BMW Luxury Touring Community - Reply to Topic
Thread: What Causes The High Center of Gravity? Reply to Thread
Title:
Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:
 

Register Now



In order to be able to post messages on the BMW Luxury Touring Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
Dec 15th, 2006 12:05 pm
zippy_gg
Quote:
Originally Posted by rmg08057
After a fast run thru Deal's Gap I've been sweating
Therefore motorcycling is a sport, and aerobic sport!!!
Dec 15th, 2006 8:32 am
UncleRock
Quote:
Originally Posted by mikeinpgh
and gravity ;D
Nice call
Knew I shouldn't have smoked that doobie before science class.
Rock
Wait can you have one with out the other?
Dec 15th, 2006 8:15 am
rmg08057 Joel

What you are saying is that the first turn is easier ....but on the next turn, that high COG has to be swung back a lot further so on fast left-rights, its hard work. After a fast run thru Deal's Gap I've been sweating...but you'd know all about sweat out your way wouldn't you Joel :-).
Dec 15th, 2006 2:09 am
kdog Isn't the reason that the LT handles so well at high speeds because of the high center of gravity? Bikes have to lean in order to work. They're not like go-carts. If the center of gravity is too low, it seems like the bike would resist leaning. And with the COG way up high, it's almost like power steering. That high mass helps you go into the turn.

That's my story, and I'm sticking to it.

-joel
Dec 14th, 2006 10:40 pm
petepeterson Jeeeezzz!!!

With so many hero's on here posting, and yet its so easy as to why some LT's are top heavy,,,,, Their riders have short legs ...Pete
Dec 14th, 2006 1:06 pm
mikeinpgh
Quote:
Originally Posted by UncleRock
Where the weight is located
Rock
and gravity ;D
Dec 14th, 2006 9:04 am
UncleRock Where the weight is located
Rock
Dec 14th, 2006 1:34 am
cyclecamper There are bad things about the weight being so high.

Mostly, when you initiate a turn you need to countersteer and the bike rolls over centered around the axis line running from front to back thru the center of mass. When that center of mass line is high, that rotate around it associated with the initiation-countersteer means the tire patch moves far outside to achieve the same lean angle. Well, really you have to steer the tire patch farther outside to get the bike to lean...and the bike dips down more...

In practical terms, we all just learn to plan ahead.

But if a real newby enters a decreasing-radius turn too hot unfamiliar with an LT and waits too late to immediately countersteer hard, he may find himself nearing the edge of available pavement and unable to counterteer and roll to initiate further tightening of his turn without running off the outside of the turn. We learn to foresee that and act sooner.
Dec 14th, 2006 1:25 am
zippy_gg
Quote:
Originally Posted by cyclecamper
The topcase is really heavy. The black padding in unnecessary weight. Vanity mirror and its frame. Good speakers require heavy magnets, and to be useful they must be mounted very high. The LT topcase is double-wall. Even the latch machanism is heavy.

The electirc windshield is really nice. But it means the shield must be self-supporting from the pivot mounts so the shield itsel fi s heavier than most. And the motor mechanism is mounted very high.

The front speakers need large magnets and are mounted pretty high too.

The Becker radio head unit is mounted very high. And though the Becker radio itself could be anywhere BMW decided to put it very high too.

The passenger seat is really high.

The alternator is very high.

The LT telelever has lots of overlap, but the lowers are also very long and go very high. The front A-arm and bearings is a relatively high steel structure.

Mirrors are nice and large, also pretty heavy.

When Gold Wings used to have log tiller handlebars like the LT, theirs were aluminum. Our center bars are heavy large-diameter pipe with smaller-diameter ends so the BMW switchpod/master cyls fit.

While other telelever fronts have a ball joint at the triple-clamp, the LT is nice in that the tiller bars don't dip or rotate with bumps, but the LT is the only telelever with a set of preloaded bearings at the triple clamp, weight up high, and the front shock & spring is very high compared to a more normal fork.

The steel pipes inside the tip-over wings are kinda high.

But the fuel tank is enormous and though they tried to drape it over the frame, it's heavy and really heavy when full, and pretty high.

The BC-3, Cb, etc, is pretty high.
Small wonder some parts get a nosebleed!!!
Dec 14th, 2006 1:12 am
cyclecamper The topcase is really heavy. The black padding in unnecessary weight. Vanity mirror and its frame. Good speakers require heavy magnets, and to be useful they must be mounted very high. The LT topcase is double-wall. Even the latch machanism is heavy.

The electirc windshield is really nice. But it means the shield must be self-supporting from the pivot mounts so the shield itsel fi s heavier than most. And the motor mechanism is mounted very high.

The front speakers need large magnets and are mounted pretty high too.

The Becker radio head unit is mounted very high. And though the Becker radio itself could be anywhere BMW decided to put it very high too.

The passenger seat is really high.

The alternator is very high.

The LT telelever has lots of overlap, but the lowers are also very long and go very high. The front A-arm and bearings is a relatively high steel structure.

Mirrors are nice and large, also pretty heavy.

When Gold Wings used to have log tiller handlebars like the LT, theirs were aluminum. Our center bars are heavy large-diameter pipe with smaller-diameter ends so the BMW switchpod/master cyls fit.

While other telelever fronts have a ball joint at the triple-clamp, the LT is nice in that the tiller bars don't dip or rotate with bumps, but the LT is the only telelever with a set of preloaded bearings at the triple clamp, weight up high, and the front shock & spring is very high compared to a more normal fork.

The steel pipes inside the tip-over wings are kinda high.

But the fuel tank is enormous and though they tried to drape it over the frame, it's heavy and really heavy when full, and pretty high.

The BC-3, Cb, etc, is pretty high.
Dec 13th, 2006 7:11 pm
Johnson
Quote:
Originally Posted by dshealey
I know that, still don't know what you meant in the previous post, about "jumping all over the place".

Everyone pretty much agrees that most of the weight of the LT is carried much higher than on cruisers. Nothing new there, very well known and understood. Anyone who has ever had the fairings off an LT would have to be brain dead not to easily see that.

The title of the start of this thread is kinda strange, what causes a high center of gravity is weight centered higher. Kinda basic.
Dave, 32 posts to tell billy that the engine is (not) low enough. Thats what I meant about jumping all over the place.
Dec 13th, 2006 5:43 pm
Billy Thanks for the good advice. I've obviously been using the rear brake too much.
Dec 13th, 2006 11:38 am
SmokinJoe
14 bikes, 1 LT?

[QUOTE=Billy]I have used the "Ride Like a Pro" video by Jerry Palladino for years with all mu Harleys. It doesn't seem to work as well on the LT. QUOTE]

Billy,

You’ve owned many bikes other than an LT. You will be a pro if you practice 'slow school' maneuvers on the ‘none-like-it’ LT every chance you get.

Last month a Motor Officer did a demonstration on the access road at the S. FL dealership (on a K1200).
One disbelieving LT owner asked if the Motor Cop could do it on an LT.


He took the guys 2007 Black LT AND HIS WIFE (as passenger) and completed tight circles both ways, figure 8’s and ABS engagement on the 18-20 foot wide access road with 2 feet on each side to spare!

He said his trick on the LT was trying to remember to use the rear brake as little as possible and to rely on the clutch. This advice helped me.

Also, I drive (literally) my SO crazy by zipping into ANY empty parking lot doing circles, 8’s, and locked turn starts and I now welcome making these necessary maneuvers normally in parking lots.

BTW when I do the tight circle practice she ALWAYS threatens to hurl!
Dec 13th, 2006 6:09 am
murray
32 Lbs !!

I know the tour pack is heavy and was curious to how heavy. Can you say 32 LBS ! WOW !
Dec 13th, 2006 2:50 am
meese
Quote:
Originally Posted by russte
Okay, come on over stud, I’ll even put a new set of tires on sweetheart for ya, on one condition. When you bring her back they have to be worn out!!!!!!!
I wore a set of tires off my '99 in two weeks riding around Germany then back to Wales. It would have been quicker but we had to do some sightseeing. It really freaked out the local tire shop when I came back and told them their tires must have been defective because they were all gone already.
Dec 12th, 2006 11:41 pm
dshealey
Quote:
Originally Posted by Johnson
Hi Dave, draw a line from the rear axle to the front axle, The 1200LT crank and most related part are above that line.
I know that, still don't know what you meant in the previous post, about "jumping all over the place".

Everyone pretty much agrees that most of the weight of the LT is carried much higher than on cruisers. Nothing new there, very well known and understood. Anyone who has ever had the fairings off an LT would have to be brain dead not to easily see that.

The title of the start of this thread is kinda strange, what causes a high center of gravity is weight centered higher. Kinda basic.
Dec 12th, 2006 10:49 pm
Johnson
Quote:
Originally Posted by dshealey
I have no idea what you are trying to say with that comment. Explain please?
Hi Dave, draw a line from the rear axle to the front axle, The 1200LT crank and most related part are above that line.
Dec 12th, 2006 10:06 pm
dshealey
Quote:
Originally Posted by Johnson
You guys jump all over the place with one. --------------.
I have no idea what you are trying to say with that comment. Explain please?
Dec 12th, 2006 8:25 pm
Johnson
High center of gravity

You guys jump all over the place with one. The mass of the flat four engine is above the axles, HDs and most english bikes the mass is below the axles. Just my two bits.
Dec 12th, 2006 6:30 pm
Billy I am sooooooooooo happy about anything that lowers the COG!! Also, I installed a ballistic fabric briefcase (weighs maybe one half pound) instead of a Fort Worth Rack. Doesn't look quite as cool but the storage for cd's etc. is very convenient and it covers the plastic panel.
Dec 12th, 2006 4:42 pm
dshealey
Quote:
Originally Posted by Billy
I just removed the topcase and it seems to make a noticeable difference. I don't know if it contributes to the high center of gravity or not but the whole bike feels better without it.
Any weight added to the bike above the C/G that existed before adding it will raise the C/G from it's previous position. The top box is certainly above the C/G, so that definitely raises it when installed, lowers it when removed.
Dec 12th, 2006 4:34 pm
messenger13
Quote:
Originally Posted by avonfloater
What did BMW do to the 05s to improve the low speed handling?
They changed the rake a tad. I've ridden a few '05s, and I couldn't tell the difference. Then again, I didn't have any issues with my '02 at low speeds either.
Dec 12th, 2006 4:11 pm
avonfloater I noticed in one of these posts the following -

"It's top heavy, but nothing a seasoned rider should worry about, low speed handling is much improved on the '05s "

What did BMW do to the 05s to improve the low speed handling?

Denny
Dec 12th, 2006 1:48 pm
Billy I just removed the topcase and it seems to make a noticeable difference. I don't know if it contributes to the high center of gravity or not but the whole bike feels better without it.
Dec 12th, 2006 11:53 am
zippy_gg
Quote:
Originally Posted by Billy
I love my new LT but the high center of gravity takes some getting used to. The handling is superior to any bike I have owned ( I have had 14). The engine seems low enough not to do it. Is it the topcase? If so, I plan on removing it.
I think it has to do with fat riders!!!
Now, if you are going to be fat and ride the LT be sure to have a big butt rather than growing boobs as this would definitely relocate the COG even higher. Simple physics at work!
So... what's for dinner???
Dec 12th, 2006 11:42 am
messenger13
Quote:
Originally Posted by russte
Okay, come on over stud, I’ll even put a new set of tires on sweetheart for ya, on one condition. When you bring her back they have to be worn out!!!!!!!
Aren't you supposed to talk dirty to me AFTER you pump me full of that good German beer!!!
Dec 12th, 2006 11:35 am
russte Okay, come on over stud, I’ll even put a new set of tires on sweetheart for ya, on one condition. When you bring her back they have to be worn out!!!!!!!



Quote:
Originally Posted by messenger13
I'll fix that little issue when I come over there
Dec 12th, 2006 11:07 am
messenger13
Quote:
Originally Posted by russte
Hey!!! I resemble that remark…. Sh*t head………. .
I'll fix that little issue when I come over there and teach you how to ride. No problem!
Dec 12th, 2006 10:57 am
russte Hey!!! I resemble that remark…. Sh*t head………. .


Quote:
Originally Posted by messenger13
Besides...Chicken Strips are for posers.
Dec 12th, 2006 10:53 am
dshealey
Quote:
Originally Posted by Bandit
i believe the main cause is the front suspension, which does not compress when you squeeze the brakes. this gives the bike a "wooden" feel at slow, parking lot speeds, and makes it feel tipsy (at least to me) before you get used to it. that, combined with the high seat.
That is an affect of high C/G, not a cause. High C/G is strictly physics of having more weight high up than many other bikes. The heaviest part of the engines for instance is the crankshaft/flywheel assy, which is very low in big V-twins, much higher in the LT. Also on the LT that big aluminum frame casting is very high, most of it above the engine, where on the Harleys most of the framework is low, with just a little pipework above the engine.

It is not all bad though, as I found after getting back into riding on my son in law's harley, then buying an LT. The Harley was worse in gusty cross winds than the LT, which really surprised me due to all the "sail" surface on the LT. The Harley tried to go in the direction of the gust wind, the LT actually self corrected INTO the wind. Found an article that explained it. If the "Center of Area" that the wind is hitting is above the "Center of Mass" (C/G). then the bike will be leaned away from the wind, as on the Harley, shich is the way you do not want to go. When the Center of Area is below the Center of Mass, then the wind affect will partially lean the bike into the wind, as on the LT.

I had to ride a LOT in strong gusty winds here in SoCal due to the preponderance of mountain roads and "wind tunnel" passes and found the LT to be darned good, and if you just lightly correct and do not white knuckle the bars the bike practically takes care of the gusts itself. The Harley had to be manhandled in gusts.
Dec 12th, 2006 9:46 am
Bandit i believe the main cause is the front suspension, which does not compress when you squeeze the brakes. this gives the bike a "wooden" feel at slow, parking lot speeds, and makes it feel tipsy (at least to me) before you get used to it. that, combined with the high seat.
Dec 12th, 2006 9:35 am
Billy Ultra LT,

I am so glad I now have reason the Palladino technique didn't work well. I guess I am destined to wider radius turns at slow speed.
Dec 12th, 2006 9:03 am
jrlakin I had always ridden Harley's until I got my LT last November. Frankly, I don't think the LT handles all that badly at low speeds. It is true it takes a bit more turn radius and it is a little worse at the lower speeds, but I have been very happy with the low speed handling. Maybe my Ultra Classic was good training. Actually, where I do think my Harley does have it over my LT, is out cruising on the Interstate. I think overall the Harley feels like is has better stability, less buffetting in the wind and from the turbulance from Semi's, and I like the position of the mirrors on it better. Having said that, I hardly ever ride my Harley anymore, so there is no question as to which is more fun to ride, and which one I like better. jrlakin
Dec 12th, 2006 8:20 am
UltraLT
Ride Like a Pro

I went to FL last March to take Jerry Palidino's 4 hour course, which is the same as his video. His technique does not work well at all on LT's due to the linked braking. No matter how softly I modulated the rear brake, at some point the front brakes came on and in a slow lean, you know what that means. Only cost me $100+ to replace lower cowling where the Jpegs punctured it.

He took my bike and had difficulty himself, missing a few gates. At the end of the course, he told me that BMW tell him the LT could run his course in 2nd gear and no brakes. Now that, I want to see.

Ultra LT

Riding is life. All else is just waiting.
Dec 12th, 2006 5:36 am
dronning The engine sits higher than you think - it only takes a few inches couple that with the high fuel tank, trunk, seat etc..

Take a look at the rollover (roll your mouse over the nice LT pic) located just after the farkle list:
http://everythingsop.com/Joomla/content/view/3/2/

Dave

ps I should point out the naked pic is backwards but that is the only way I could do this I didn't have 2 shots from the same side.
Dec 12th, 2006 1:33 am
JDW I have to think that the heaviest single part of the bike is the engine. My guess is that the engine is relatively high in the frame which probably contributes to it's very good high speed handling. I tried to explain to my son how top heavy it is before he took it for a ride and I think he thought I was exagerating. He dropped it before he even got it into gear. He said after ward that now he knows why I am so cautious with it at slow speed. All in all it is a great bike but if there was a fix for it being so top heavy I for one would probably use it. However I do know that the more I practice slow speed manuvers the easier it is. I tip my hat to the engineers who designed the wings that protect the bike from damage when it is dropped. However the fact that they are on the bike should tell us something.
Dec 11th, 2006 10:37 pm
meese Removing the top case takes under 10 minutes and makes a noticeable difference.
Dec 11th, 2006 9:32 pm
messenger13 Another reason yet mentioned is that the LT has a better available lean-angle than any cruiser out there, and even the GoldWing. And improved lean angle is the result of moving things UP! Thus, the COG suffers. But I'll take available lean-angle over a lower COG anyday.

Besides...Chicken Strips are for posers.
Dec 11th, 2006 9:08 pm
rkirker
Earth

Why the spin of the Earth Billy
Bill Nye the science guy told me

I crack myself up !!
sorry just could not help but be a smart arse

Seriously:
I think it is the high seat and Big tank


Quote:
Originally Posted by Billy
I love my new LT but the high center of gravity takes some getting used to. The handling is superior to any bike I have owned ( I have had 14). The engine seems low enough not to do it. Is it the topcase? If so, I plan on removing it.
Dec 11th, 2006 8:20 pm
dshealey
Quote:
Originally Posted by Billy
I have used the "Ride Like a Pro" video by Jerry Palladino for years with all mu Harleys. Using the rear brake only and feathering the clutch allows total control of the heaviest Harley at 1MPH. It doesn't seem to work as well on the LT. I won't get rid of the LT because it enables me to ride in the cold with out a problem, which the Harleys never did. The handling is also far superior to any of my Harleys.
It is much like aircraft. The competition Aerobatic pilots set up their planes to a point that a non aerobatic trained pilot would think they are just barely controlable, and would likely get in trouble fast trying to fly one.

If you want a bike to handle the twisties really good, then it won't be as "stable" in a cruising mode. The Harleys are big, heavy, but stable bikes, but that stability is against them when the going gets twisty, needing to be manhandled through the turns. The LT is set up to handle very well for a big bike, but you pay in the slow speed stability, meaning that it is almost effortless at speed, but you have to be ready to manhandle it a bit in the parking lots. Pretty hard to have both. Personally, I will trade the little time in the parking lots for great handling the 98% of the time when I am moving faster. Also, the LT carries a lot of weight up high, the engine CG is higher than the Harley, the Tank is higher, big heavy aluminum casting for a main frame, also high, above the engine.
Dec 11th, 2006 7:23 pm
Billy I have used the "Ride Like a Pro" video by Jerry Palladino for years with all mu Harleys. Using the rear brake only and feathering the clutch allows total control of the heaviest Harley at 1MPH. It doesn't seem to work as well on the LT. I won't get rid of the LT because it enables me to ride in the cold with out a problem, which the Harleys never did. The handling is also far superior to any of my Harleys.
Dec 11th, 2006 7:15 pm
donsobeck Billy: If you are talking stopped and slow speed turning its the geometry of the front suspension that makes the bike want to fall over. As the handle bars are turned the weight of the bike is moved off the center line and now its hard to hold up.

DON
Dec 11th, 2006 7:10 pm
BLBantz The seat is higher than most bikes, so the rider is higher as well. The top case is higher and when loaded with luggage and a bag on the top rack it adds considerable top weight. The gas tank is pretty high, etc. After two and a half years and 36000 miles I think I can say that the LT handles better than most others at speed, but be careful at slow speeds. That said, I wouldn't go back to the cruisers for anything. I accept the challenges and ride the..well I ride it alot.
Dec 11th, 2006 6:55 pm
Billy
What Causes The High Center of Gravity?

I love my new LT but the high center of gravity takes some getting used to. The handling is superior to any bike I have owned ( I have had 14). The engine seems low enough not to do it. Is it the topcase? If so, I plan on removing it.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

 
For the best viewing experience please update your browser to Google Chrome