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Discussion Starter · #1 ·
Since this is my first bike with a shaft drive, I have to ask will I tear it up from riding wheelies with it?
 

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sportrider said:
Since this is my first bike with a shaft drive, I have to ask will I tear it up from riding wheelies with it?
Sure, if you crash it.

Other than that, the bike will just suffer the normal wear and tear associated with hard core riding. Will depend on how smooth you are at applying power and getting the front wheel off the ground and how hard you bring it back down to earth.

Just my two cents but, personally, I don't understand why someone wants to risk crashing or damaging a $17,000 luxury sport touring machine for no other reason than to "show-off."

Yeah, wheelies look cool if done right (i.e. Rossi crossing the finish line) but for the rest of us on the road, it's just senseless vanity. Every time I see one of those internet clips of some squid wrecking his brand new R1 trying to ride a wheelie or do a stoppie I cant help but think to myself "idiot,....serves him right."
 

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Drive shaft woes

I can't remember which site I read it on, but someone said that after numerous wheelies, he twisted his driveshaft into a corkscrew. Somehow he got the dealer to replace the driveshaft under warranty.
 

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Not logical....

MadMax said:
...someone said that after numerous wheelies, he twisted his driveshaft into a corkscrew. Somehow he got the dealer to replace the driveshaft under warranty.
There is no reason that a "wheelie" would, could, exert greater force on the drive shaft than maximum accelleration without a "wheelie". As a matter of fact, the front end coming up would reduce the force applied to the shaft, not increase it. "Popping the clutch" would add stress, however the tires should "break loose", or the front end should "flip backwards very rapidly" before the shaft could, should, exceed its design limit. BMW would be correct in covering a damaged shaft under warranty.



.
 

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Dangerous Advice

BillyOmaha said:
There is no reason that a "wheelie" would, could, exert greater force on the drive shaft than maximum accelleration without a "wheelie". As a matter of fact, the front end coming up would reduce the force applied to the shaft, not increase it. "Popping the clutch" would add stress, however the tires should "break loose", or the front end should "flip backwards very rapidly" before the shaft could, should, exceed its design limit. BMW would be correct in covering a damaged shaft under warranty.



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Your statement that sudden acceleration puts as much or more force on the drive system as the mechanical dynamics involved in doing a wheelie is rubbish. Particularly on a motorcycle with a wheel base as long as the K1200S. As a professional engineer who deals with this kind of problem frequently let me assure you that although your bikes drive train should survive this stress for a time, it will without a doubt lessen the lifespan of the drive train components. I have done a number of wheelies on my K and often "get air" on hard shifts. I realize the slow but steady destruction this action brings to my drive system components and am willing to live with that result. I just think you should be informed before you tell someone else its ok and no harm is done.
Best regards,
Lightspeed
 

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sportrider said:
Since this is my first bike with a shaft drive, I have to ask will I tear it up from riding wheelies with it?
A while back there was a twisted/failed drive shaft or two reported however if you do a search on "drag racing" you may find some further info.

Cheers
Lenz
 

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Lenz said:
A while back there was a twisted/failed drive shaft or two reported however if you do a search on "drag racing" you may find some further info.

Cheers
Lenz
Good memory Lenz.

Here I am. http://www.k-bikes.com/forums/showthread.php?t=1397

By comparison to other sport bikes, this is a very difficult motorcycle to wheelie. Of course this is due to the long wheel base.

It will come up very easily in first however. A quick twist of the glad handle at about 10mph will send the front wheel into the air. No need to pop the clutch. Unfortunatley, I am not comfortable with first gear wheelies.

My twisted shafts came after 2nd gear attempts. If timed right I can get some really nice floaters in 2nd. If timed wrong or too much throttle given, it will break the rear tire loose and leave a long patch of rubber.

I can tell you that both of my twisted shafts came immediately after the tire broke free while attempting to lift the bke in 2nd.

They gave me the first one, but made it clear that BMW WILL NOT PAY for a twisted driveshaft. The cost of the last one was about $600.00 installed.

I did discover what BMW calls a "Racing Cardan Shaft" is installed in the Power Cup Bikes as part of the "Racing Kit" Francois5200
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"Racing" Cardan Shaft
I found this Adobe pdf document on the K1200R forum. It's the Technical Regulations of the BMW Motorrad Power Cup 2005.

http://www.bmw-motorrad.co.uk/com/e...p2005/home.html

Click on the link that's titled "technics."

Page 4 of this document contains a list that's called "Racing Kit." One of the items in this racing Kit is what they call a "Racing Cardan Shaft."

The "Race Cardan Shaft" is mentioned again at the top of page 10 in the section that describes the rear wheel drive.

I don't want to jump to conclusions here, but it looks to me that the Power Cup Bikes get a stronger shaft.

What exactly is a Cardan Shaft? Is that a general description of the type of shaft that's in our bikes, and a "Race" version of that is in the Power Cup bikes?

I'd like to know what other's think.

Thanks,

Franklin
 

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Francois5200 said:
What exactly is a Cardan Shaft?
The Cardan joint is the universal, attached to the end of the shaft, hence the name Cardan shaft.

car·dan joint [ krd'n jòynt ] (plural car·dan joints)

noun Definitions: type of universal joint: a universal joint that can rotate when out of alignment

[Early 20th century. After Gerolamo Cardano (1501-1576), Italian mathematician]

 

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Rickd,

Thanks for the response.

We also have the term "Racing Cardan Shaft" as part of the "Racing Kit"

We now know that it is a different (stronger) version of this shaft installed in the Power Cup Bikes.

I only mention this because I kept hearing "the shaft is strong because they use it in Power Cup"
 

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Check out the technical specs for the Power Cup. It sates:

3.2. Power transmission / rear-wheel drive
All the elements of the power transmission (cardan shaft) from
the exit point of the gearbox to the rear axle gears must be in
their original condition. Deburring, processing, polishing, adjustment,
addition or removal of material is prohibited.


 

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rickd said:
Check out the technical specs for the Power Cup. It sates:

3.2. Power transmission / rear-wheel drive
All the elements of the power transmission (cardan shaft) from
the exit point of the gearbox to the rear axle gears must be in
their original condition. Deburring, processing, polishing, adjustment,
addition or removal of material is prohibited.


Regarding the Technical Regulations http://www.bmw-motorrad.co.uk/com/en/index_frameset.html?content=http://www.bmw-motorrad.co.uk/com/en/fascination/motorsports/powercup2005/home.html


Yes, I read that first paragraph of section 3.2 on page 9.


Reading just a little further into that same section 3.2 at the top of page 10, it becomes evident that the shaft they are reffering to as being in original condition is the "Race" Cardan Shaft.


Page 4 clearly lists a Race Cardan Shaft as part of the Racing Kit that the Power Cup Version comes with.

This is just one of many items changed from the production bike. All of these racing items have to be in their original condition. They are still far different from what we have on our bikes.
 

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Guess I should have read the whole thing Francois. It's hard to find info on the race kit. I'd like to see a picture of the racing Cardan shaft. Got any?
 

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Hmm, so what is your conclusion here?

The shaft failed while the rear tire was spinning, but both wheels were on the ground? Just sounds odd (Not disputing your description, just trying to understand what is happening). It would seem that the spinning tire wouldn't put that kind of stress on the shaft, or does it occur because of the release of force? - Maybe an engineer can comment -

Did BMW give the reason this is not covered? If the failure is a complete mystery why wouldn't it be covered? If it is not a mystery, then they must have an explanation.

Is the cause of the failure related to the joint design? If it binds then the shaft can distort.

Shaft technology is not that specialized or new. Seems like a curious kind of problem for these things to have. For some reason it has my interest. You must be having a lot of fun the rest of the time. Hope they treat you right.
 

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The information directly from the guy riding the KR in drag races was that the KR was std apart from a Staintune muffler. There was no mention of a modified or racing specs drive shaft but that doesn't mean it wasn't overlooked or forgotten in the conversation. However I would think it highly unlikely for an upgraded shaft to have been installed and not mentioned given the nature of the discussion - there was absolutely not even a hint of bullshit or deception about the conversation.

If you look at the start revs from the drag racing thread, they aren't maximal. Excessive wheel spin and drive lost to wheelies would cost time. Smooth changing would also help continuous drive and accelleration. I have no drag racing experience so maybe an engineer can comment but I think the rear wheel drive force is at a maximum when there is zero tyre slip and the front wheel is just off the ground ie max drive moment.

Rereading my earlier "attack mode - do what you want and f#ck the expense" statements I have had a re-think. I strongly suspect there are major differences in the high immediate loads that a high revs / low speed wheelie places on the drive line. It's just maybe that a skilful drag racer puts less shock loaded changes on the drive line than someone popping wheelies and backing on and off the throttle sharply.

In any event given the bikes potential my personal opinion is the shaft should be stronger as std to fully cater to engine potential and apparently "unforeseen user loading" but for the moment - "if you bend it someones gonna have to mend it"

Cheers
Lenz
 

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Discussion Starter · #15 ·
Well, as much as I like to loft the front end on occasion, After reading this, I think I'll
keep the wheelies limited to my dirt bike. :mad:
 

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I'm sure that if a capable, motivated lawyer went through graphics supplied by BMW there would be a picture or two of a raised front wheel. Does this constitute an endorsement by BMW that this duty level is within intended design parameters and driveline specs. It could be argued that any subsequent failure of the driveline must be a production fault / design deficiency not rider error or abuse.

Cheers
Lenz
 
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