Set up for the long one.

[Bass]

Eddie's picture at the start of the Gunbarrel Highway has brought an old problem back to mind.
I have often wondered whether we got the suspension set-up right when we did the Oz trip. Specifically, I have wondered, when setting the suspension, whether the luggage should be treated as part of the bike or part of the rider. In other words, should it be on the bike or not, when setting the static sag?
Normally it doesn't matter that much as we don't carry much luggage and we are not going to change the spring to accomodate a tail bag anyway. However, when setting up for a big one, there could be 50 kg of luggage aboard, which has real consequences. Let me illustrate with some simple numbers.
A common rule of thumb when setting the suspension is that the static sag should be about 10% of the total travel and the rider sag around 30%. The difference between these numbers (20%) is the compression forced by the rider weight. If this is the rider only (say 100 kg) then it wil require quite a different spring than if the same travel is rider + luggage (say 150 kg).

So which is it guys and why?
I can think of good reasons for doing it both ways.

[warewolf]

Mounted to the bike = part of the bike, include in static sag.
Carried by rider = part of the rider, include in rider sag.

If it is carried by the rider (ie backpack) then like the rider's weight, it is supported by the "suspension" in the riders legs in addition to the mechanical suspension of the bike. In this scenario it is easier to move the bike around as you aren't moving the luggage too.

Further thought: whether the luggage is on the bike or rider will only affect the preload. In each case the overall load is the same, meaning the same spring.

[Bass]

Mounted to the bike = part of the bike, include in static sag.
Carried by rider = part of the rider, include in rider sag..

This is what i figured as well but is NOT what Robert Taylor did for us. I need to go and talk to that man and see what I can learn.
If you don't include the luggage in the static, with a big load there's a good chance that the bitch won't sit on the side stand when you get off, DAMHIK!




Further thought: whether the luggage is on the bike or rider will only affect the preload. In each case the overall load is the same, meaning the same spring.

You would think so, eh?
Think about the set up procedure though. We set the static and then the rider sags.
Once the static is correct, the only way to adjust if the rider sag is wrong, is to change the spring.
In one of the cases I suggested, the luggage is included in the difference, in the other, it is not. It all comes down to what we include in that 20% compression between static and rider sag.

[Taz]

Surely you can just keep adjusting it til it feels right. I'm sure even with Rob Taylors best guess at your riding style and conditions you may encounter you'd still need to make adjustments to his settings along the way? I would include the luggage in the static.

[Bass]

Surely you can just keep adjusting it til it feels right. .
Well maybe............

I would include the luggage in the static.

This is the key and why I asked the question.
If the luggage is part of the static load, then the required spring rate depends only on the rider's weight, meaning preload adjustment is all that is necessary and yet Robert fitted us with stiffer springs.
If the luggage is part of the rider weight (and for a long trip, it could be as much as 50% of the total rider + luggage weight) then a spring change will almost certainly be necessary.
So Colin's, your's and my instincts are at odds with what Robert did and so far I can't figure out why.

This is all based on my assumption that we should have about 10% static sag and 30% rider + static sag under all conditions, but I'm no expert. That could be complete bullshit.
It also feels wrong to say (as I am doing) that regardless of how much luggage I put on, I don't need to slot in a stiffer spring because the luggage is part of the bike, not part of the rider. So obviously, there is something that I haven't got my head around yet.

[Taz]

You might find it impossible to get the correct static sag within the original springs adjustment range when the bike is weighed down with luggage. Therefore to bring the sag into spec may require a change in spring rate. Remenber there is a finite amount of range when winding the spring down. Sure you may have some thread left on the body of the shock but that does'nt mean you can use it all.

[That looks like fun]

KISS A simple philosophy that works. I have seen people mess around with suspension and steering, tyre pressures and all sorts of things when at the end of the day they have a riding style or load that is completely outside the parameters of what they have set up. Ask a simple question before you start changing things "is this bike designed for this" Chances are not many bikes are made to be loaded to the rafters with panniers so wide they need a pilot vehicle and then ridden up a vertical hill with overweight riders and pillions simultaneously shitting on the seat. I don't claim to be the worlds best rider (not even second best), I adjust the suspension so that the I feel like I have control of the bike, not the other way round. Saves on carrying around a set of scales, some cable ties and a calculator in every pocket

[Bass]

simultaneously shitting on the seat.
Could get messy!!!!
Don't mistake my intent here - I am pretty satisfied with the way I have it set up.
However, I have an interest in the theory and am trying to fill some gaps in my knowledge.

[Bass]

You might find it impossible to get the correct static sag within the original springs adjustment range when the bike is weighed down with luggage. Therefore to bring the sag into spec may require a change in spring rate. Remenber there is a finite amount of range when winding the spring down. Sure you may have some thread left on the body of the shock but that does'nt mean you can use it all.

That's possible but unlikely.
Your luggage is unlikely to weigh more than a pillion passenger and the manufacturers usually give enough adjustment to allow correction for the weight of a pillion.

[dino3310]

Could get messy!!!!
am trying to fill some gaps in my knowledge.
i use beer for that

[warewolf]

You would think so, eh?
Think about the set up procedure though. We set the static and then the rider sags.
Once the static is correct, the only way to adjust if the rider sag is wrong, is to change the spring.
In one of the cases I suggested, the luggage is included in the difference, in the other, it is not. It all comes down to what we include in that 20% compression between static and rider sag.What I am saying is that once you have the correct spring, moving the luggage from bike to rider or vice versa means only a preload change. Essentially the spring must support all the weight - bike, rider, luggage - at the correct rider sag, but the preload says "how far through the stroke are we positioning the dead-weight of the bike (ie everything below the rider's legs)?" which is static sag.

Edit: because the luggage should always be factored in, if you are setting up for a big trip with big luggage.

[Bass]

Colin, I do understand where you are coming from. You and I really are going to have to organise a discussion over a beer at some stage. Some of the info you have posted in the past has been invaluable, especially the numerical descrition of linkage performance.
In this case, your point of view (and I cannot say that you are wrong) begs the question that if the total load does not change (and it doesn't in shifting the load from the bike to the rider), then why is any adjustment at all necessary? After all, the spring is carrying the same load regardless of where it is attached.

[NordieBoy]

Colin, I do understand where you are coming from. You and I really are going to have to organise a discussion over a beer at some stage.

I'll referee.


Typing out loud here...


Hmmm...


Static sag...
So the suspension can extend into dips/holes without topping out.

Rider sag...
So there's enough suspension travel left to prevent bottoming out all the time.

Sooo....

The spring rate needs to be set for the race sag (rider + luggage). At this point the static sag is just academic.
Damping also needs to be set for the total weight.

So it doesn't really matter if the luggage is attached to the bike or the rider.
The difference is that the luggage attached to the rider is higher (bad) but moves with the rider (good) but fcuks the riders back (bad)..
When attached to the bike it's static over the back end (bad) but low (good) but can fcuk the bikes back (bad).

Therefore: Spring rate and damping for total weight carried and reinforced backs.

I need a milo.

[junkmanjoe]

after having a read in here, i went out and wound my shock up a little...

JMJ & 9FIDY

[dino3310]

after having a read in here, i went out and wound my shock up a little...

JMJ & 9FIDY

i went and got a panadol

[cooneyr]

Sounds good to me Nordie. Springs and damping being set up for total race weight weight. This would mean that the static sag is probably just a good way of figuring out if the springs are right or not.

[warewolf]

why is any adjustment at all necessary? After all, the spring is carrying the same load regardless of where it is attached.= rider sag, or sag "all in". Wot I bin sayn all along. :D

The adjustment comes because the amount of the load sprung by the rider's legs changes. Dunno exactly why, that's just how "they" set bikes up. Suspect it is because while standing up (it's more obvious) the torso doesn't move as much as the bike; the legs flex between the load & the chassis in the same way the bike's suspension flexes between the chassis & wheels.

Mmmm, beer!

[junkmanjoe]

is width a factor to the mathematical combination of numbers...

JMJ & 9FIDY

[NordieBoy]

is width a factor to the mathematical combination of numbers...

Only if you're counting wind resistance.

However if the tops of the containers slope forward then at speed there'll be some wind induced loading of the suspension as well.

[junkmanjoe]

so they will act like a wind spoiler to help hold the rear wheel on the ground with down force...when i reach maximum velocity...

[Waihou Thumper]

i went and got a panadol

Haha, that is funny...lol Just ride......:)

[Waihou Thumper]

is width a factor to the mathematical combination of numbers...

JMJ & 9FIDY

NO, just have enough money to pay for the Wide load Pilot vehicle...:)

[Bass]

The spring rate needs to be set for the race sag (rider + luggage). At this point the static sag is just academic.
Damping also needs to be set for the total weight.

.

At last, despite the clowns, an answer that makes sense.
So, what this means is that the luggage is NOT part of the static sag.
Thanks Fran.
This gives me a means of quickly and exactly calculating the correct spring rate for the next big trip.
"Just riding it" isn't an option. Believe me, after 20,000 km and 85 million corrugations, half of which you can camp behind to shelter from the wind, if it ain't right, your arse is grass. The likelihood of a serious breakage goes up dramatically too.
As an aside, I ran into Ken MacIntosh at Motomail a while ago and had a really interesting discussion. He uses a drill press and a set of bathroom scales to measure spring rate - so simple and ingenious.

[warewolf]

so they will act like a wind spoiler to help hold the rear wheel on the ground with down force...when i reach maximum velocity...That will act like a lever on the rear of the bike, lifting the front causing understeer. Not what you want at max velocity.

[NordieBoy]

That will act like a lever on the rear of the bike, lifting the front causing understeer. Not what you want at max velocity.

Only if the centre of the top of the box (centre of effort) is behind the rear axle :D

[NordieBoy]

At last, despite the clowns, an answer that makes sense.
So, what this means is that the luggage is NOT part of the static sag.
Thanks Fran.
This gives me a means of quickly and exactly calculating the correct spring rate for the next big trip.

As long as you always ride with the extra weight.

[Bass]

As long as you always ride with the extra weight.
This whole thread was about setting up for the big one - so that's a given.
The DR has the stock spring on the back these days

[That looks like fun]

Just went out to the garage and poked both shocks (front and the other end) with a stick and niether of them sagged and I never got a static shock :yes: so the sprung vs unsprung wieght must be in balance with the power output of x squared by the root of the tree in the middle of the field 2 men plowed on a moonlight night.:shifty:
I think :blink:

[Bass]

so the sprung vs unsprung wieght must be in balance with the power output of x squared by the root of the tree in the middle of the field 2 men plowed on a moonlight night.:shifty:
I think :blink:

Times 3 foot 6, minus a bottle of orange

[tri boy]

Neil, remember that even the best suspension guru's like Robert or Paul Thede (Race Tech founder) acknowledge that their job is to set suspension up with "the least amount of compromise".
But their is always compromise. Don't fall into the trap of over thinking what the forks/shock are doing in an attempt to nullify every type of load factor.
What may be 95% tuned for ruts, will have you cursing as you go into soft sand etc
Just my opinion.

[tri boy]

Neil, remember that even the best suspension guru's like Robert or Paul Thede (Race Tech founder) acknowledge that their job is to set suspension up with "the least amount of compromise".
But their is always compromise. Don't fall into the trap of over thinking what the forks/shock are doing in an attempt to nullify every type of load factor.
What may be 95% tuned for ruts, will have you cursing as you go into soft sand etc
Just my opinion.

[NordieBoy]

Just went out to the garage and poked both shocks (front and the other end) with a stick and niether of them sagged and I never got a static shock :yes: so the sprung vs unsprung wieght must be in balance with the power output of x squared by the root of the tree in the middle of the field 2 men plowed on a moonlight night.:shifty:
I think :blink:

What's the wind direction?

[Bass]

Neil, remember that even the best suspension guru's like Robert or Paul Thede (Race Tech founder) acknowledge that their job is to set suspension up with "the least amount of compromise".
But their is always compromise. Don't fall into the trap of over thinking what the forks/shock are doing in an attempt to nullify every type of load factor.
What may be 95% tuned for ruts, will have you cursing as you go into soft sand etc
Just my opinion.
I agree completely.
I'm just trying to get a feel for the rules to get to the starting point. I fully understand that the tuning starts in earnest from there.
There are some widely used rules of thumb, one of which I have mentioned repeatedly. I've simply been trying to figure out how to apply it in a particular case. Fran set me straight and at the same time explained why R.T. set it up the way he did.
However, if you read back, you will see that the question that I asked was very simple. "If we carry a heap of luggage, should we treat it as static or dynamic loading?"
Most of the respondents, me included, got it wrong.
Brent, there was no question of over-thinking it - we are dealing with the absolute basics here. The most basic suspension adjustment we have is changing the spring rate. Get that badly wrong and there is nothing else we can do that will compensate for it.

[Phreaky Phil]

Here's my 10cents worth. I ride with a pillion nearly all the time and quite often luggage. I have a stiffer spring so i can get the static sag somewhere in the picture with the bike loaded then the race sag is in the ballpark with rider and pillion. Without the stiffer spring winding preload in doesnt accomplish much. Even with the ride height set up right it still unweights the front end. No problem with traction tho. IMO the only time you would treat the luggage as race sag is if you were carrying it on your back

[Phreaky Phil]

What rear shock do you have ? modified stock or Ohlins ?

[tri boy]

I'd treat the extra weight as static.
Own a couple of springs, and change them to suit load conditions. ie, full blown Aussie trip, and change back to the lighter spring for NZ weekend adv rides. MHO

[Bass]

Guys, if you are fitting stiffer springs to carry the extra load, then you are treating it as part of the rider load, not the static and it's by definition.
Question - how is a pillion passenger different from a big load of luggage? (Don't tell the wife I said that.) I can understand what Colin said earlier that putting the load on the rider's back instead of the bike, needs adjusting for as the rider's legs can be part suspension. However, the pillion doesn't get up on the pegs or move around much, if at all.

So how is the pillion load different to a heap of luggage?

Consider what we do to set the bike up.
Imagine a completely bare bike. The first thing we do is set the static sag by adjusting the preload - typically so that the sag is about 10% of total travel.
We then add the rider and if the spring is rated properly, the total sag will be about 30% of total travel, i.e. the rider adds 20% more sag.

Now put some baggage on and repeat the process.

Adding the baggage will have increased the static sag, so we increase the preload to bring it back to 10%.
Add the rider whose weight hasn't changed and the total sag will again be 30% (Hooke's Law) The rider will always increase the sag by 20% for this spring.

Add more baggage and repeat.

You get more preload but no reason to change the spring and it will stay that way so long as the extra load is treated as static. The extra preload is carrying the baggage and you still get your 10%/30% measurements.

Now look at it the other way.

Set the bike up completely bare as before i.e. 10 static and 30 with the rider aboard.

Now add the rider and baggage as well and where it is mounted doesn't matter. The static sag hasn't changed but the rider/luggage sag will now have increased alarmingly. The static sag is still correct. Take the rider/luggage off and check it. We don't need to change the preload then.

The only way to get the rider sag back to where you want it is to fit a stiffer spring i.e. to treat the luggage as rider load.

My Triumph is set up this way as it gets most use 2 up. It has an aftermarket shock and more importantly a stiffer spring. Putting an extra 65 kg or so in the panniers has exactly the same effect as putting Nicky on the pillion seat.

[That looks like fun]

Just read all that and now my brain hurts.:sick:
Wind is from the South East Quadrent Nordie,:shifty: where did I leave me orange juice, :blink: Im off to lie down :bye:

[Phreaky Phil]

Depending on the weight of the luggage you will get to a point with the standard spring where no matter how much preload (and there is a maximum) you give it you cant get the static sag set right or if you do then the rider sag is wrong. With a lighter spring your compression damping will have to be increased to compensate for the increased load . Increasing preload doesnt make the spring stiffer, just alters the force required to initially compress it. A heavily preloaded spring may mean the shock is harsh in its initial travel.
At the end of the day I think which ever way you look at it you need a heavier spring and ya have to shag around with settings till it works best for you. Ive read some interesting debates online about suspension and without trying all the options its hard to say that something wont work better
I'm happy with the spring weights on mine GS but its not good on the gravel corrugations. In talking to Robert and Dennis at CKT the shock has to much high speed rebound and packs down over the corrugations.
In Alaska I had an Ohlins in my Dakar with a stiffer spring. Kelvin had a stock shock and even with his preload at max mine rode 50mm higher in the rear. We both hit a set of frost heaves and the impact in his sheared a subframe bolt off.

[tri boy]

Just buy another spring already:yes:

[Bass]

Depending on the weight of the luggage .................................................. .......................shock and even with his preload at max mine rode 50mm higher in the rear. We both hit a set of frost heaves and the impact in his sheared a subframe bolt off.

Phil,
To answer an earlier question, I have Ohlins front and rear.
Secondly, I don't disagree with a thing you say, but I didn't want to bring damping rates into this discussion as it is complicated enough already.
Lastly, both you and Brent are saying that you would treat a big luggage load as a static one but in the same breath are saying that you have heavier springs to cope with exactly that situation.
I was simply pointing out that in doing so you are contradicting yourselves. If you are stiffening the spring to cope with the load then by definition you are treating it as a non static one. I was also (obviously unsuccessfully) trying to explain why this is so.

I know I sound pedantic, but by understanding that the load is NOT a static one, I can now add any size luggage load to my bike that I want and by taking a few simple measurements using the existing spring, I am able to calculate the spring rate of the new one that I need.
As I said earlier Nordie gave me the key and I have the answer that I wanted.

[Phreaky Phil]

I think you have to look at the springs and damping together. From a different perspective, there are two basic types of road condition that affect the suspension. First, a bump in the road. The rear wheel is forced upward. the extra weight on board is not affected by this. The spring and comp damping limit the upward movement and the rebound controls its decent.
Second. Dips or holes in the road. The wheel and whole rear of the bike drops into the hole or dip. With the greater mass the spring and damping have to control the compression. The more mass on the back, the faster compression. Wind up the preload, once the spring is compessing it has no effect. only stronger High speed compression damping will help. This wont be good on the first type of bump. With a heavier spring, it has more resistance to the comprerssion and the high speed compression damping can be lighter.
I'm not sure that will make any sense, buts its interesting trying to put thoughts from your head into text !!:confused:

[That looks like fun]

Ok, you win I will show that I can be serryus. :shifty: Forget sag, rebound, static and all that stuff. :mellow: Lets look at "Sprung" vs "Unsprung" weight. :yes: Any weight not supported by the springs, eg wheels, tyres, etc can be taken straight out of the equation as we have little control over that (unless you mount your load to the axles somehow, but why? :blink:) Everything else is "Sprung weight" Regardless of if the weight is carried high, low, forward, back or by those poor buggers plowing the field. If it is supported by the springs it becomes part of the sprung weight.:mellow: AND THE SPRINGS HAVE TO BE STRONG ENOUGH TO SUPPORT SAID SPRUNG WEIGHT while maintaining the ride height characteristics of the vehicle. This is so the suspension has the correct amount of travel to go up and down goodo :yes: So now that we have the load carried and supported properly shall we look at the real problem.............
Yes the vehicles damping devices (thats shock absorbers to ewes), righto, away ya go sort them out :shifty:

[warewolf]

Okay, there's a bit of misquoting/misinterpreting throughout this thread :) I'll try to be clearer. :D


This is the key and why I asked the question.
If the luggage is part of the static load, then the required spring rate depends only on the rider's weight, meaning preload adjustment is all that is necessary and yet Robert fitted us with stiffer springs.
If the luggage is part of the rider weight (and for a long trip, it could be as much as 50% of the total rider + luggage weight) then a spring change will almost certainly be necessary.
So Colin's, your's and my instincts are at odds with what Robert did and so far I can't figure out why.No, actually I'm with Robert all the way on this, and that's what I was trying to say... which is what Nordie said clearly. Also, the required spring rate never depends only on the rider's weight; I think you wrote to the contrary a couple of times - not sure if I'm misinterpreting why.

I agree mostly with what Nordie wrote. The critical difference: static sag matters; it matters because it tells you if the spring is correct. To achieve the correct rider sag (bike/rider/luggage total load irrespective of mounting point) you could have one of these three options:


too light spring too heavily preloaded
correct spring & preload
too heavy spring too lightly preloaded

Once you have the rider sag set, checking the static sag tells you which of those three scenarios (springs) you have. At this point, choosing whether to include the luggage in the static sag is utterly critical to your analysis. (And without the luggage mounting options, static sag is still critical - it is no more or less academic than the whole rest of the exercise.) With the luggage firmly mounted to the bike, the luggage only uses the bike's spring so you need more spring there. Mounted to the rider, the luggage also uses the rider's leg springs, so the bike's spring can be lighter.

But we are only talking about theoretical ideals: it is only the starting point. Tune from there as you see fit.

[warewolf]

Lastly, both you and Brent are saying that you would treat a big luggage load as a static one but in the same breath are saying that you have heavier springs to cope with exactly that situation.
I was simply pointing out that in doing so you are contradicting yourselves. If you are stiffening the spring to cope with the load then by definition you are treating it as a non static one. I was also (obviously unsuccessfully) trying to explain why this is so.
I don't think they are contradicting themselves. But I don't yet understand your explanations - yet we might be saying the same thing in different words :lol: Will think about it some more tomorrow. At this stage I am thinking that the two sag measurements interact to give you the answer, and that changing the load doesn't influence one without the other; it is their relationship that is important.

Easy:
Static sag = bike
rider sag = bike + rider

Hard:
Static sag = bike + luggage
rider sag= bike + luggage + rider
OR
static sag = bike
rider sag = bike + luggage + rider

In either of the "hard" cases, luggage being moved in/out of static sag changes both configurations as the ratio & relationship between the two sags changes. Note: you cannot simply use rudimentary algebra to cross off each occurrence of luggage in the first "hard" case to make it resolve to the easy case... Rider & static sag occur at different positions in the shock's rising rate, for starters... and that's just the first curvilinear example that popped in to my head.

I think your examples re: the Trumpy & pillion don't compute, because although you invoke Hooke's law (correct, as far as a linear load on a spring goes) you omit the rising rate suspension. The rider will not always increase the sag (sag = travel measured after linkage applied) by 20% for that spring. Yes the rider will always increase the load and thus compression on the straight-rate spring by a consistent amount; no that does not translate to an equal linear change in travel through the linkage to your sag. Admittedly the curve is fairly slight at that part of the travel, but it isn't flat.

Make sense?

With each 1 turn (1.75mm) change of preload to the rear spring of the 640A, I don't get a consistent (linear) change in static sag. Between 8 & 15T it yields 3.5-5.3mm of static sag change per T, and 0.4-6.0mm of rider sag per T. No weights changed, just preload consistently and the output varied by the rising rate. Try it on your bike.

[Bass]

I think you have to look at the springs and damping together.
:


Eventually, of course you do and I guess that everybody learns in their own way.
My way is to try and understand the influence of each component separately before trying to figure out their combined effect.
If you want to discuss damping, I am happy to, eager even. However as you have pointed out, it can be difficult getting across our exact meaning when conversing like this.

[Bass]

Ok, you win I will show that I can be serryus. :shifty: Forget sag, rebound, static and all that stuff. :mellow: Lets look at "Sprung" vs "Unsprung" weight. :yes: Any weight not supported by the springs, eg wheels, tyres, etc can be taken straight out of the equation as we have little control over that (unless you mount your load to the axles somehow, but why? :blink:) Everything else is "Sprung weight" Regardless of if the weight is carried high, low, forward, back or by those poor buggers plowing the field. If it is supported by the springs it becomes part of the sprung weight.:mellow: AND THE SPRINGS HAVE TO BE STRONG ENOUGH TO SUPPORT SAID SPRUNG WEIGHT while maintaining the ride height characteristics of the vehicle. This is so the suspension has the correct amount of travel to go up and down goodo :yes: So now that we have the load carried and supported properly shall we look at the real problem.............
Yes the vehicles damping devices (thats shock absorbers to ewes), righto, away ya go sort them out :shifty:

I don't understand your need to ridicule, especially as in this case I think that you are pretty much correct. What you are effectively saying is that there is no such thing as static loading - it's all dynamic and that any change to the weight carried by the suspension IDEALLY requires a change in the spring rate.
I agree with you
It's just a bitch that it's impractical to be changing springs every 5 minutes.

If you want to talk damping, fine.

You start. How's your differential calculus?

[Bass]

Okay, there's a bit of misquoting/misinterpreting throughout this thread :) I'll try to be clearer. :D



No, I'm obviously the one who needs to be clearer as so far I have made a piss poor job of explaining myself.

I was trying to point out the logical consequences of considering the luggage as part of the static load. The main one is that the spring rate then becomes dependant on the rider weight only. This is obviously nonsense and so the luggage cannot be part of the static load..
I apologise for not spelling that out.

I agree with the rest of your analysis except that I would set the static sag first, but that's a personal thing. I guess that in effect you are saying that the spring rate depends on the difference between static and rider sag. I agree completely.
I now think that the static sag MUST be set without the luggage however which is what I was asking at the outset.

Despite appearances to the contrary, this thread has been of significant assistance to me as I now have the means to pack a bag for the next OZ trip (whenever that may be), chuck it on the bike, take a few measurements and order exactly the spring(s) that I would need. I need to know the existing spring rate of course, but I can measure that.

So far as the Trumpy goes, I was trying to illustrate that while most of the respondents here were differentiating between rider(s) and luggage, so far as a pillion was concerned that there was no difference in their effect. I could either put my 65kg wife on the pillion seat or I could put 65 kg in the panniers - the effect on the ride would be the same for both - again trying to push the point that the luggage is not a static load.
I have actually been trying to keep rising rate linkages out of this discussion because of the added complication and because it's not actually necessary to consider them provided we are always making comparasons at the same points of the suspension travel.

[That looks like fun]

I don't understand your need to ridicule, especially as in this case I think that you are pretty much correct. What you are effectively saying is that there is no such thing as static loading - it's all dynamic and that any change to the weight carried by the suspension IDEALLY requires a change in the spring rate.
I agree with you
It's just a bitch that it's impractical to be changing springs every 5 minutes.

If you want to talk damping, fine.

You start. How's your differential calculus?

Its not an overwhelming need to ridicule:shifty: In fact some see it as humour. However in a two dimensional world such as print the writers intent is open to interpretation by the reader :yes:
As a mechanic (in a life before I found trucks) I met many people who with best intent over complicated things for little gain. IT repair people are classics at this, just ask them to build you a simple program based on excel and see what you get :blink:
Colin actually gave the best answer I have seen so far when he explained how to know if you have the correct "springs" for the load being carried. Static, Dynamic, don't matter. If the spring is required to carry that weight then it needs to be designed and set for it. Once that is done your ride characteristic's are controlled by the shock absorber and the vehicles design limitations.
Changing where the load is carried (on rider or on bike) will have an effect on required shock absorber action :mellow:

Differential calculus,:shit: I think thats the piece on the back of the truck that distributes the torque of the engine equally at right angles to the prop shaft what makes the wheels go round and round :yes:

[Bass]

Its not an overwhelming need to ridicule:shifty: In fact some see it as humour. However in a two dimensional world such as print the writers intent is open to interpretation by the reader :yes:


There is an old saying although no-one seems to know who first said it......................"Sarcasm is the lowest form of wit"


Differential calculus,:shit: I think thats the piece on the back of the truck that distributes the torque of the engine equally at right angles to the prop shaft what makes the wheels go round and round :yes:

Let's get this straight. I was annoyed/surprised at the tone of your posts, especially because in the finish, you had some really valuable input into the discussion.
I hear where you are coming from and I completely agree with the kiss principle. I think your approach is great for making the best of what you have. However, I want/need to go further than that and to do so I have to be able to understand what is going on at a fundamental level, especially if in due course I am able to specify my own equipment.
Let me gve you some background and perhaps you will see where I am coming from.
Two years ago, a friend and I prepared a couple of DR's and spent 2 months doing back-block Australia. Part of the preparation process was spending significant sums of money with Robert Taylor. What we received for our money initially appeared to work really well and we were pretty happy. However, once we got to Oz we were less so. Firstly, it quickly became apparent that the forks on the two bikes were set up differently and we couldn't understand why, since they were done at the same time and we are almost identical in weight. We have never resolved that.
Eventually we got the back ends pretty well optimised and remember that we had buckets of time to experiment.
It was corrugations that were the problem and initially we got our arses hammered. After a while we got things to the point where we could tackle small to medium corrugations at speed. However, if we suddenly ran into deeper corrugations (which was so common as to be normal) we got hammered so badly that it felt like our eyeballs were coming loose and we like literally could not see.
Now I have to be fair here and say that we covered 18,000 km in 2 months and we had NO breakages. In fact the DR's were models of reliability and so Robert must have got something right. Back in NZ I have put the standard spring back on the rear shock, but have left the stiffer springs in the forks beause the DR is notorious for being soft in the front and we have left the big tanks on. I have to say that it think it goes pretty well for an old DR, but the compression damping on the rear is still too high and it's set for minimum. It probably needs a thinner bottom/main shim.
However, I have always wondered if it was possible to get them to perform better than they did and I am determined to get myself to a position where I am capable of doing that evaluation myself. I am not just talking a "shit, this goes well" qualitative evaluation either. I want the numbers.
If at the end I am forced to the conclusion of "that's as good as it gets for a DR" then so be it.
If however I can find a way to put the load that we were carrying back on and get the beast to do it right, I will go and have a word with Robert. I have no intention of kicking his arse, I am just happy to spread the information around. I also want to be at an appropriate level technically so that I can have that discussion without making a dick of myself. That's where the differential calculus comes in and many years ago I could have written the equations that describe the movements in question. It WAS many years ago sadly.

[warewolf]

This is all good! :D

I don't think it really matters whether you set the static or rider sag first. I've read set-up guides from various suspension experts and they aren't consistent, although rather more do say start with static. That's possibly because it can be done solo. The order you set them doesn't change the result in the other.

Pillions, hmmm well I think they should contribute to the static load, but not 100% since they too have legs. My wife moves with me, and I can telegraph my intentions. If I start to take my weight on my legs, she does too.

[That looks like fun]

My point was, is, was and shall remain that the ride of the bike is controlled by the action of the shock absorbers. The springs (at their basest level) merely support the sprung weight of the bike (or any vehicle for that matter) in a position that allows the shock absorbers to perform to their optimum. Get the right springs for the weight, set the shocks for the terrain to be covered plus matched to "your" riding style and presto, perfection. Change any of those things and Viola it all turns to custard.
Remembering that we do not ride on a race track (where the conditions alter very little from lap to lap) so much of what we do is compromise. :yes: Sand, corrugations, compacted gravel, freshly graded gravel, and thats all in the first ten meters of leaving home :shit:
However its good to experiment and trial new theory's and ideas, after all thats where progress is born. The KISS system reminds us that sometimes you just got to realize that you cant make a silk purse from a sows ear. :shutup:

As for Sarcasm, it may be the lowest form of wit but they make good coffee :yes:

[Phreaky Phil]

The reason I asked what shock you were using was, I used to have a DR650 :shit:. I spent considerable time and effort on the suspension. It was set up with Ohlins rear. 0.43 front springs with Race Tech Emulators. I even experimented with different triple clamps as I never really like the way it steered on gravel. When I refitted the stock shock to sell the bike I couldnt believe how bad it was.
The best suspension on a bike ive owned was my WR400 with Ohlins rear and somebody's fork kit. The Ohlins rear made a HUGE difference, even 2 up on gravel, it soaked up everything. Plush like a plush thing !! I dont know why it was so good. Maybe the valving was spot on. Maybe the leverage ratio's were better than others.
I think the corrugations are probably one of the hardest things to set up for. Its a lot to ask of the suspension, to pound up and down about 10 times a second, and in Australia to do it for hours at a time !!
As I mentioned earlier my Beemer shock is packing down over corrugations. You can feel the rear end sit down and stiffen up and you loose forward drive or it steps out sideways.
A revalve is the only way to cure it and may take several goes to get it right

[That looks like fun]

Beemer shocks (standard ones) are notorious for not handling repeated work, eg corrugations. It is a lot to ask of a mechanical device that is supposed to stop (at a controlled rate) the actions of a fully laden scooter when all of the forces that Sir Isaac could think of are trying to throw it into orbit at the top of the bump then send it to china at the bottom, then allow the suspension to return to its correct position ready for its next beating.
Lets not forget the other factors involved, say... rider style for instance. Once you have the bike set to the optimum compromise for the surface you are expecting to ride on, the easiest adjustment you can make on the road is to the rider.:blink:
As an example, I was carrying out an assessment of a job applicant part of which involved a practical driving assessment. On a particular corner I know well he tucked the front of the unit off into the water table and went round the corner goodo :yes: I knew why he had done it but asked anyway. Sure enough his reply was that as the corner had a slight off camber and double apex, by using the camber of the water table to essentially hold the truck to the left he avoided the weight of the truck carrying it over the centre line on the exit to the corner. :yes:
I asked him if he knew of another way to solve the same problem, after a blank look and a long silence I gave him a clue, go into the corner a bit slower :shifty: He laughed and said fair call :yes:
Got the job :yes:

[Phreaky Phil]

Ah Grasshopper !! Mine not standard BMW shock. It was built below sea level:confused:

[Bass]

Ah Grasshopper !! Mine not standard BMW shock. It was built below sea level:confused:

Workshop in the leg of an offshore rig?

Ship's engine room?

[warewolf]

Behind a dyke in the Netherlands... WP? Or does that yankee mob (Works Performance?) have their factory in Death Valley??

[Phreaky Phil]

Right on the first try.:clap: Dutch made WP. I believe they're now Austrian made WP
Behind a dyke in the Netherlands... WP? Or does that yankee mob (Works Performance?) have their factory in Death Valley??

[warewolf]

Yep: WP Suspension Company About Us (http://wp.nl/company/about_us.php)