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Old 08-07-2005, 05:22 PM   #1
Yellow Pig OP
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Wicked 21" Wheel Test Ride on R1150GS

Living here in Colorado I get to do a lot of dirt w/ the Yellow Pig, so I thought it would be pretty sweet to have two sets of wheels for the GS. One w/ Anakees for the street & a second w/ TKC-80s for the dirt. I really hate riding on asphalt w/ knobbies because I can envision them wearing down as I ride. Then when I has at the Colorado HU 2005 Event in July I met a couple of guys that actually had 21” installed on their GSs and loved how the larger wheel performed in the dirt. cRaSH actually offered his GS up for a test ride(Thanx!).



Thanks to Tribeless I was able to purchase a spare set of GS Adventure wheels for my 2001 R1150GS. These I kept for my street tires since I didn’t want to loose the anodized rim. My original front wheel went to Woody of “Woody’s Wheel Works” in Denver to get converted to a lean and mean 21" dirt wheel. Woody did a great job w/ my front wheel in record time. He laced up a GS100 21” Baer rim to my original hub w/ BMW spokes. The price is not cheap, but you get what you pay for.



Here is a comparison on the 19” vs the 21” wheels :


Diameter comparison:


Profile:


My KLX-400 wheels compared to the GS wheel:


19" wheelclearance of fork brace:




21" wheelclearance of fork brace:




19" wheels side view:



21" wheel side view:


The whole bike in street mode:


and in dirt mode:


Tomorrow I'm doing the test ride and will add to the report. One thing to note is that it does make the bike sit up higher and list precariously when on the side stand:


It still goes onto the center stand, but barely. Both wheels touch the ground.

Thats all for now. I'm looking forward to letting you know how it runs in the dirt.
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Yellow Pig screwed with this post 08-09-2005 at 11:23 AM
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Old 08-09-2005, 11:22 AM   #2
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Laugh Wheel Test

After yesterdays 150 mile test ride here are my first impressions of the 21” wheel:



On the street at high speed on a curvy road the first thing I noticed was that the bikes speedometer finally matched up to my GPS speed. While cruising at 60mph I’m usually 5mph slower than what the GPS says. With the 21” it was spot on.



The bike’s steering felt much quicker, almost nervous and squirrelly. It no longer gave me the secure planted feeling that the 19” wheel does. Ya know that GSXR canyon carver feel. When shaking the handle bars I got quite a bit of driver induced head shake. Made it feel like I needed a steering damper. This was impossible to do w/ the 19”.

The other thing that I noticed was that in extreme braking conditions the ABS kicked in much sooner than usual, same thing when I did the test w/ the ABS off. I’m assuming this is due to the smaller contact patch of the tire and the increased torque provided by the larger diameter.



Form the street I moved on to a nice, graded compact dirt road:




This is the Hayden Burn area, still devastated years after the fire. I found it depressing to ride through so many miles of destroyed forest and found it quite a releife when I was finally back into green woods.






My impression was that on this kind of road, which for all practical purposes is like a paved road. I liked the feel of the 19” better. The same impressions I had on the road of the 21” persisted on the compact dirt.

At this point I decide to take the wheel into its element. Rough, rocky, rutted trails.

On these roads the advantages of the 21” wheel really stood out. This wheel really holds a line through the rough stuff. The 19” has a tendency to roll of the crown of the road and tend towards the low spots: ruts, dips etc.. The 21’ held its line really well. I was particularly surprised by how I was able to steer the bike out of ruts w/ this wheel. With the 19” I would have to ride the length of the rut in the trough.



Washboard and water ruts no longer posed a problem. Most irregularities were significantly smoothed out.




Home sweet home for the 21" wheel





It rolled over rock like it wasn't there.





Held a line through the rutts:



And generaly made the driver feel more competent than he really is:



Driver & Test bike in a pose:



More secret test track:







Then the Yellow Pig got tired so I parked it for a quick nap:



Here is the one situation where the 21" wheel will not help:



It really sucks when this happens and you are by yourself and cannot get the fat Pig back up on the trail:



I ought to sue. No one posted a soft shoulder sign on this trail!

Nothing else to do here than point the big beast down hill and go for a ride to the next switch back.


Overall I was quite impressed w/ the 21" performance. On the drive back, now that I had a few more miles with that wheel under my belt, it felt more stable and planted than my first impression reveled.
I will say that this wheel is a must for the serious off roader, but I would not want it as my only front tire. I'm fortunate enough to have two complete sets.

So if your idea of off-road is a nice packed dirt road keep the 19".
If you venture farther out into the wild this is the wheel for you.

Later Dan

PS Notice the Buell turn signals? The look pretty good and are only $6.50 ea, instead of BMW Big $$$$$$. The Buell trurn signals are very flexible and can take a puch!
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Yellow Pig screwed with this post 08-10-2005 at 06:15 PM
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Old 08-09-2005, 12:09 PM   #3
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NIce !!
Wish I had been there to help lift the YPig.

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Old 08-09-2005, 12:42 PM   #4
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I think your ABS is freaking out because you now have a differential between the rotation rates of the front and back wheels. The front is turning slower and the computer thinks it's about to lock up, even on dry pavement.

This will cause your abs to release the brakes under the slightest of slippage in the front.

For safety's sake, I think you need to disable ABS every time you start the bike with the 19" wheels on.

Either that, or have a custom ABS ring machined with more "teeth" on it. Don't ask me how to do the math, but it's not complicated. Maybe BMW has one that would work.

...or get a larger rear wheel too!

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Old 08-09-2005, 12:45 PM   #5
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Question

Thanks Dan!

Really good post, very informative!

I have the GS Adv model, so it's same as your bike, but do you have any info on R12GS front wheel? I know that the back wheels are complitely different. will this fron wheel fit R12GS or it will requare different hub?

Thanks again!
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Old 08-09-2005, 01:06 PM   #6
Yellow Pig OP
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Quote:
Originally Posted by Phloodpants
I think your ABS is freaking out because you now have a differential between the rotation rates of the front and back wheels. The front is turning slower and the computer thinks it's about to lock up, even on dry pavement.

This will cause your abs to release the brakes under the slightest of slippage in the front.

For safety's sake, I think you need to disable ABS every time you start the bike with the 19" wheels on.

Either that, or have a custom ABS ring machined with more "teeth" on it. Don't ask me how to do the math, but it's not complicated. Maybe BMW has one that would work.

...or get a larger rear wheel too!
Could be, but it was locking up faster w/ the ABS off also.
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Old 08-10-2005, 09:29 AM   #7
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great pics,,but i ca n hardly read the print,

[QUOTE=Yellow Pig]After yesterdays 150 mile test ride here are my first impressions of the 21” wheel:



On the street at high speed on a curvy road the first thing I noticed was that the bikes speedometer finally matched up to my GPS speed. While cruising at 60mph I’m usually 5mph slower than what the GPS says. With the 21” it was spot on.



The bike’s steering felt much quicker, almost nervous and squirrelly. It no longer gave me the secure planted feeling that the 19” wheel does. Ya know that GSXR canyon carver feel. When shaking the handle bars I got quite a bit of driver induced head shake. Made it feel like I needed a steering damper. This was impossible to do w/ the 19”.


dan please edit and use a larger font,,,thanks woody
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Old 08-10-2005, 09:32 AM   #8
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we can lace it

Quote:
Originally Posted by CarbonCat
Thanks Dan!

Really good post, very informative!

I have the GS Adv model, so it's same as your bike, but do you have any info on R12GS front wheel? I know that the back wheels are complitely different. will this fron wheel fit R12GS or it will requare different hub?

Thanks again!
FYI>>>>i can lace darn near anything to anything,,,have rims and spokes that will fit the 1200GS...will check if 1100/1150 front hub will work on the 1200GS....holler,,,woody,,303-936-0232

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Old 08-10-2005, 09:40 AM   #9
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it's the contact area!!!

Quote:
Originally Posted by Yellow Pig
Could be, but it was locking up faster w/ the ABS off also.
that's because you have considerably less contact patch area,,,especially with the TKC-80,,,,if you had a street tire on there it would make a quantum difference in the contact patch,,,you are on the tips of the knobs!!! not much contact area!!!..... remember,,, we intended it to be a trail burner,,not a road burner

as for the abs freaking out,,,,,,i turn the abs off on the trails all the time

what surprises me is that you felt it steered quicker,,,by raising the front end an inch,,,trail actually is lengthened resulting in slower steering characteristics,,,it's what helps in the rough stuff...IMHO it's the tkc-80 that's the cause of the symptoms

others complain about the squirrliness of the tkc-80s....check this thread.... http://www.advrider.com/forums/showthread.php?t=90217

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Old 08-10-2005, 11:06 AM   #10
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Quote:
Originally Posted by Phloodpants
I think your ABS is freaking out because you now have a differential between the rotation rates of the front and back wheels. The front is turning slower and the computer thinks it's about to lock up, even on dry pavement.
The ABS works perfectly with the 21". Don't have to worry about that one.
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Old 08-10-2005, 01:35 PM   #11
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Changing the center of gavity with the 21"

Quote:
Originally Posted by Yellow Pig
Could be, but it was locking up faster w/ the ABS off also.
You have changed the center of gravity and weighted the rear more by raising the front end 1" then under stock conditions. The front now carries less weight which is felt especailly under braking. Because it is Telelever there is not a huge weight transfer forward under braking....
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Old 08-10-2005, 05:55 PM   #12
Yellow Pig OP
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Laugh

The few gripes I have of the wheel on road are minor and irrelevant. I got the 21" wheel for OFF-ROAD use. In those conditions the bigger wheel really rocks and can't be beat. I wouldn't trade it out for anything short of a Motozilla front fork set-up.

Thanx Woody, the wheel rules the dirt!!!!!!!!!!
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Old 08-11-2005, 05:51 PM   #13
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Nice post Dan. Been thinking of doing the same.
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Old 08-11-2005, 06:00 PM   #14
dieter von hexhead
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The larger front wheel has changed the geometry, you can compensate with
a shorter torque arm on the paralever if you want to slow the steering...
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Old 08-12-2005, 03:41 AM   #15
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How about on soft sand? I put a motocross rear tire on my front 19" rim. It was 100/90/19. Helped a lot in the soft stuff.
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