I’m running a R1100GS attached to an Ural chair with Claude’s swaybar and the Leverite kit to reduce the trail. It is time now to upgrade to aftermarket shocks. The stock shocks after 36 K miles are very tired and the bike is so low. I will go with the Wilbers suspensions and they are custom built to your specifications, weight, height, riding style, etc. Well all these information are of course for bike on 2 wheels, but for a rig where the weight of the chair already compresses the bike suspensions and in the turns the lateral forces apply to the shocks, it should be quite different. How can we calculate the total load on the bike to get the right shock, weight of the rider + X %! These shocks can also offer special lowering or raising kits, if I raise the riding height by 1”, (I’m 6’6”), how will handle the rig versus the standard height or even a lower one.
I know that the setup of the suspensions could make a huge difference in the rig’s handling. Any comments or suggestions would be appreciated, and hopeffuly see you all next week in PA for the RDV rally.
Thanks, Didier
I have been, having the same rig combo, asking that question myself... over and over including some conversations at RDV III... and it seems... to my desapointment, as in my book, suspension is a primordial aspect of a bike or rig... NO ONE KNOWS...
Would this be an area that is obscure to all... or has no one ever gave it any consideration? even Hal Kendall?
Here is the scenario... 200lb rider + 100lb of gear... solo the spring rate should be around 250lbs to allow a rideable solution for also no gear situation... right?
Now, we are adding a car... total weight with subframe, lets say 300lbs... there is what I call a tongue weight induced by the two lower car mounts to the bike... right? What would be that tongue weight? The sure way I imagine to find that out would be to detach the car and set the lower mounts on a scale at the same angle the car is mounted to the bike and... weight it... correct? Is it half?... of the car weight? 3/4?
Do we need to take in consideration the incredible lateral forces in twisties to the bike's suspension? Should that number be added to the bike's spring rate?... and end up with a spring rate of around 350 to 400lbs?... and then again... what should the spring rate of the chair be???
Anyone?... and please... don't tell me that I worry too much... and to just ride it... I am embarking myself and Spirit May 1st 2007 on an indefinite journey and it would be nice to be "properly supsended"... 🙂
Be well... Ara
I think this is one of those "How much is too much" questions. If you send ten identically sized people to the Sleep Number Store and ask each to lie down and adjust the bed for a perfect comfort, you'll end up with ten different numbers. Or ask ten people to tell you how much money is enough to live on. :0)
As far as weighing the "Tongue weight", I'm guessing you already know how much your bike weighs. If so, load the bike down as you would for a trip and take the rig to a feed mill or truck stop with a scale. Instead of weighing the entire rig, pull on so that only the bikes tires are on it and the sidecar tire is on the framework. That should give you the added weight the sidecar puts on your frame.
OK... now that is smart and I had not thought about it! There is actually one down the road and will try that and see what we come up with...
Keep sending the replies... rig engineers...
Be well... Ara
Guess I may as well jump into this one. (And everyone said "ugh")
The reason that you cannot get a direct final answer is that there is not one. Spring rates, shock valving , the addition of a swaybar etc are all subjective to the feel of the rider to a certain degree.
If I SAID ''" Go with a 400 pound spring" what was actually said? Would you be satisfied with that answer? The answer maybe ... but in application who knows? Not me. You may want a progresively wound spring so the spring rate increases as it gets loaded more.(GOOD IDEA!) This should be discussed with the shock supplier. If you are to keep the swaybar in place on the street you can run sofer springs than with out one. How much? Still a subjective answer is all that can be offered.
These GS based rigs sit high off the ground and have a long travel suspension allegedly for off road use. This is not a bad thing but the stance of the rig itself limits it's cornering prowness on hard surfaces. THINK ABOUT IT...We see monster trucks that are so high you can walk under them and they do what they do well but you will never see a formula one car with much ground clearlance at all. These are purpose built vehicles and do very well for their intended purpose.
Now we get to the street and we have to compromise what is the ultimate designs to make a vehicle work under many varied conditions.Making a rig work under varied conditions is actually harder than making one work when the surfaces they are running on are consistanly about the same.
You both have reported here the difference the addition of a simple anti swaybar made. The swaybar allowed the rigs to work pretty well even with the softer suspension. I did not run your rig very hard Ara but did push Didiers a little when we went over the mountain. It worked quite well actually. Before the swaybar addition it really falt out of it's element in the twisties...and you know what I mean.
Spring rate and ride height are two different subjects even thoiugh one may affect the other. This needs to be discused with the shock suppliers. Do you really want to up the spring rate or just add ride height to the rig? It may be a good idea to see what your present spring rate actually is. If you can find a local racer (There are a lot of Stock Car racers in Georgia and Modified guys in N.J. to seek out) they may have a spring checker (should have). See if they will check your springs for yOU. Yopu could probably even do it on a feed scale to establish some kind of reference point even if it was not that accurate. Before taking the spring off the bike measure the length of it. Then when it is checked you can check it at that length. It will get longer (maybe..lol) when removed from the bike's shock.
There is a lot of 'hit and miss' on a topic like this. I could say ..
"Okay go with 400 pounds" and you would maybe say : " Great , finally someoen gave me a straight answer"....BUT...I could not be honest if I said it was the right answer as there are too many varibles involved. One of the big variables is your feel when riding. That is why It may be good to check what you have now to establish a base line to go from. I don;t care what the shock manufacturer said the spring rate was when you bought the shock you have. The question is what is it now! Also if you want to split hairs check the spring rate on your new shock when you get it to have a real life reference point then go from there with it. It is almost a given that the spring rate between shockS will vary even when new. It is also a given that these spring rates will change slightly after usage some more than others.
We can play the nuMbers gaMe forever and talk on thsi type of subject but if we really want to get technical the springs have to be checked at various times and at various compressions and recorded.
What did all of the do for us in the real world? Nothing, if my rigs blows yours off in a right hander or visa versa.
We can get really wrapped up in a monkey see monkey do world. Racers are notorious for this until some monkey tries somet
First i will start by saying - i agree with Claude... if the suspension is too soft for your liking - stiffen it... if it is too stiff - soften it. As for the BMW shocks - when you call Klaus - the Wilbers distributor in NJ - he will be able to give you the original specifications from when your bike was new. At this point - having seen your bike and the way the suspension wallows - you can assume you are no where near what the stock settings were. Do you need to measure the functionality of the shock now? I can appreciate the science involved - but that seems like a waste of time. Start with the stock settings from BMW - and calculate the additional load of the sidecar laden. The shocks are fully adjustable - and it will not be difficult to find the appropriate spring rate - so that you have the ability once the new shocks are installed - to adjust within an acceptable range for your riding style.
The calculation Klaus did when i ordered my shock went as follows:
the sidecar weighed approx. 230lbs... add 100lbs for a cute girl 20lbs for some gear ... total weight +350lbs...
about 40% of the weight of the laden sidecar will be distributed to the motorcycle (or as an additional burden to the motorcycle suspension) ... 40% of 350 = 140lbs.
approx 40% of the additional load to the motorcycle suspension will be carried by the front shock... and 60% by the rear shock...
in this case ... 40% of 140lbs = 56lbs additional weight to the front
and 60% of 140 lbs = 84lbs to the rear...
take the stock settings from BMW for the front ... add 56lbs ... there is the spring rate range for the front shock...
take the stock settings for the rear ... add 84lbs ... there is the spring rate for the rear...
this is no hard fast rule ... but a way to approximate the spring size when ordering new shocks...
these are the calculations i did with Klaus - and i am extremely happy with the results...
it is a first class shock... and the range of adjustability is great ... i am not permanently stuck in a stiff setting... i can soften up the suspension quite a bit - or i can stiffen it quite a bit... and the shock operates fine at either end of the adjusted range...
as for changing the ride height... i am a big fan of low center of gravity... more of a formula 1 guy - than a monster truck guy - to put it in Claude's terms... especially considering some of the obstacles to handling built in to a GS/Ural rig...
the notes at the bottom of my order form from Klaus show this:
" [Spring: 59/59-245-175] A/A:381mm "
don't ask me what it means ... it is Klaus' handwritten note...
if i can be of any help... feel free to call...
Note: this method of calculation has been passed down from generation to generation to generation of suspension specialists... the original formula was painted on rocks in Baja Mexico over 2000 years ago... anyone who has ever ridden in Baja knows how important suspension set up is... this is an exact science... there is no other known formula... use it in good health
Ural guy wrote:
"Note: this method of calculation has been passed down from generation to generation to generation of suspension specialists... the original formula was painted on rocks in Baja Mexico over 2000 years ago... anyone who has ever ridden in Baja knows how important suspension set up is... this is an exact science... there is no other known formula... use it in good health"
But Fred didn't you know there was a smiley face at the end of those ancient writings with the words "yeah whatever behind it" :).
Many thanks to Fred for sharing his calculation. Having ridden your sidecar, I know from fact that these formulas give the GS rig a very nice handling.
By the way Claude, one more question. With the swaybar, should I get the same spring rate on the chair and on the rear of the bike, both shocks are working together, then it should make sense.
Your posts have a lot of justifications... Yes, being incredibly technical in the Kitchen... too much sometimes... and having dealt successfully with Ohlins and Penske's throughout my life on various 2 wheel bikes I might add with a lot of fun, I realize that personally one, well, me!... can get carried away by his desires... not realizing that... a sidecar rig is a sidecar rig and will always remain a sidecar rig!
I have Ohlins ight now on the GS... will change the springs on it soon and also replace the Ural wonderful Russian shock with another Ohlin also... why not have all three that will at least match and re-servicable every 20K or so...
Lots of knowledge here... I sincerely thank you for it...
Didier... just go ride the... D$%^& thing!!!... and get some new suspendion... will talk to you later... Be well... Ara
Originally written by twintwin on 8/18/2006 8:12 AM
Many thanks to Fred for sharing his calculation. Having ridden your sidecar, I know from fact that these formulas give the GS rig a very nice handling.
By the way Claude, one more question. With the swaybar, should I get the same spring rate on the chair and on the rear of the bike, both shocks are working together, then it should make sense.
Someone other than me would have to give a difinitive answer to that one Didier. I would probably say no as a sidecar rig is not really a balanced vehicle weight wise. I would also tend to determine spring rates, or at least establish a base line for them, with the swaybar not being factored in. By the way if anyone says they have the one and only answer to any of this I would be wary of it. Ara sai dit right..ride it and then decide where to go from there. You have to start somewhere. Fred expresed a way to begin but that is just that ....a beginning. If it suite you fine biut won't you always wonder if things could be just a little bit better? 🙂
What I also noticed, since this "adventure", is that one can get very close to a good handling situtation. As, you said, being an unbalanced rig... I call it "illogical"... how do we even know, myself anyhow, what is the perfect handling?... As everything lines up good... I have felt that it is more "getting used to it"! EVERY change in the geometry or front fork mod... or different tire pressure... even a full tank or empty tank... sometimes I even joke saying it handles differently depending on the weather!... I do believe that THAT it is the SPICE of driving this rig... the SPORT of it... predictable... but with so many more variances than 2 wheels... R turns... L turns... camber... wind... take off... braking... many more "physical reactions" than any other vehicles...
So as long as the safety factor is covered... that the feeling is solid... one should be fine and could start smelling the roses instead of letting the mind gears wonder internally to the "ifs" and "buts" of the handling possibilities...
Thanks you all (as they say here in the South...) for taking the time to "illuminate" out thoughts and knowledge...
Be well... Ara
Hi everyone.
Sorry to revive this thread, but I would like to update you on my suspension story.
After some advises from many members here, and some brain storming with Klaus from Wilbers USA, I get my new 3 shocks. The spring rate on the bike was calculated, taking in mind the weight of the chair (see Fred magic formula). The difference of handling with the new shocks is amazing, less chair‘s nose diving in the right turns, and much better feeling in the left one. I’m sure that Claude’ swaybar help, but the combination of new heavy shocks plus the swaybar make the rig much more predictable, comfortable and safer. You can see on the pictures the preload of the chair's shock on the right side, I did not yet play with the suspensions setting, but the factory one give me entire satisfaction so far.
http://twintwin.smugmug.com/gallery/2132041
Well, I will strongly encourage every sidecar owner, who has mounted a chair to a regular bike, to upgrade to heaviest spring; the result is really astonishing.
Didier
Hi Didier, your comments are appreciated.
I have a Suzuki V Strom w/Ural SC, and am in process of a friend (McGuyver type) installing a sway bar and other stuff. His first comment, after getting the rig, was that he thought my rear shock was pretty weak, and thought we should upgrade it 1st.
I called klaus at Wilburs (last week), he was very knowledgeable about the issue (probably due to you) and sold me a heavy duty spring for the stock shock ($100). He said if that wasn't enough i would need a custom shock, which would cost a bit more.
He also indicated that he thought 60% of the full SC weight was on the bike, and 60% of that was on the rear shock (i.e. 36% total). For me, that equates to around 150-175 pounds on the rear shock, which means, load wise, I am riding two up all the time! Never would have thought of it that way.
We added the spring (plus some other bling) and I pick up the rig tomorrow, taking it to Arizona for 10 days or so.
Can't wait to see what the new spring does for the handling.
Our plan is the add the sway bar when I return.
greg
Greg,
What we came up with Klaus.
Weight of Ural sidecar 250 lbs empty, 400 lbs fully loaded
The sidecar will add 40% (100lbs to 160 lbs) to the bike, and on the bike 40% of this 40% (40lbs - 70lbs) to the front and 60% of the 40 % (60lbs - 90lbs) to the rear.
I will strongly advise you to put also a heaviest front suspension, especially in the left turn the front of the bike is subject to extreme forces.
The Wilbers shock on the chair is a very nice addition to the rig, and can be set with the preload adjuster very easy. I remenber to have to take off the body of the Ural chair to change the setting, 2 positions, and no big difference. Klaus had my OEM ural shock in hand for a couple days to take the measurements, and the Wilbers one fit like a glove.
Enjoy your trip in AZ, went a couple months ago but with all the family and a 32' RV...
Thanks for the correction, I thought Klaus said 60% on the bike, versus 40%.Good idea on the front suspesion, we discussed it, and due to time constrainsts, decided to wait.
Never thought about changing the SC shock; other than cost, it's a pretty good idea.
I'll post when I get back, maybe sooner. I ride a lot in the twisties. I have thought of getting a HP SC from Hannigan, but awfully expensive.
Originally written by twintwin on 11/16/2006 3:03 PM
Greg,
What we came up with Klaus.
Weight of Ural sidecar 250 lbs empty, 400 lbs fully loaded
The sidecar will add 40% (100lbs to 160 lbs) to the bike, and on the bike 40% of this 40% (40lbs - 70lbs) to the front and 60% of the 40 % (60lbs - 90lbs) to the rear.
I will strongly advise you to put also a heaviest front suspension, especially in the left turn the front of the bike is subject to extreme forces.
The Wilbers shock on the chair is a very nice addition to the rig, and can be set with the preload adjuster very easy. I remenber to have to take off the body of the Ural chair to change the setting, 2 positions, and no big difference. Klaus had my OEM ural shock in hand for a couple days to take the measurements, and the Wilbers one fit like a glove.
Enjoy your trip in AZ, went a couple months ago but with all the family and a 32' RV...
