Center of gravity

Willsmotorcycle

Willsmotorcycle

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Joined
Oct 26, 2020
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2,008
Location
Makefield Highlands PA
Bike
2016 ST1300P
2025 Miles
000104
I read post or thread here about someone saying the ST1300 only handled well with no fuel in it. I suspect they could lose the offset fuel weight somewhere else, but here is why.

www.cycleworld.com

Motorcycle Center of Gravity Motorhead Myths

Does a low center of gravity improve handling? Kevin Cameron says it depends on what kind of handling you are after and it isn’t the answer to quick-handling sportbikes.
www.cycleworld.com www.cycleworld.com
 
That's funny, I find mine handles better with a full tank, and/or a passenger.
Folks who complain about handling are usually the folks who sit straight up etc..
If you want to find the sweet spot lean forward a bit.
 
Bike handles best with full tank and stock bars. With tall risers and the tank empty the rider and engine masses produce a larger polar moment of inertia than when the space between those separated masses (the fuel tank) is filled, and the rider is down a bit closer to the center of mass. Great article by Kevin by the way. I remember being surprised that Honda thought a bike leaned around an axis defined by the tire/road interface. You can see that's not the case riding a bicycle through a puddle and onto a dry surface observing the tire tracks where you've turned.
 
I asked a former MIT engineering professor about why my Honda NT700V seemed more stable as I approached a stop light, staying upright while barely moving, in comparison to the Suzuki Burgman scooter I had before. The Honda had a lot of weight up high. Gas tank, vertical twin, etc. The Suzuki had the weight down low.

His reply was interesting. He said to try balancing a pencil on your finger. You'll find it much easier to balance if you have the eraser with the metal band around it at the top. Put that eraser on the bottom, and it is impossible to balance.

Chris
 
Daboo said:
He said to try balancing a pencil on your finger.
Click to expand...

Yet a [new] pencil has drastically different "proportions", i.e., it's "height" (when balancing) in relation to its width and length and weight distribution (i.e., along its height). Cut the pencil to 1/4 or less and how does the balancing test go?
 
All very interesting, especially for those looking for performance.

Since I view the ST1300 as a touring bike first, I wouldn't mind if it were less "sporty" and more stabile. That's clearly not for everyone and the St1300 strikes a great balance which is why I'm surprised they weren't popular enough to still be produced.

One day, I hope to buy a GoldWing. I know that the loss of "flickability" won't bother me at all, but it's resistance to buffeting from side winds will serve me well.
 
I remember reading Kevin's articles in bike magazines decades ago, and learning a lot! The Honda ELF racing team tried the bottom-mounted tank and the handling sucked big-time. There's no doubt that a bike rolls around the CG of the bike/rider combination, usually somewhere around the top of the engine.

That's why counter-steering works. If a bike was moving along inside, say, a large pipe, it's easy to see how you would have to steer the front wheel up one side of the pipe to lean the bike the other way, as if the bike was free to rotate around an imaginary long rod running through the bike along the length of the pipe.
 
Igofar said:
Folks who complain about handling are usually the folks who sit straight up etc..
Click to expand...
I ride sitting straight up - unless I'm in a rush. I also have risers fitted to help with the whole sitting up thing.

Bike handles just fine (once I remembered how to ride again), and now, I positively love leaning over at about 2mph going into a junction & then getting on the gas to make her stand up again.

I've also added a screen topper fairly recently. Only downside to that is that I need to remember to wash it.

If I'm worried about the CoG while riding, I'm probably doing it wrong.
 
caldercay said:
I assume, leaning at 2mph, you're falling over more times than you'd prefer ...
Click to expand...
Not at all... as you're about to set off, letting the bike lean over, then positively applying throttle & steering... most if not all bikes will pick themselves up again.
Willsmotorcycle said:

Skip to 1:01 this maybe what he means @caldercay
Click to expand...
More or less - though it can also be done by rolling to an almost-stop, then let the bike "fall" to the side a little as you get back on the go juice.
 
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