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Offline JacoM

990R vs GS - first impressions
« on: September 30, 2010, 09:28:54 am »
I had the oppertunity to ride Ball$Chain's 990R at the CABC this week-end. Some old and some (I hope) new comments?
- Superior offroad suspension and grounclearance on the R (Punt!)

The handle bars are very narrow. I feld less in control when I got up on the pegs, due to the height of  the bike and the narrow bars. (less leverage). MAybe this explains why more GS riders stand up? The narrow seat makes it possible to shift your weight without having to stand up as on the GS. I found the R's seat very comfortable.

The engine is more responsive and revs very easily. The configuration of the pistons (upright V) has a very important impact on handling on dirt - AS the engine picks up speed, it "forces" the bike upright. I tested it on a very sandy patch and the R is a pleasure in sand! The bike is "forced" upright with the slightest engine revs and, in conjuction with the 21' front wheel, suspension and different weight distribution it was much easier to handle in the thick sand.

The only "negatives" I found was the following.
It was suprisingly heavier to pick up than the 1200GS. (Higher centre of gravity with even taller suspension to blame).
On the open dirt road I found it has less"stopping power". The back wheel slides easier with the brakes on - maybe the bigger wheel to blame which reduce grip?
(Grip is a funtion of weight and contact surface area. Bigger wheel=larger contact surface area and asuming the same friction coefficent leads to "less" grip)
Engine "wear and tear" is a function of engine speed, so the "higher reving" engine might have a shorter "life expectansy?

Must be said my "test ride" was only about 30minutes, so maybe I have it completely wrong? 
 
 

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Re: 990R vs GS - first impressions
« Reply #1 on: September 30, 2010, 09:32:01 am »
The call  of the Dark Side is strong!!!  ;)
There is nothing you can do about the past and you can't predict the future...all you have is the now...live it to the fullest.

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Offline Jacko

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Re: 990R vs GS - first impressions
« Reply #2 on: September 30, 2010, 09:52:43 am »
I had the oppertunity to ride Ball$Chain's 990R at the CABC this week-end. Some old and some (I hope) new comments?
- Superior offroad suspension and grounclearance on the R (Punt!)

The handle bars are very narrow. I feld less in control when I got up on the pegs, due to the height of  the bike and the narrow bars. (less leverage). MAybe this explains why more GS riders stand up? The narrow seat makes it possible to shift your weight without having to stand up as on the GS. I found the R's seat very comfortable.

The engine is more responsive and revs very easily. The configuration of the pistons (upright V) has a very important impact on handling on dirt - AS the engine picks up speed, it "forces" the bike upright. I tested it on a very sandy patch and the R is a pleasure in sand! The bike is "forced" upright with the slightest engine revs and, in conjuction with the 21' front wheel, suspension and different weight distribution it was much easier to handle in the thick sand.

The only "negatives" I found was the following.
It was suprisingly heavier to pick up than the 1200GS. (Higher centre of gravity with even taller suspension to blame).
On the open dirt road I found it has less"stopping power". The back wheel slides easier with the brakes on - maybe the bigger wheel to blame which reduce grip?
(Grip is a funtion of weight and contact surface area. Bigger wheel=larger contact surface area and asuming the same friction coefficent leads to "less" grip)
Engine "wear and tear" is a function of engine speed, so the "higher reving" engine might have a shorter "life expectansy?

Must be said my "test ride" was only about 30minutes, so maybe I have it completely wrong? 
 

In fact, it's the exact opposite. Theoretically a bigger wheel should provide better braking for the exact reasons you mentioned.

Things to consider vis-a-vis your GS:
1. Tyre pressure. Too hard and you have less grip.
2. Type of tyre. A Scorpion doesn't have the grip of, say, a TKC.
3. Strength of rear brake, ie, maybe you need to recalibrate your right foot to apply less force as to avoid locking up.

Ja, the KTM990R is a beast. If it had tubeless tyres I might have owned a KTM long time ago.

Who knows what the future will bring?
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Offline JO GSA

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Re: 990R vs GS - first impressions
« Reply #3 on: September 30, 2010, 10:03:15 am »
Ek het ook al gevoel dat op sekere kleiner bikes soos bv. XChallange en KDX mens in sommige situasies gemakliker voel as jy  sit, maar as dit regtig erenstig raak dat jy ook weer moet staan en ry. Die handlebars wat nouer is het ek nog nie agter gekom nie, maar ek dink jy het n punt beet daar. Wat betref die suspensie van alle KTM's, dink ek hulle is enige BMW ver voor wat off road betref. Maar dan weer wil jy nie regtig op n 990R van Jhb af Kaap toe ry nie, die 1200 GS se suspensie is net baie gemakliker wat dit aan betref.

So "horses for courses", net jammer n mens se plek en tyd is dikwils beperk, anders het ons almal 10 bikes gehaad, soos Sir Battery(Duracell) se langtermyn plan is  :thumleft:
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Offline JacoM

Re: 990R vs GS - first impressions
« Reply #4 on: September 30, 2010, 10:48:13 am »
Jacko, The R had Mitas tyres, simular to my Heidenau 50/50, so I assumed same pressures and rubber profiles. Assumptions might be wrong.

I  stand with my explination, if completely wrong I will have to go back to the Engineering prof, and ask my money back!
Maybe better to explain on paper with a full mathematical calculation, which I would be happy do .
WITH A FEW ASSUMPTIONS,
"Grip" = f(Force/Area x friction coeffecient)
Bigger radius tire=bigger contact surface area. This can be calculated. Assuming the same Force(i.s weight) and friction coeff(i.s same tyre profile and tyre pressure), the "grip" should be less.
This at least in theory.
I tested the "pressure on back foot" and in practise found the back to slide very easily.
 

Offline ROSY

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Re: 990R vs GS - first impressions
« Reply #5 on: September 30, 2010, 11:07:30 am »
Hi there guys, sorry off topic a bit but you guys sound as if you might be able to help me. I took ownership of a 2006 Gs 1200 yesterday and this morning after a short ride into town the bike did not want to start, we had to jump it and it started with ease. I thinik i need a new battery. BMW quoted R1500 for the part and track mac wants R615 for similar one. Question:: is it safe to go for the cheaper one?
 

Offline Ball and Chain

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Re: 990R vs GS - first impressions
« Reply #6 on: September 30, 2010, 11:10:19 am »
I warned you before the ride.  The tyre pressure was not dropped.  I don't like smileys.

The HP2 had TKC's on,  much better stopping power on gravel


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Offline Pistonpete

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Re: 990R vs GS - first impressions
« Reply #7 on: September 30, 2010, 11:11:49 am »
Hi there guys, sorry off topic a bit but you guys sound as if you might be able to help me. I took ownership of a 2006 Gs 1200 yesterday and this morning after a short ride into town the bike did not want to start, we had to jump it and it started with ease. I thinik i need a new battery. BMW quoted R1500 for the part and track mac wants R615 for similar one. Question:: is it safe to go for the cheaper one?
Use the "search" function bud or look up GS threads...i'm sure you will find the info required. :thumleft:
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Offline Kaboef

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Re: 990R vs GS - first impressions
« Reply #8 on: September 30, 2010, 11:12:34 am »

"Grip" = f(Force/Area x friction coeffecient)
Bigger radius tire=bigger contact surface area. This can be calculated. Assuming the same Force(i.s weight) and friction coeff(i.s same tyre profile and tyre pressure), the "grip" should be less.


The grip per cm2 is less. But the larger diameter tyre has more cm2 in contact with the ground, so the braking power should be more or less the same?

But I'm no Injuneer, so that is just like, my opinion, man.  ;D
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Offline EtienneXplore

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Re: 990R vs GS - first impressions
« Reply #9 on: September 30, 2010, 11:14:17 am »
Jacko, The R had Mitas tyres, simular to my Heidenau 50/50, so I assumed same pressures and rubber profiles. Assumptions might be wrong.

I  stand with my explination, if completely wrong I will have to go back to the Engineering prof, and ask my money back!
Maybe better to explain on paper with a full mathematical calculation, which I would be happy do .
WITH A FEW ASSUMPTIONS,
"Grip" = f(Force/Area x friction coeffecient)
Bigger radius tire=bigger contact surface area. This can be calculated. Assuming the same Force(i.s weight) and friction coeff(i.s same tyre profile and tyre pressure), the "grip" should be less.
This at least in theory.
I tested the "pressure on back foot" and in practise found the back to slide very easily.

Maar dit is dan die lekker deel !!!

 :biggrin:


Offline EtienneXplore

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Re: 990R vs GS - first impressions
« Reply #10 on: September 30, 2010, 11:25:29 am »
......It was suprisingly heavier to pick up than the 1200GS. (Higher centre of gravity with even taller suspension to blame). ......

The Katoom was heavier to pick up because it weighs more - simple as that....   ;D ;D ;D

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Dry weight: 207.0 kg (456.4 pounds)    -   http://www.bikez.com/motorcycles/ktm_990_adventure_r_2009.php

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Dry weight: 203.0 kg (447.5 pounds)   -   http://www.bikez.com/motorcycles/bmw_r_1200_gs_2009.php



« Last Edit: September 30, 2010, 11:27:15 am by KnopKop »
 

Offline man on the moon

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Re: 990R vs GS - first impressions
« Reply #11 on: September 30, 2010, 11:28:22 am »
Its always interesting to read these comparisons, I road the XT1200 for a short test the other day and would like to do the same with the 990, but the opportunity to really test these bikes off road to get the true impression of there handling does not happen that often.
Do the KTM guys ever do this ?
 

Offline zagser

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Re: 990R vs GS - first impressions
« Reply #12 on: September 30, 2010, 11:31:08 am »
......It was suprisingly heavier to pick up than the 1200GS. (Higher centre of gravity with even taller suspension to blame). ......

The Katoom was heavier to pick up because it weighs more - simple as that....   ;D ;D ;D

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Dry weight: 207.0 kg (456.4 pounds)    -   http://www.bikez.com/motorcycles/ktm_990_adventure_r_2009.php

2009 BMW R1200GS
Dry weight: 203.0 kg (447.5 pounds)   -   http://www.bikez.com/motorcycles/bmw_r_1200_gs_2009.php





That, and the fact that the pods have already done 50% of the lifting for you.  :biggrin:
 

Offline domstes

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Re: 990R vs GS - first impressions
« Reply #13 on: September 30, 2010, 11:38:12 am »
Its always interesting to read these comparisons, I road the XT1200 for a short test the other day and would like to do the same with the 990, but the opportunity to really test these bikes off road to get the true impression of there handling does not happen that often.
Do the KTM guys ever do this ?

I tested everything including the HP2 before the KTM 990 picked me.
 

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Re: 990R vs GS - first impressions
« Reply #14 on: September 30, 2010, 11:40:19 am »
Friction force is independant of surface area. F = mu x weight.

So it depends on the weight of the bike and the coefficient of friction of the tyre/ground.

In this case, assuming the same rubber compound and ground surface, the KTM actually has more stopping power, whether tyre is bigger or smaller.
 

Offline Rynet

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Re: 990R vs GS - first impressions
« Reply #15 on: September 30, 2010, 11:48:43 am »
What I  really value about the 1200 , besides the ABS brakes on tar , is that it doesn't nose -dive when you stop suddenly . But yes the KTM's are certainly lekker bikes for off -road riding  :thumleft:
 

Offline Pistonpete

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Re: 990R vs GS - first impressions
« Reply #16 on: September 30, 2010, 11:51:17 am »
What I  really value about the 1200 , besides the ABS brakes on tar , is that it doesn't nose -dive when you stop suddenly . But yes the KTM's are certainly lekker bikes for off -road riding  :thumleft:
With the .59 SE springs in this issue is alleviated :thumleft:
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Offline Rynet

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Re: 990R vs GS - first impressions
« Reply #17 on: September 30, 2010, 12:12:15 pm »
What I  really value about the 1200 , besides the ABS brakes on tar , is that it doesn't nose -dive when you stop suddenly . But yes the KTM's are certainly lekker bikes for off -road riding  :thumleft:
With the .59 SE springs in this issue is alleviated :thumleft:

Ok , but still the 1200 will stop better, faster and smoother ( hence safer ) than almost any other big bike in any terrain.  :peepwall: :pot:
« Last Edit: September 30, 2010, 12:12:55 pm by Rynet »
 

Offline Pistonpete

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Re: 990R vs GS - first impressions
« Reply #18 on: September 30, 2010, 12:14:57 pm »
What I  really value about the 1200 , besides the ABS brakes on tar , is that it doesn't nose -dive when you stop suddenly . But yes the KTM's are certainly lekker bikes for off -road riding  :thumleft:
With the .59 SE springs in this issue is alleviated :thumleft:

Ok , but still the 1200 will stop better, faster and smoother ( hence safer ) than almost any other big bike in any terrain.  :peepwall: :pot:
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Re: 990R vs GS - first impressions
« Reply #19 on: September 30, 2010, 12:15:32 pm »
What I  really value about the 1200 , besides the ABS brakes on tar , is that it doesn't nose -dive when you stop suddenly . But yes the KTM's are certainly lekker bikes for off -road riding  :thumleft:
With the .59 SE springs in this issue is alleviated :thumleft:

Ok , but still the 1200 will stop better, faster and smoother ( hence safer ) than almost any other big bike in any terrain.  :peepwall: :pot:

That is simply because its going the slowest! :biggrin:
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