report, C of C report, and my recollection as event co-ordinator. This is not a comment on your knowledge or expertise.
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Top out spring has no real bearing on usable suspension.
I would agree with this too, that's why i am curious as to what bikes are on the pre 78 'must be restricted list' only because of their advertised/over quoted brochure travel and if they actually have travel measured by MA scruitineer method they would/could quite possibly pass under the 9" limit. I have proven Suzukis don't match what the specs say unless you inc the added travel on rebound, but are other brands like this too?
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Don't rely on the specs stated. Check for yourself. Any measuring of bikes should be done by a licenced measurer.
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"Anyway if you want to change it read the MOMS. It can't be changed until next years commission meeting. March 2016. Posting about it here is not going to change it."
Excuse me - who said anything about changing it before 2016 - who said anything about trying to change it before next years commission meeting. I happen to be a 1/2 glass full person and thought I might do some homework before I even thought about putting in a submission! No time frames entered into. I think the forum - generally - is a place where I learn lots from - this happens to be the first time I have broached something from the MOMS/MA or whatever you would like to refer to.
I understand what the rules are and limit my YZB to suit and have done for years now - doesn't make me any slower :D - however often wonder why we cannot simply ride them as they came out at the time - Geoff's thoughts taken into consideration here and honestly hope he is wrong. But I am forced into restricting it or cannot ride it - can't go up a class or era.
I have written to the technical services - even if the email address you gave me Dave didn't work ;D - so will look through what I get and have a thought.
Just someone keen on the sport asking some questions - sorry Geoff if they have been asked before ;D but rather than debate it here was after info to question it the correct way.
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Is Dave a MA licenced measured? So the tape I borrowed from Michael Banford and still have wasn't used to measure suspension travel. Check your facts and then post your apology here. I wasn't measurer before the meeting, but apart from the Seward who can't do it I wasn't the only other one licenced to do it.
If you/MA are using tapes, presumably printed, for a precision measurement, that worries me.
Generally tape measures are for reference only.
I would like to think that certified scrutineers would at least be using an independently calibrated steel ruler or a set of certified Vernier calipers if there were a chance that things could go to the Steward or beyond.
When you say "... compress shock to bump rubber. No need to try and compress bump rubber etc." that seems expedient. The bump rubbers on my Pre 78 bike are urethane foam and about 35 mm long. They function as a rising rate auxillary spring with a little damping.
I could have the legal 229 mm plus 50 mm in the stops allowing for the motion ratio.
Surely the test requirement should be a measurement with bump rubbers completely removed?
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I'm sorry, I seemed to have wandered into parliamentary question time.
I'm looking for the site where adults (mainly like minded men, FFS!) talk about old motorbikes.
The dodgiest ruler I've seen in my life would be accurate to a mm (maybe 2) over 240mm
A "calibrated" ruler! "Vernier calipers".
Maybe if you think you came second in the world championships because the guy that beat you had 4mm extra travel.... Put your money down (in case it turns out to be legal, and you pay costs) remove the bump rubbers (not a 5 minute job, not a job that could be done at the track I'd suggest.) while waiting for the calibrated rule to be warmed/cooled to the correct temp.
Anyone know where I can get a radiator guard for an '81 RM125? Or suggest a mesh that doesn't inhibit the airflow too much.
;) :P
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Wouldn't you just put the bike on a stand with both wheels in the air and measure from top of the wheel to the underside of the guard. Shock shaft length would differ depending on it's position on the swingarm.
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If you/MA are using tapes, presumably printed, for a precision measurement, that worries me.
Generally tape measures are for reference only.
[/quote]
Tape measures are used by tradesman it depends on the tolerance needed.
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I agree with Rosco , In all the travel bun fights that has been on here this one might just answer some of the questions . I race (wobble ) in pre 70 , 75 , 78 . Im building a YZb250 up but will not race her in the Nats . My 77 YZd's are great bikes all the go fast gear from the era White Bros swing arms and fork internals so they don't go to the Nats they are what I wanted in the day , I race my 76 yz'c for pre 78 in pre 75 I use MX'ers . When I do race its for fun but when I build I build to the best one could buy in the day as that was what I wanted back then .
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KTM47, The point is that there's no defined way to measure the travel. Without it, EVERY conceivable method of measuring travel can be shot down.
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Not really.
I think if someone has an abnormally long bump stop I think that needs to be considered, but measuring travel without the bump stop is just not practical.
For rear wheel you are measuring rear wheel vertical travel. As I said the position of the wheel in the swingarm (chain adjustment) does have an affect. All the way forward less travel all the way back slightly more travel.
Either way a tolerance needs to be stated.
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Wouldn't you just put the bike on a stand with both wheels in the air and measure from top of the wheel to the underside of the guard. Shock shaft length would differ depending on it's position on the swingarm.
That's not accurate, many bikes bottom before they hit the guard. You can bolt longer shocks on with the same shaft travel and increase the gap between the tyre and guard but not increase the wheel travel..
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John. Who measured your suspension travel at QMP in 2012?
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If you/MA are using tapes, presumably printed, for a precision measurement, that worries me.
Generally tape measures are for reference only.
Tape measures are used by tradesman it depends on the tolerance needed.
[/quote]
Mate, I am a tradesman and I sometimes make suspension parts for cars.
For this type of work if you are going to measure 229 mm you reach for a steel ruler or calipers; the good old tape measure probably has a millimetre or more of slop in the hook rivet.
In your defense the tolerance is very generous but it also highlights the lack of precision and rigor in the whole exercise.
Not really.
I think if someone has an abnormally long bump stop I think that needs to be considered, but measuring travel without the bump stop is just not practical.
For rear wheel you are measuring rear wheel vertical travel. As I said the position of the wheel in the swingarm (chain adjustment) does have an affect. All the way forward less travel all the way back slightly more travel.
Either way a tolerance needs to be stated.
My bump rubber is off the shelf Ohlins.
Don't the AMA use 10% of the bump rubber's free length for their calculations?
Measurement logically should be in the mid point of the chain adjustment range.
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Like Wasp said, shock builders ignore the bump rubber when measuring travel. That's how Ohlins do it..
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John. Who measured your suspension travel at QMP in 2012?
I think Dave did, I walked away and left them to it. .
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Gents - which bikes are affected by the suspension travel limiting rules - both pre and post 75. I know the YZ Bs in pre 75 have to be limited - what bikes after that and which eras please?
thanks
Rossco
sorry Rossco, looks like Bill and Ben and the flower pot racing men, have got a hold of your topic, it was a really easy question.
cheers worms,
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Wouldn't you just put the bike on a stand with both wheels in the air and measure from top of the wheel to the underside of the guard. Shock shaft length would differ depending on it's position on the swingarm.
That's not accurate, many bikes bottom before they hit the guard. You can bolt longer shocks on with the same shaft travel and increase the gap between the tyre and guard but not increase the wheel travel..
That's right, but it can also work the other way, a shock with more than 4 inches shaft travel does not always equate to more than 4 inches wheel travel. There are a lot of variables when trying to calculate WHEEL travel by measuring shock shafts... the rule calls for WHEEL travel not shock length/travel, so wouldn't it be simpler and more accurate to measure the distance between the wheel and underside of guard, this would give you the actual distance the wheel can travel.
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Not measuring shock travel. Measuring wheel travel.
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John. Who measured your suspension travel at QMP in 2012?
I think Dave did, I walked away and left them to it. .
No I did. I am a MA licenced measurer. No one will get a measurer's licence unless they have suitable trade qualifications.
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Not measuring shock travel. Measuring wheel travel.
while we are talking about these travel limits we need to take into account swingarm flex as well
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so you guys were measuring wheel travel, wow,
at who's request?
yours, the stewards or the CoC, who's?
so being a bunch of so and so's, before a protest is made is in the best interest of the sport, really.
your not a cheat until you've competed. I dont get the mentality of it all.
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Wouldn't you just put the bike on a stand with both wheels in the air and measure from top of the wheel to the underside of the guard. Shock shaft length would differ depending on it's position on the swingarm.
That's not accurate, many bikes bottom before they hit the guard. You can bolt longer shocks on with the same shaft travel and increase the gap between the tyre and guard but not increase the wheel travel..
That's right, but it can also work the other way, a shock with more than 4 inches shaft travel does not always equate to more than 4 inches wheel travel. There are a lot of variables when trying to calculate WHEEL travel by measuring shock shafts... the rule calls for WHEEL travel not shock length/travel, so wouldn't it be simpler and more accurate to measure the distance between the wheel and underside of guard, this would give you the actual distance the wheel can travel.
No because I put longer shocks on my pre 78 RM's because I'm tall but they still only have 9" travel and 10" clearance..
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John. Who measured your suspension travel at QMP in 2012?
I think Dave did, I walked away and left them to it. .
No I did. I am a MA licenced measurer. No one will get a measurer's licence unless they have suitable trade qualifications.
Your telling use that MA have given a license for suspension travel measurements!
In the early days of vintage they used to get Firco(Sorry Mark) to bounce on the seat to check the travel with a tape measure of all things. On one occasion fork diameter had to be measured and someone came up with a vernier for that.
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Ross unfortunately it has become the norm on the forum for eligibility issues to turn into a bunfight, however this one has stayed relatively civilised. Your question is legitimate, and as Dave says put your query to MA.
With all rules, lines have to be drawn in the sand and they don't always suit everyone. The suspension travel limits have worked well I think and have helped to keep less advanced bikes in the game. I had my '74 Maico rear end limited and it was no biggie. If the limits are left open I think Geof's scenario is not that outlandish.
Kev you are a stickler for accuracy, and with that in view I am surprised you claim to have been the measurer at the 2012 Classic Nats.
Chief scrutineer was Kerry Marsh, assistant scrutineer Michael Vandenbroek, technical adviser Dave Tanner. Tanner did the measuring.
Sources are Sup regs, stewards report, C of C report, and my recollection as event co-ordinator. This is not a comment on your knowledge or expertise.
Col I accidentally deleted one of my posted. Anyway I was asked to do the measuring at QMP in 2012. Apart from the MA Steward to my knowledge I was the only other person there who has/had a measurer licence. I was only asked at the last minute. You can not get a measurer's licence unless you have suitable TRADE Qualifications. You can post your apology here.
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so you guys were measuring wheel travel, wow,
at who's request?
yours, the stewards or the CoC, who's?
so being a bunch of so and so's, before a protest is made is in the best interest of the sport, really.
your not a cheat until you've competed. I dont get the mentality of it all.
Maybe you should read all the posts. The suspension travel was measured after the third Moto in the impound.
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Wouldn't be many 'eligible' pre-75 bikes if the total rear wheel travel was measured without the bump stops. :o
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Two of my bikes were measured by Kev in impound and another was measured in the pits after someone complained that my Maico did not comply. I was asked to clear the air and I allowed him to do so.
I'm sorry Ross but I look at this thread with a bit of cynicism as you have been on here a long time as I have and seen this question asked and argued many times, with you being in the thick of it seeing you have one of the bikes on the list that have to be restricted.
I can't help but wonder why you would bring this up yet again.
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Wouldn't be many 'eligible' pre-75 bikes if the total rear wheel travel was measured without the bump stops. :o
If the swingarm , and shockmounts are original AND the shock length is no more than 340 mm , then there is no option to exceed the 102 mm travel . Very simple .
If the shock has 102mm of travel and all is original then the wheel will have more than 102mm of travel making it not legal. If the shock was mounted on the axle and mounted close to vertical then the wheel would match the shock but I haven't seen a bike like that yet.
My method to measure travel is to remove a spring and fit that shock only. Let the bike sit fully compressed under it's own weight. Take a measurement from the axle to a fixed piont verticaly above then lift the bike and let it hang. Take another measure and the difference is the travel.
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The rules specify wheel travel. Shock travel is just one of the factors that determines the wheel travel.
We are having this discussion again because leadership is missing.
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The rules specify wheel travel. Shock travel is just one of the factors that determines the wheel travel.
We are having this discussion again because leadership is missing.
I think we are having this discussion again mostly because some don't agree with the rules. It's not as though they are not clear enough now.
You are pushing an issue regarding accuracy and method. Method if you ask those that police it (that's what I did) is as per Kev.
Accuracy is within a percentage which would soak up those badly made tape measures that I use every day to make a pool level and measure minute gaps in tiling.
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the good old tape measure probably has a millimetre or more of slop in the hook rivet.
[/quote]
Tape measures are supposed to have that slop at the hook
The movement of the hook is meant to be the equivalent of the thickness of metal of the hook so that you can get an accurate measurement whether measuring inside or outside of an object
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the good old tape measure probably has a millimetre or more of slop in the hook rivet.
Tape measures are supposed to have that slop at the hook
The movement of the hook is meant to be the equivalent of the thickness of metal of the hook so that you can get an accurate measurement whether measuring inside or outside of an object
[/quote]
I know. Rivets and holes wear and hooks bend and people err in their ability to use tools as well.
A steel ruler has a square end that is self supporting on the axle or swingarm and guides itself so to my thinking is going to be closer to foolproof.
To demonstrate my conviction on this to myself I have a Mitutoyo stainless steel ruler 2 metres long.
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Bill Shorten - suspension measurer :)
He will redefine the word "travel", to ensure that the 0.7% of riders with their foot pegs mounted to the swingarm don't feel discriminated against.
"Shorten". Cracks me up.
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If it is of any use as a reference you can download the 2015 AHRMA rulebook here:
http://www.ahrma.org/ahrma_pdfs/Z-2015/Forms/15_Handbook_web.pdf
VMX suspension rules start on page 69 and mentions the rear suspension is fully compressed by the examiner with the rider aboard to compress any rubber bumpers . . . Due to the use of non-standard or different types rubber bumpers, this check may be overridden by the tech inspector’s discretion. . . .Forward-mounted or laydown shock mounts will be closely scrutinized and checked for travel, with three-fourths of the rubber bumper counted as shaft travel.
PVMX suspension tech is on page 80 and appears to be pretty much the same wording other than the allowable travel.
Different bump stops will have different compressed lengths so it seems like you'd want to fully compress them to arrive at the true travel available. Old Girlings etc seem to have pretty hard and incompressable bump stops compared to modern dampers which are designed to give controlled action and are not just there to prevent metal/metal contact at full bump.
I can see how the provision to count 3/4 of the bump stop as available travel could be a reasonable rule of thumb to apply, but it would have to be understood that it may not be as accurate as using the fully-compressed length. But doesn't whatever method is chosen need to be something that can be applied at the track without a major disassembling of bikes/dampers?
HTH,
Michael
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Brad - as mentioned earlier - yes there is a current rule in place re suspension limiters - I am chasing the logic behind it so I can get the full story to work out whether to place a submission to see if feasible to remove it - race our bikes (across a couple of eras) as they came from the factory. No more no less. Instead of being a forum "whinger" (not aimed at any in particular by the way ;D) I was after some info so I can actually do something instead of just talk about it like a lot of guys on here do. It appears there are a few people impacted by the rule across the various bikes.
Simple really - if it goes in so be it, if it doesn't then it doesn't hurt - is that Ok????? Am not bringing it up again for the sake of shite stirring but to find out what bikes are affected.
Some people have a genuine agenda on here? I am surprised you doubted me ;D
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I asked MA how to measure wheel travel a couple of years ago. I'm still waiting for a reply ::)
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I asked about six months ago (just to confirm what I already knew) and got an answer. You just have to ask the right person.
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Is it correct that my standard 74.5 Maico is only eligible for EVO because it is has too much travel for pre-75 and is just not allowed into pre 78?
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Is it correct that my standard 74.5 Maico is only eligible for EVO because it is has too much travel for pre-75 and is just not allowed into pre 78?
Correct. For a sport that is supposed to be representative of the past, that situation is insane.
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.... You just have to ask the right person.
And that's the problem right there.
The rules should be in the book, and should be clearly stated.
We can bitch about forum stirrers all we want, but clear rules will blown every single one of them clear out of the water. Fix the rules and ALL OF THESE ISSUES DISAPPEAR.
Instead, we seem to have secret handshakes, confusion, uncertainty, and inconsistency.
And it's not going to go away until we have some leadership from those with the power.
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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 ?
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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
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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 ?
So you can read and quote from a book. Now tell me the procedure to be used to measure wheel travel.
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Is it correct that my standard 74.5 Maico is only eligible for EVO because it is has too much travel for pre-75 and is just not allowed into pre 78?
Or you could put travel limiting spacers on the shocks and race it in pre 75 like everyone else does both here and in the USA.. It's not hard
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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 :-*
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Sorry Ross but I think the last place to ask a valid question is on this forum! ;)
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your a cynical young fellow Brad, you can find the meaning of life here 8)
see you at CD
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Jeez, five pages of arguing about shock travel?
You blokes need to get out more and just ride the feckin' things.
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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.
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Brad - after 5 pages I find I really cannot argue with you :'( So much for 1/2 glass full eh!
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should have just emailed your local MA commissioner and ask him to clarify, make him work for a living!!lol
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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?
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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.
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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.
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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.
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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.
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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.
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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 ;D
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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
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Sorry, but all this just puts me off getting my YZ250D ready for VMX.
I want to just be able to send my shock to YSS and they rebuild it with new seals and oil and set the travel.
And provide me the parts to fit in my forks.
They provide me a certificate to say what the travel is and engrave something on the shock to indicate that the work was done.
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for the record - MA replied to me yesterday - good quick service. Haven't gone through as yet though - work getting in the way.
Geoff - glad to see you are still a smarta--e!!
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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 ;D
Well put Geoff
This seem like a reasonable solution to me now that the MOMS is online it can be twice (or three) times as big. Of course MA will still have to print some for clubs and level four officials. They will just need a forklift to carry them.
Is there a sarcasm emoticon?
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Sorry, but all this just puts me off getting my YZ250D ready for VMX.
I want to just be able to send my shock to YSS and they rebuild it with new seals and oil and set the travel.
And provide me the parts to fit in my forks.
They provide me a certificate to say what the travel is and engrave something on the shock to indicate that the work was done.
If you send your shock and forks out to be done and asked that they be legal for MA Pre 78 I'm sure they will know what to do.
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This seem like a reasonable solution to me now that the MOMS is online it can be twice (or three) times as big. Of course MA will still have to print some for clubs and level four officials. They will just need forklift to carry them.
The MoMS is back this year to how it was, A5 size (around 210mm tall x 150mm wide). It would appear the "expert" who decided it should only be accessible by downloading it from online, or printed in the massive and impractical A4 format, may have moved on to annoy others...
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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.
Also, changes in rake angle will give a different vertical wheel travel with a telefork even though the swept travel hasn't changed.
Hi Michael,
The rule (in part) doesn't say vertical travel, it says front wheel travel, so it should be as simple as putting a zip tie on the fork leg and giving it a good bounce.
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your'e being too simplistic Glenno ;D,the trainspotters/anoraks will never go for it mate, :P
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More rules means less riders it's very simple maths.
For the people who keep thumping the rule book like a bible just remember when your the last people left turn the lights off when you leave. :'( And yes you will right but you will be very lonely.
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Hi Michael,
The rule (in part) doesn't say vertical travel, it says front wheel travel, so it should be as simple as putting a zip tie on the fork leg and giving it a good bounce.
An easy response to that is "front wheel travel in what direction?" Horizontally, vertically, along the steering axis? If the latter than what about Bultacos that have the forks angled differently from the steering axis?
Teleforks generally get defined by actual telescopic travel. But a telefork at a steeper rake is going to have a larger amount of vertical travel and might be able to absorb a larger bump with it. A telefork with the same stroke on your typical chopper (or raked out Triumph desert sled) won't be able to deal with that bump as well because the wheel movement is more rearwards than vertical.
Rear suspension appears to usually be defined by the rules in various organizations by vertical travel. The actual amount of wheel-path travel for a given vertical dimension on a swing arm suspension will vary with the relative height of the swing arm pivot. A LLF is more like the rear suspension (both use swing arms) than it is a telefork, so it could be sensible to also measure the travel vertically. I presume there is a desire to be consistent and not comparing apples and oranges, but that could be a presumptious assumption.
Shucks, you could even say that teleforks are defined by actual damper travel, so if that is the way the rule is worded any LLF that had less than 7" of travel in the damper should be legal, no matter what the wheel travel might be.
I can put a zip tie on the stanchion of a Greeves LLF and bounce the front end and the zip tie won't move at all. Or I can put it on the damper shaft and say "see, I've got another 3 inches I can add before not being legal".
Words mean things, so you have to be careful how you use them. A rule that depends on poorly defined terms may find itself being challenged with a "what does that actually mean?" question.
If front wheel travel is meant to be measured in a straight line between full bump/full droop axle positions then the rule ought to say that, especially when there are 10-20 years of bikes out there that didn't use teleforks (DOT, Cotton, Greeves, Van Tech, Sachs/DKW/Hercules, Reynolds, some works BSAs and Husqvarnas. Scorpion, Butler, Sprite, Tandon, Royal Enfield, Maico, Tandon, DMW, Cheney, Rickman etc just to name some that I found in reference books with a couple of minutes of page-turning). If the actual distance traveled by the axle (which means along the arc, not the chord, for a swing arm) is what is wanted, the rule should say that.
As I think I said earlier, I think most people are willing to accept a range of rules as long as they sound somewhat reasonable and aren't ambiguous. But at times it can take a bit of thinking to eliminate ambiguity.
My dealings with AHRMA rules leads me to believe that many times the rules are done by people of good will who are fairly expert in the field, but while their expertise may be deep the breadth of their knowledge is just a bit too limited. That can lead to a perfectly sound (but limited scope) rule that fails as soon as someone pipes up with "but what about all of these bikes where that doesn't work?" If they've got zero experience with anything but teleforks, the possibility of making sure that the rule covers leading link/trailing link/girder/who knows what? front ends may never even occur to the rule makers.
I've got/had both Hercules and Greeves LLFs, I've got lots of photos and I can make replicas of Van TechReynolds etc forks and I'd like to run a LLF on some project bikes because I think they are cool and teleforks are kind of dumb. :P So I contacted my local rule makers and asked "how do you want to measure the travel of this fork because the rule book doesn't really apply to it and I don't want to show up and have someone hassle me over "too much travel"." When I can't get an answer it makes me a little uneasy. I'm not looking for any particular answer, but if they can't pick one of three obvious alternatives, what are they doing on a national rules committee?
cheers,
Michael
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There's no suspension limit for vinduro, enduro or trail riding & it's real easy to participate.
K
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Im curious as to why more riders turn up for Vinduro's than even the Nats , can one of you rule thumpers explain that to me?
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Few basic but simple rules & no rulebook pundits/experts. But then vinduro's are non competitive, so there's really no need to disqualify anyone before they hit the track.
K
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So the solution is to run the Vinduro around the MX track, say 10 circuits, put arrows on each corner so we can't get mixed up about which way to go, and to make it easy for the timekeepers start everyone off at the same time, sounds cool n' easy
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Im curious as to why more riders turn up for Vinduro's than even the Nats , can one of you rule thumpers explain that to me?
simple, as it was back in the day minority race, majority ride for fun We've had amazing response to the VinduroWA club over here
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It's funny that the original question wasn't answered. I think asking someone who does suspension would probably get an answer for that. But don't post the question here.
As for how to measure suspension travel front and rear for various different types of suspension the answer I posted on the first page would appear to be correct.
So there is no need for anymore pages.
So can someone lock this post?
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for the record - MA replied to me yesterday - good quick service. Haven't gone through as yet though - work getting in the way.