Any one notice anything happening to the way the bike handles passing an 18-wheeler/tractor trailer?

It seems to me that as I am about 5-10 feet behind the cab, the turburlance momentarily produces a sensation of being pulled closer to the truck. To the point where I countersteer slightly to the left to correct for it.

Yup.

Hey remember that movie where the trucks came alive and started to kill everyone? Yeah, that was a good one.

Maximum over drive? SK should have stuck to writing.

Yes, now you know why making a pass in a turn in a NASCAR is not as easy as it looks when at the limt of grip doing 198 MPH.

Air pressure. Give larger vehicles more room or you'll end up like that guy in the "Video" section... I usually lag a bit to get some room and then pass them with some speed. I hate when a car pulls up even with the truck and then goes the same speed... :evil:

Hey remember that movie where the trucks came alive and started to kill everyone?

But the chicks were cute, weren't they? :P

Air pressure. Give larger vehicles more room or you'll end up like that guy in the "Video" section...

Thanks, I'll move more to the left in the future. Sometimes I just don't know if I am crazy or not and I keep on thinking about whether I'm going crazy or not...and I keep on thinking about whether I'm going crazy or not...

I do appreciate it. :)

Yup.

Hey remember that movie where the trucks came alive and started to kill everyone? Yeah, that was a good one.
There was a better one in the 70's with Dennis Hopper (I think) as guy getting terrorized by a psychotic trucker. In the end, he manages to get the trucker to go over a cliff. Lots of property destruction, dust spewing, etc. Not much gore until the final scene when you see blood dripping off the truck's steering wheel.

Anyway, yes, I'm familiar with the pull. I agree with the strategy to get a little room then zoom on by. You don't notice the turbulence so much that way.

Hey remember that movie where the trucks came alive and started to kill everyone? Yeah, that was a good one.
There was a better one in the 70's with Dennis Hopper (I think) as guy getting terrorized by a psychotic trucker. In the end, he manages to get the trucker to go over a cliff. Lots of property destruction, dust spewing, etc. Not much gore until the final scene when you see blood dripping off the truck's steering wheel.

Wasn't that "Duel?" Spielberg's first movie? Not his best work, but it definitely had a "feel."

Air pressure. Give larger vehicles more room or you'll end up like that guy in the "Video" section...

Thanks, I'll move more to the left in the future. Sometimes I just don't know if I am crazy or not and I keep on thinking about whether I'm going crazy or not...and I keep on thinking about whether I'm going crazy or not...

I do appreciate it. :)

It's because of the Venturi Effect: http://en.wikipedia.org/wiki/Venturi_effect

The air flow between you and the tractor trailer creates a venturi because of the constriction, so it moves faster, so there is lower pressure in that zone.

You ARE being sucked in closer to it.

-FT3

I wonder if NAFTA has anything to do with that giant sucking sound... :mrgreen:

Any one notice anything happening to the way the bike handles passing an 18-wheeler/tractor trailer?

It seems to me that as I am about 5-10 feet behind the cab, the turburlance momentarily produces a sensation of being pulled closer to the truck. To the point where I countersteer slightly to the left to correct for it. Back to your question. There is a wake (?sp) behind the truck. Think of water and a boat and you'll get a somewhat better idea. I commute 35 miles down I-40 one way to work, as well as ride the twisties. I am very familiar with this sensation. Behind the truck, as you start to feel it, you will find it gets quiet and is almost a decent place to ride. Unfortunately, I have had some bad experiences in my car that I don't care to repeat on my bike, with things being thrown up from trucks, so I prefer not to follow them. As you move to pass (ideally on the left), this sensation causes a bobble. As you pass, if you were to draw a backwards 'C' and put the apex of the 'C' around the center or just behind the cab of the truck, that kind of describes how this wind feels. You get sucked close, then get slung out. The best way to deal with this is to stay to the center (versus the right side of the lane) and just relax. The more you fight it, the more you get pulled in. This sensation can be altered by winds. Once you understand how this feels, it becomes a non-event.

It's because of the Venturi Effect: http://en.wikipedia.org/wiki/Venturi_effect

The air flow between you and the tractor trailer creates a venturi because of the constriction, so it moves faster, so there is lower pressure in that zone.


-FT3
I would have though it was the Bernouilli Principle (http://en.wikipedia.org/wiki/Bernoulli%27s_principle). The same effect that causes lift on a wing. In essence the same effect, but I thought a venturi was limited to the effect caused by restriction of the airflow.

I would have though it was the Bernouilli Principle (http://en.wikipedia.org/wiki/Bernoulli%27s_principle).
WTF...
For now the nod is with Bernoulli...Air is definitely compressible.

Just nail the fracking throttle and drive right on by. I'm on the slab about 25 miles one way to work and as long as the way is free and clear I'm on the throttle pretty good when I pass semis and the forward momentum pretty much cancels out the air bubble around the truck. It's not good to linger around those beasts for a number of reasons.

Cranberries ruined the word "linger"...

I've never really felt a steady push or a pull as I pass a truck, it seems to me more like a buffeting on a regular interval, so I've always assumed it was vortex shedding. http://en.wikipedia.org/wiki/Vortex_shedding

Bernoulli Principle does'nt explain why a plane can fly upside down. If his gas theory is right would'nt the plane wing "lift" itself into the ground? With the help of mr gravity of course. +1 speed on by I hate being near them.

I'm uneducated on the subject... don't the ailerons assist in flying upside down? I would think it would be nearly the same as holding the plane level except having to counter gravity pulling it in the opposite direction.

...always assumed it was vortex shedding. http://en.wikipedia.org/wiki/Vortex_shedding
Yeah, but what force(s) created the Vortex (http://en.wikipedia.org/wiki/Vortex)

Or maybe THIS (http://www.angelfire.com/indie/anna_jones1/vortexes.html) is the real answer...

SO, Sundog and his shedding vortexes now have nod, with a supporting nod to Motorico and his Bernoulli thingy...

http://en.wikipedia.org/wiki/Laminar_flow I just had to add this since it is science thursday everyone .

http://en.wikipedia.org/wiki/Laminar_flow. I just had to add this since it is science thursday everyone .

It is the opposite of turbulent flow. In nonscientific terms laminar flow is "smooth," while turbulent flow is "rough."
Ohhhhhhh... Snapperhead, you'll need to help me fit this into what's going on... :thinking

Thank goodness Science Thurs is about over... :wink:

Bernoulli Principle does'nt explain why a plane...

Bernoulli doesn't explaing anything (much) about how a plane flies... Newton took care of that much earlier (Law #3 I think mostly)... How Planes Can Fly (http://www.terrycolon.com/1features/fly.html)

Cool article on how planes fly rnd. I just felt left out and wanted to have a scientic theory to put forth. I beleive that Bernoulli once said at a party that "the airflow past the truck is laminar for a short time then becomes a motorcycle shaking venturi of shedding vortices. The result being a post in the riding tips section of Honda599.com. Pass the beer nuts"

It's because of the Venturi Effect: http://en.wikipedia.org/wiki/Venturi_effect

The air flow between you and the tractor trailer creates a venturi because of the constriction, so it moves faster, so there is lower pressure in that zone.


-FT3
I would have though it was the Bernouilli Principle (http://en.wikipedia.org/wiki/Bernoulli%27s_principle). The same effect that causes lift on a wing. In essence the same effect, but I thought a venturi was limited to the effect caused by restriction of the airflow.

Yeah, we are trying to say the same thing...
The Venturi effect can be derived from a combination of Bernoulli's principle and the equation of continuity. (http://en.wikipedia.org/wiki/Continuity_equation)

-FT3

I've never really felt a steady push or a pull as I pass a truck, it seems to me more like a buffeting on a regular interval, so I've always assumed it was vortex shedding. http://en.wikipedia.org/wiki/Vortex_shedding

OOOO I like this one!!

We need to see a shoot a truck thru a cloud and see what the vortices look like http://bp2.blogger.com/_25KicME4_Rc/RoxS1ifWUHI/AAAAAAAAAC4/ezzk9p4J4-Y/s400/1229391.jpg

-FT3