Gyroscopic precession - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
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post #1 of 13 Old 04-02-2016, 05:50 PM Thread Starter
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Gyroscopic precession

Yes motorcycles do lean into the wind by themselves I know that experentially.

I knew that gyroscopic precession was involved but didn't understand what frame geometry had to do with it. I found this explanation most helpful.

"Yes, most bikes are self-correcting. A gust causes the steering axis to translate away from the wind side. (The gyro effect of the rear wheel tends to restrain the bike's rolling more than it prevents the frame from yawing, because of the leverages involved. The frame yaws, and the steering head translates.) The contact patch, due to trail, is behind the extension of the steering axis. Therefore, in a crosswind from the left, the steering axis moves slightly to the right. The contact patch is then slightly to the left of the steering axis, meaning that the bike is steering itself to the right. This banks the bike to the left, into the crosswind.

You can take your hands off the bars entirely, and this feature works just fine."

This makes sense to me as I think about what happens in a crosswind. There is an initial slight movement downwind followed by the bike leaning into the wind. Basically the bike is counterstreering itself.

"Here's an interesting photo showing how a bike automatically leans into a 50 mph side wind blast coming out of the fans in the building at the left"

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Last edited by Spec; 04-02-2016 at 09:48 PM.
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post #2 of 13 Old 04-02-2016, 06:38 PM
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I'm not sure the bike does it by itself. Ride input to compensate for the wind may come into play, otherwise the bike would accept the input and head for what ever way the wind blew.
At least that's my experience and I'm sticking to it!
I've had winds blow me and the sidecar across lanes of traffic. Without rider input, I don't think it would have compensated worth a dang. Bar Ditch time!
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post #3 of 13 Old 04-02-2016, 07:08 PM
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Gyroscopic precession can best be seen when stunt riders and motocrossers cross up a bike in mid air. With wheels on the ground, lean is controlled by countersteering and to a much smaller extent, side wind and body weighting. Even then it's rake and trail influencing steering when the hands are off the bars that keeps a bike stable to a much greater degree than gyroscopic precession or weight shift. The weight of the bike is much greater than the weight of the wheels. Put vertical forks on a motorcycle and you'll have a hell of a time riding it, even though the gyroscopic forces from the wheels would be unchanged.

A snow ski bike works just fine, steering like any bicycle or motorcycle without wheels.


Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
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post #4 of 13 Old 04-02-2016, 08:56 PM
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Thanks Spec! It's what I've been saying for quite a while and I think I just posted essentially the same thing the other day (but real nice to see the line
Is confirming what I've thought!

..Tom

2006 DL650: 202,000 km 125,500 miles, Sold
2012 DL650 139,500+ km, 86,700+ miles. Sold
2015 DL1000 New July 2015 193,000+ km, 120,000 miles.

This can help preventing from cars pulling out in front of you (SMIDSY)
SMIDSY detailed report.


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post #5 of 13 Old 04-02-2016, 10:42 PM
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The bike will right itself if an outside force hits the side, but it's mostly because the side push creates a handlebar movement so the bike countersteers itself. At about 2:45 in this video, the rider uses weight shift to create a small force to the side like a side wind might and the bike countersteers itself as a result.

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Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
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post #6 of 13 Old 04-03-2016, 12:17 PM Thread Starter
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Quote:
Originally Posted by greywolf View Post

The bike will right itself if an outside force hits the side, but it's mostly because the side push creates a handlebar movement so the bike countersteers itself. At about 2:45 in this video, the rider uses weight shift to create a small force to the side like a side wind might and the bike countersteers itself as a result.

No.

The bike doesn't right itself if a force (wind) hits the bike. Just the opposite. The bike leans into the wind as explained.

If you think that weight shift is turning the bike in that Keith Code video uhh...
Keith goes to great lengths to prove that counter-steering is the only way a motorcycle turns at speed. He even built a bike to demonstrate that.

Motorcycle Countersteering and the No BS Bike

Why do you have to counter-steer after a certain speed? The frame geometry hasn't changed. It's the spinning wheels. They generate enough force that the rider can't turn the tire into the turn.

BTW - The ski bike turns on the ski's edges, no gyro action involved.

And now these three remain: faith, hope and love. But the greatest of these is love. 1 Cor 13:13

Last edited by Spec; 04-03-2016 at 12:22 PM.
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post #7 of 13 Old 04-03-2016, 12:39 PM
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I think I'm going to leave it at the disagreement. I see doing otherwise a waste of energy for no good result.
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Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
See https://www.stromtrooper.com/general-...nicknames.html

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post #8 of 13 Old 04-03-2016, 10:03 PM
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When the wind hits me I think about changing the oil. Can anyone recommend which oil I should use?

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post #9 of 13 Old 04-04-2016, 11:36 AM
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The only time a bike of mine has leaned into the wind is a dirt bike in the air when a side wind tends to push the bike away from beneath you. Next time around I would ride to the upwind side of the track, knowing that the wind will move me and the bike in the air in the direction that the wind is blowing.
On the road it always blows me in the direction the wind is going and rider input is required to counter its effect. Some of you guys must be smoking really good stuff.
and p.s. you quote an Adventure Rider forum opinion as scientific proof of your theory?
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post #10 of 13 Old 04-04-2016, 11:54 AM
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The right itself force I mean is that the wind won't blow the bike over, the steering will compensate itself to keep the bike from falling over but turn in the direction of the wind induced lean as a result. I didn't mean it would compensate by keeping its line. Rider input is required to do that.
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Pat- 2007 DL650A was ridden to all 48 contiguous states. I didn't quite make it to 17,000 miles on the 2012 DL650A.
Nicknames I use to lessen typing, Vee = 2002-2012 DL1000s. Vee2=2014-2016 DL1000s. Wee = 2004-2011 DL650s. Glee = 2012-2016 DL650s
See https://www.stromtrooper.com/general-...nicknames.html

Please vote in the poll on what Strom(s) you have at https://www.stromtrooper.com/informat...-you-have.html
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