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Old 12-02-2011, 01:40 AM   #1156
troy safari carpente
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Quote:
Originally Posted by fetid_swamp View Post
torque effect?
go for a fang in an old swing axle vw beetle/baja/buggy/country buggy that has the conventional setup and then go for a fang in one that has reduction hubs fitted such that the transaxle spins in "reverse".

under throttle the conventional one squats while the one with the reduction hubs stands up.... to its stops.

Yeah... you are correct swampy and the phenomenon you describe is a trait of the older CV/swing axle design of rear engined VW buggies/baja's, as opposed to the CV's/reduction hubs in the modern rear engine/mid engine/rear transmission class 1/open buggies... which also afford masses of travel...!

dont know what this proves but it did remind me of many happy times fanging the old volksies.



RE the bmw/husky, i thought having the pivot and the cs at the same point just minimised the torque effect (squatting under accell). no idea really.
That was my basic understanding of the BMW countershaft design also...
*An iInteresting footnote; that I have read - both shaft drive, and even PDS or linkage suspension system (as opposed to conventional twin shock principle) have a significant effect on the way that torque/squat alters the rear suspension under acceleration and braking.

I'm sure that regardles of all the physics and tekniks surrounding this science, that whacking 26 liters of fuel above the rear subframe, does a lot to make these calculations a hell of a lot more complicated/critical!
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Old 12-02-2011, 05:09 AM   #1157
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What 690RR is talking about (I think) is the effect of the crank inertia as the revs increase. Accelerating a forward spinning crank will necessarily try and rotate the rest of the bike backwards around the crank. Accelerating a reverse spinning crank will try and rotate the bike forwards around the crank axis.

If you were floating in space on your Husky, fired up the engine and opened the throttle in neutral, you would start spinning forwards.

Whether this actually makes a difference on planet earth I don't know, because there's a hell of a lot of other stuff going on - the rear wheel is also accelerating (with it's own inertia), in the conventional direction, the chain pull is compressing the rear suspension, the bike is trying to accelerate out from under the rider holding the bars, which will result in their weight being transferred rearwards.

It might be fair to say that if you had two identical bikes, apart from the direction of crank rotation, and opened the throttle on both, the conventional crank would have slightly more weight transfer to the rear. That might be a good thing (more grip) or might not (lifts the front wheel and forces you to close the throttle to avoid looping).
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Old 12-02-2011, 05:19 AM   #1158
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Quote:
Originally Posted by uberthumper View Post
What 690RR is talking about (I think) is the effect of the crank inertia as the revs increase. Accelerating a forward spinning crank will necessarily try and rotate the rest of the bike backwards around the crank. Accelerating a reverse spinning crank will try and rotate the bike forwards around the crank axis.

If you were floating in space on your Husky, fired up the engine and opened the throttle in neutral, you would start spinning forwards.

Whether this actually makes a difference on planet earth I don't know, because there's a hell of a lot of other stuff going on - the rear wheel is also accelerating (with it's own inertia), in the conventional direction, the chain pull is compressing the rear suspension, the bike is trying to accelerate out from under the rider holding the bars, which will result in their weight being transferred rearwards.

It might be fair to say that if you had two identical bikes, apart from the direction of crank rotation, and opened the throttle on both, the conventional crank would have slightly more weight transfer to the rear. That might be a good thing (more grip) or might not (lifts the front wheel and forces you to close the throttle to avoid looping).
Excellent explanation 'Uberthumper'!
So what you are saying is the Husky would be the bike of choice for 'Travis Pastrana' to do a 'forward flip'!
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Old 12-02-2011, 10:10 AM   #1159
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there would also be some evident rotational forces perpendicular to the rotation of the crank. I think there's some threads on this somewhere, probably near the countersteering thread.....
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Old 12-02-2011, 10:57 AM   #1160
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There are lots of ways rotating mass and torque transfer can impact weighting of the rear wheel and suspension loading but I propose the overall effect to be minimal compared to shifting the rider weight or big rear fuel tanks.

Anyone who has spent time on a pre-Paralever BMW or Moto Guzzi has experienced these effects. Sit at a stop and blip the throttle and the bike tries to roll sideways from the change in rotational inertia of the engine and flywheel. Accelerate and the whole bike raises or close the throttle and the bike lowers (not a good idea mid turn). This effect is due to torque transfer through the gears in the final drive.

The effects are real but not substantial.
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Old 12-07-2011, 01:24 PM   #1161
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I moved some of the posts dealing with 2012 Dakar stuff to the Pre-Event Discussion Thread. I hope that makes it easier to follow the discussion.
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Old 12-08-2011, 02:20 AM   #1162
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A wee flashback, this was aired on Greek TV after Vassilis Orfanos became the first rookie in Dakar history
to win his class (the Sport Production back in 2003 on an XR400)

Pretty moving stuff from Ari Vataanen in the beginning, followed by Greek narration in the second part...

Don't know if it belongs here but I found it to be soul-stirring stuff seeing the privateer side of the race

(Unfortunately Orfanos will be skipping the Dakar this year due to the shitty economic climate here, from
what I gathered a big chunk of sponsorship money didn't come through)

youtube video
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Old 12-08-2011, 05:27 AM   #1163
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Originally Posted by Brodovitch View Post
A wee flashback, this was aired on Greek TV after Vassilis Orfanos became the first rookie in Dakar history
to win his class (the Sport Production back in 2003 on an XR400)

Pretty moving stuff from Ari Vataanen in the beginning, followed by Greek narration in the second part...

Don't know if it belongs here but I found it to be soul-stirring stuff seeing the privateer side of the race

(Unfortunately Orfanos will be skipping the Dakar this year due to the shitty economic climate here, from
what I gathered a big chunk of sponsorship money didn't come through)

youtube video
Nice video, thanks for posting this.
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Old 12-31-2011, 07:16 AM   #1164
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Cry Dunno About Anyone Else, ...

... but I'm already missing

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Old 12-31-2011, 07:24 AM   #1165
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... but I'm already missing

Yeah me too. Ping Jenny??
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Old 12-31-2011, 09:46 AM   #1166
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I (don't think I) have a Pinger but then a year ago I couldn't find the F5 button on the new keyboard so maybe I have a half-dozen and don't know it.
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Old 12-31-2011, 10:36 AM   #1167
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Yeah me too. Ping Jenny??
PM'd her - told her you said Howdy, too.
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Old 01-02-2012, 09:04 AM   #1168
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I've read through that one three trimes now Eskil... and I'm still not quite sure what you mean... Care to give it another shot for us...?

Hehe!
The nick "690rr" belongs to Vladmir "Vlado" Kusnier - one of Team Ullevalseter's mechanics.
But thanks for believing I know that much from inside the Dakar circus

I think Vlado deserves a BIG hand for sharing with us.

Go, Team Ullevalseter!
Pal Anders is now on 9th psn. - and Coma & Chaleco have passed WP4.
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F650Dakar_Norway screwed with this post 01-02-2012 at 10:33 AM
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Old 01-02-2012, 09:32 AM   #1169
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Nice video, thanks for posting this.
Very cool video, and I think there were a couple of shots of Meoni riding the 950, yeah? Awesome!
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Old 01-02-2012, 09:36 AM   #1170
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in San Rafael watching the trucks roll out to the bivaouc now.
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