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Old 09-23-2013, 04:05 AM   #1
twintwin OP
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Ground clearance

I guess this topic was never address yet, so here it goes.
I have a R1150GSA with CMS subframe and chair. The ground clearance of the bike, under the skid plate is 6" and the one under the frame of the chair is double, 12". Does it make sense, knowing that more the center of gravity of the chair is high, more likely it will take off in the right turns. In any 4 wheelers, the ground clearance is the same, left and right, front and rear. So why in the dual sport rig, such a difference??
Does anyone have try on the CMS setup to lower the chair? playing with the mounts.
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Old 09-23-2013, 04:25 AM   #2
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Couple of reasons that it is handy.

You get to focus on picking a line for the bike and not have to worry about the chair frame high centering. The sidecar tyre will look after itself and roll over shit. Go watch RTWDoug on his tat ride.

Two track where 4x4's with 35" + tyres have made the ruts fairly deep you once again don't have to constantly pick a line to also favour the chair frame.

GS's tend to be one wheel drive with the chair wheel set back from the front over hang. The higher the chair the less chance of it getting snagged or digging in when crossing/dropping into gullies/washes.

Most importantly ... they look as mean as cat piss parked up in town.
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Old 09-23-2013, 05:41 AM   #3
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Couple of reasons that it is handy.

You get to focus on picking a line for the bike and not have to worry about the chair frame high centering. The sidecar tyre will look after itself and roll over shit. Go watch RTWDoug on his tat ride.

Two track where 4x4's with 35" + tyres have made the ruts fairly deep you once again don't have to constantly pick a line to also favour the chair frame.

GS's tend to be one wheel drive with the chair wheel set back from the front over hang. The higher the chair the less chance of it getting snagged or digging in when crossing/dropping into gullies/washes.

Most importantly ... they look as mean as cat piss parked up in town.
Thanks for the explanations, those raisons could make sense if you ride off road on ruff terrain. In my case, I will only go on road and occasionally on gravel trails as I have a L.L. and car tires all around with no aggressive thread. I have GS only for the ergonomics of the bike, I'm 6"6' and it fit me OK. So does it make sense to lower the chair in this case, if it is possible.
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Old 09-23-2013, 06:44 AM   #4
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I'm with FR 700 unnecessary. THe center of gravity is under the bike no matter what.


Dragged the subframe a bit here with 240 pounds in chair.

One wheel drive, straddle when it's dry always the best option.DB
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Old 09-23-2013, 08:22 AM   #5
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Originally Posted by twintwin View Post
Thanks for the explanations, those raisons could make sense if you ride off road on ruff terrain. In my case, I will only go on road and occasionally on gravel trails as I have a L.L. and car tires all around with no aggressive thread. I have GS only for the ergonomics of the bike, I'm 6"6' and it fit me OK. So does it make sense to lower the chair in this case, if it is possible.
Didier, you can lower the chair with no problem if you do not need the ground clearance for off road riding. I do not remember the setup on yours as to whether or not it is possible to lower it but I do not think in your case lowering it would be a problem if you can.

I only have 8 inches of clearance on everything and I can still get it off road with no problems so I am sure you could get away with 6 inches all of the way around.

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Old 09-23-2013, 09:13 AM   #6
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Thanks Dana and Dave for your replies. As I will stay most of the time on road (my L.L. set up and care tire will put me in trouble in tuff off road riding), do I will feel some positive reactions of the rig on road ??? (especially stability in the turns) if I lower the chair by, let say 4" (so from 12" now to 8"). I ask this question before playing with all the mounts, cause there are so many bolts to loose, and studs to move. So not worth the pain if lowering the chair will not make any difference.
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Old 09-23-2013, 09:28 AM   #7
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Only thing to remember is that you want the sidecar frame level so if you lower the connections at the bike the sidecar wheel side will need to be lowered also to keep the frame level. You do not want one side of the frame higher then the other, especially by 6 inches.

I personally do not think you will notice much difference in handling by lowering it, that comes more from suspension travel.
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Old 09-23-2013, 01:13 PM   #8
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Quote:
Originally Posted by twintwin View Post
Thanks Dana and Dave for your replies. As I will stay most of the time on road (my L.L. set up and care tire will put me in trouble in tuff off road riding), do I will feel some positive reactions of the rig on road ??? (especially stability in the turns) if I lower the chair by, let say 4" (so from 12" now to 8"). I ask this question before playing with all the mounts, cause there are so many bolts to loose, and studs to move. So not worth the pain if lowering the chair will not make any difference.
Didier
I think the trouble will arrive in that you will need a shorter shock and will loose travel on the sidecar swingarm side to level the frame with the attachement side.THe attachement easy but a shorter shock is all that will lower the right side.DB
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Old 09-23-2013, 01:41 PM   #9
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Old 09-23-2013, 02:44 PM   #10
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Originally Posted by davebig View Post
Didier
I think the trouble will arrive in that you will need a shorter shock and will loose travel on the sidecar swingarm side to level the frame with the attachement side.THe attachement easy but a shorter shock is all that will lower the right side.DB
I guess that I could lower the swingarm playing with the "manual tilt".
So again, with a lower ground clearance on the chair, would I have a better handling in the turns ???? The HP rig lick the asphalt, chair and bike same ground clearance. The logic would say that I will have some cornering improvements if I reduce the height of the chair!
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Old 09-23-2013, 03:01 PM   #11
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Quote:
Originally Posted by twintwin View Post
I guess that I could lower the swingarm playing with the "manual tilt".
So again, with a lower ground clearance on the chair, would I have a better handling in the turns ???? The HP rig lick the asphalt, chair and bike same ground clearance. The logic would say that I will have some cornering improvements if I reduce the height of the chair!
I'm againest it as you may still want to go here and there, I suspect your a trout fisherman and there are allot of obstacles to lowering everything. See how much you can lower it with the shock adjustment but really you should have thought about this at the begining and lowered the GS with say an 1.5"shorter shocks, it is what it is a GS based setup but the center of gravity is under the bike, three 175/65/15 tires will take you down about an 1.5 " also and give you less sidewall flex and you'll feel like a F-1 driver or better yet http://www.tires-easy.com/cgi-bin/rs...hen=View+Tires
leave it as it is and hang these on preload the swaybar on the tug side and walla your Alain Proust !!!!!!
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Old 09-23-2013, 03:24 PM   #12
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Quote:
Originally Posted by twintwin View Post
I guess that I could lower the swingarm playing with the "manual tilt".
So again, with a lower ground clearance on the chair, would I have a better handling in the turns ???? The HP rig lick the asphalt, chair and bike same ground clearance. The logic would say that I will have some cornering improvements if I reduce the height of the chair!


Define " better handling in the turns " from your perspective.

As Dana said , most of the body roll is induced by the softer suspension and the amount of travel ( chair lifting/getting light has as much to do with the bikes suspension ). As soon as you start cornering weight transfers to the outside so one side compresses while the other extends. As the sidecar suspension is unloading all the mass of the swing arm , tyre , shock etc isn't coming into play yet to add to the counterweight/ballast so it comes up earlier.

Yes it will handle different. Whether the difference is great enough to warrant all that work will depend on how it ' feels ' to you.

You may well find that just adding a swaybar will get you to the point where the outfit feels more stable.


* edit , you'll also have to address the issue of altering the guard mountings if you lower the chair that much.



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Old 09-23-2013, 04:23 PM   #13
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I'm againest it as you may still want to go here and there, I suspect your a trout fisherman and there are allot of obstacles to lowering everything. See how much you can lower it with the shock adjustment but really you should have thought about this at the begining and lowered the GS with say an 1.5"shorter shocks, it is what it is a GS based setup but the center of gravity is under the bike, three 175/65/15 tires will take you down about an 1.5 " also and give you less sidewall flex and you'll feel like a F-1 driver or better yet http://www.tires-easy.com/cgi-bin/rs...hen=View+Tires
leave it as it is and hang these on preload the swaybar on the tug side and walla your Alain Proust !!!!!!
The R1150GS rig is already 1.5" lower than my R1100GS rig, due to the L.L. that drop the front and I put a regular R1150GS shock in the rear.
I guess I will give it a try, maybe when I will back from India next summer.
For the record, Alain Prost was a famous French F1 racer, and Marcel Proust was a famous French novelist.
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Old 09-23-2013, 04:29 PM   #14
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Originally Posted by FR700 View Post
Define " better handling in the turns " from your perspective.

As Dana said , most of the body roll is induced by the softer suspension and the amount of travel ( chair lifting/getting light has as much to do with the bikes suspension ). As soon as you start cornering weight transfers to the outside so one side compresses while the other extends. As the sidecar suspension is unloading all the mass of the swing arm , tyre , shock etc isn't coming into play yet to add to the counterweight/ballast so it comes up earlier.

Yes it will handle different. Whether the difference is great enough to warrant all that work will depend on how it ' feels ' to you.

You may well find that just adding a swaybar will get you to the point where the outfit feels more stable.


* edit , you'll also have to address the issue of altering the guard mountings if you lower the chair that much.

.
Thanks for the dynamic explanations, heavy hyperpro shock are already scheduled, and the swaybar is already there.
What do you mean by "altering the guard mounting"?
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Old 09-23-2013, 04:55 PM   #15
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Originally Posted by twintwin View Post
Thanks for the dynamic explanations, heavy hyperpro shock are already scheduled, and the swaybar is already there.
What do you mean by "altering the guard mounting"?

From memory the guard is solid mounted to the frame , as in it's not mounted to the swingarm where the clearance stays static between the tyre and guard.
That being the case if you lower the frame four/six inches that's four/six inches less clearance between the tyre and guard when the suspension cycles.

Welcome to the world of modifying things

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