Chassis balance

[Guest ratchethack]

As discussed many times previously, one o' the V11's several Achilles heels, o' which it would seem to have quite a few more than it has feet, is its fundamental rearward weight bias, which -- let's face it, Gents -- on top o' the overly-ample porcine poundage, short swing-arm, driveshaft, and 20 lb. bevel drive hub, puts some additional tough hedgerows around what's possible to achieve handling-wise.

 

T'other day it suddenly sprang upon me that I just had to know how bad it actually is. So with my trusty bathroom scale and a pile o' blocks, I repaired to the moto garage, overcome with inspiration and renewed intent on expanding my Guzzi knowledge.

 

Measurements were made one wheel at a time, with wheels blocked up even and level.

 

Here's wot I found:

 

DISCLAIMER: I weigh 180 lbs without riding gear. Measurements were made without riding gear. My Guzzi is a slightly modified 2000 Sport. The most significant mods likely to affect front-rear weight bias are replacement of stock mufflers with FBF carbons, and a list o' such trifling matters as the addition of a Stucchi flyscreen, Throttlemeister 14 oz. bar-ends, a smattering of relays and heavy gauge wire, a set o' Fiamm Highway Blaster horns, a Stucchi crossover, Roper plate, etc. The latter items I consider negligible to the exercise. Measurements were made with a half-tank of fuel. Laden readings were taken in riding position, as would be the case when taking sag measurements.

 

534 lbs. = unladen

714 lbs. = laden

 

47/53 = F/R % unladen bias

42/58 = F/R % laden bias

 

This is actually not as bad as I had expected.

 

Coupla observations:

 

While this aspect of the Guzzi design alone, IMHO, takes the Guzzi Sport OUT of the category of modern, nimble-handling Sport machines of today, (some would say it's already pretty far out) It's not that far out.

 

I'd expect that raising the bars would shift the laden weight bias rearward - possibly a considerable amount.

 

I'd expect that heavier riders would shift the weight bias further rearward, and lighter riders would shift the bias forward.

 

BAA, TJM, & YMMV

[dlaing]

Thanks for the research

That is a little surpising.

How full was the fuel tank.

Can you give us an idea of where you sit in the saddle?

Tail bone against rear cowling?

Crotch against tank?

somewhere inbetween?

Probably like most people, I find the bike handles better when I shift my weight forward.

Also FWIW, when shifted rearward, the bumps in the road are brutal.

[Dan M]

That's interesting. I'd assume that the LeMans (long frame) is slightly less rear biased with the weight of the faring and it's ancillaries, however that is probably given up when laden due to the higher bars...

I'm the same weight as you and tend to crowd the tank during "spirited" riding, getting my weight as forward as possible. Still, the thing is a bit of a lump.

I have a feeling though, now that I'm armed with this knowledge, the next time I take the MG out it will handle exactly the same.

[Martin Barrett]

Thanks for the research

That is a little surpising.

How full was the fuel tank.

Can you give us an idea of where you sit in the saddle?

Tail bone against rear cowling?

Crotch against tank?

somewhere inbetween?

Probably like most people, I find the bike handles better when I shift my weight forward.

Also FWIW, when shifted rearward, the bumps in the road are brutal.

 

Being rather equine like I do both simultaneously (in my dreams)

[dlaing]

Being rather equine like I do both simultaneously (in my dreams)

You have got the spirit of French Bob's Rooster

[Guest ratchethack]

How full was the fuel tank.

Can you give us an idea of where you sit in the saddle?

Dave, the tank was half full, as noted.

 

This exercise didn't change my riding technique, which I developed years back on my first foray into the local mountains. Back then I discovered immediately that the bike will tend to "push" considerably unless I get way up over the front wheel. This has been true in my case with each of I think 4 different front tires now, regardless of stock or now fully matched springs and custom suspension, and regardless of where I've got the fork stanchion height set, though raising the fork spring rate by 50% and then dropping the triples to compensate for rake, trail, and ride height changes lessened the tendency to "push". I flex my elbows quite a bit and push up hard against the tank pad, and this makes a HUGE improvement to handling the way I ride. I find that it feels SO much more neutral this way that not doing it gives it relatively awkward and vague tracking, especially when hard over and close to touching the hard parts down. Without getting way up forward I wouldn't hardly notice how much I LOVE my Z6's. On the slab I can relax with arms less flexed and will push back to the cowl bum stop to get down further behind the flyscreen at 80-90 mph. As a dedicated Road Geez , none o' this is any basis whatsoever for claims at being a talented rider, but it sure helps in the "smooth" and enjoyment departments.

 

Makes me wonder how much better it might be if it were closer to 50/50 than 42/58. It also makes me wonder wot Guzzi was able to achieve with the MGS0-1, Griso, Breva, new Sport 1200, etc.

[Guest ratchethack]

Good work ratchet but...

You may need to measure the relative axle centerlines and apply calculus in order to avoid having your methods scrutinized negatively. Not to mention the use of bathroom scales. I am sure this work would garner much feedback amongst the Johnny come lately Duc posers .

Now Gary, leave us not poke fun here. This is serious stuff. As we all know from observing the depth of knowledge and wisdom demonstrated on this Forum, certain Ducatisti hereabouts are of necessity quite accomplished mathematicians, as well as consummate readers of most extraordinarily prodigious comprehension, not to mention True Masters of cleverness.

 

Whilst wetting my whistle at a local watering hole last evening, in order to understand more about how accomplished Ducatisti might require Calculus to torque bevel heads, I consulted with a member of our local Euro-Moto Breakfast Club, himself one of hundreds of local Ducatisti very much "in the know" on these matters.

 

I asked him what level of mastery of Calculus was generally required to torque the heads on a bevel head.

 

In reply to my question, this is what he said -- I got it down word for word:

 

"It is well-known that the interaction between standard (classical or intuitionistic) logic and combinatory logic is problematic. Yet applicative theories, i.e. first order theories of self-applicable operations based on combinatory logic, have been extensively investigated in the context of the foundations of differential geometry. We survey consistency and conservativeness results about applicative theories involving (forms of) the axiom of choice, extensionality, Church's thesis and the enumeration axiom. As to the methods, we mainly apply constructive tools (forcing, realizability, cut elimination). We next explore Differential Geometry, General Relativity, and solutions of linear and nonlinear ordinary differential equations. Methods of Frobenius, classification of singularities. Integral representation of solutions. Treatment of the Bessel, Hermite, Legendre, hypergeometric, and Mathieu equations. Asymptotic methods including the WBK and saddle point techniques. Treatment of nonlinear autonomous equations. Phase plane trajectories and limit cycles. Thomas-Fermi, Emden, and van der Pol equations. Partial differential equations of first and second order. Hyperbolic, parabolic, and elliptic equations including the wave, diffusion, and Laplace equations. Integral and similiarity transforms. Boundary value problems of the Dirichlet and Neumann type. Green's functions, conformal mapping techniques, and spherical harmonics. Poison, Helmholtz, and Schroedinger equations. Integral equations of Volterra and Fredholm. Inversion of self-adjoint operators via Green's functions. Hilbert-Schmidt theory and the bilinear formula. The calculus of variations. Geodesics, Euler-Lagrange equation and the brachistochrone problem. Variational treatment of Sturm-Liouville problems. Fermat's principle. Finite-difference calculus; interpolation and extrapolation; roots of equations; solution of algebraic equations; eigenvalue problems; least-squares method; quadrature formulas; numerical solution of ordinary differential equations; methods of weighted residuals. Finite-difference methods for parabolic, elliptic, and hyperbolic partial differential equations."

 

It was at that point that my Ducatisti Pal was interrupted. It seems that after overhearing this, someone at the next table had picked up a chair. When I saw it raised above head level out o' the corner o' my eye, that's when I made my dive for the door. I never looked back. From the racket o' the ensuing commotion over my shoulder, I'd made it out just in time.

 

I reckon torquing a bevel head's not for the faint o' heart. . . . . .

 

[badmotogoozer]

You certainly are kindred spirits.

 

No issues with the math here. Measuring both wheels in the same manner and expressing the results as a percent bias negates any measurement errors that may be involved.

 

Rj

[jrt]

I put higher bars (2, 3" maybe) on my Sport- it definitely biases the weight aft.

 

An easy way to compensate for this is to fill your front tire with Argon or Radon and the rear tire with Hydrogen or Helium. I prefer radon for the front because it's so common in my geographic location.

[badmotogoozer]

 

Thomas Edison once asked Nikolai Tesla to tell him the volume of his light bulb's globe. When he came back an hour later Tesla was still measuring and calculating using complex formulae. Edison filled the globe with water and measured the volume. Tesla finished his calculations hours later and proclaimed Edison's number was wrong.

 

They weren't measured in the same manner if the axles were ar different relative levels.

 

Ratch has stated that they WERE at the same level.

 

And this little Edison - Tesla fairly tale holds as much water as the Washington - cherry tree tale.

 

Hours to calculate the volume of a light bulb? Give me a break! This is just another fairy tale for the American public which praises the genius of the American inventor and mocks the immigrant inventor.

 

But you are right, Gary, we should abandon mathematics entirely (vague subject that it is ) and base engineering on your personal experiences.

 

Rj

[Guest Gary Cheek]

Ratch has stated that they WERE at the same level.

 

And this little Edison - Tesla fairly tale holds as much water as the Washington - cherry tree tale.

 

Hours to calculate the volume of a light bulb? Give me a break! This is just another fairy tale for the American public which praises the genius of the American inventor and mocks the immigrant inventor.

 

But you are right, Gary, we should abandon mathematics entirely (vague subject that it is ) and base engineering on your personal experiences.

 

Rj

 

 

 

 

Tesla was a great scientist, Edison was the son of a poor IMMIGRANT .

Tesla did at one time work for Edison. The son of a poor immigrant with a third grade eduaction at least knew talent when he saw it. He also had the resources to hire Tesla.

 

But then again, I was just ribbing

 

By "at the same height",just how was that established? Surely if we can question the alignment of a machine made 40 mm extension and the effect of a 150mm Z axis spacer the relative height in this application could be called into play. If you can rib you can expect to be ribbed.

Abandon mathematics? Wrong, goozer. No one proposed abandonment of mathematics in engineering. Just that there are times when the practical application in the field puts the theoretical in the back seat. The methods are not my experience , most of them are common,accepted PRACTICE. That would be your leap not mine, thank you.

Getting a little touchy? So we should base our view of history on your personal experience with the events? Or just your anti American bigotry? The "Fairy tale" was offered as a parable. It is a very common situation typical of many folks experience with engineers. We don't always have to take the time to prove mathematically operations that are more easily proven empirically. Often the math takes shortcuts or has errors built in by supposition. For all the factors involved torquing your bevel head the simple verification of the actual set up by actually measuring the applied torque through the set-up will most likely give a more accurate real world torque than the math modeled theoretical example.

 

Just ribbing

[Paul Minnaert]

Well with some grinding and welding the weight balance can be moved forward. Extend the swingarm, and cut a piece out of the spine. At the same time the head angle can be made a bit more modern. It all is some work, but doesn't cost an arm and a leg.

[badmotogoozer]

" For all the factors involved torquing your bevel head the simple verification of the actual set up by actually measuring the applied torque through the set-up will most likely give a more accurate real world torque than the math modeled theoretical example." - Gary Cheek

 

Which is exactly what I ended up doing, not wanting to do the math and tired of the listers scrapping it out while I waited for feedback.

 

You'll have to try a lot harder to get me hot - I LOVE stirring the shite, and I'll happily do so even if I know I'm wrong!

 

I am offended by your suggestion that I am anti-American. I most certainly am not, nor am I pro-American. There is a difference (indifference). Some of my closest friends are American. This is your only comment I've taken seriously.

 

Rj

[Guest Gary Cheek]

Actually your anti American statement was the only one I cam close to taking seriously. I wasn't however offended . A statement like that is more reflective of the person who makes it. The parable is about practical vs theoretical. The national origin of the players has nothing to do with the intent.

 

Your statement reveals an obvious bigotry. Perhaps you will deal with it now. The American public I know would rather not belittle. Especially their immigrant ancestors.

[badmotogoozer]

And in the case of the torque - I am. If not, well then I better quit the job I've had for the last 12 years as I'm certainly not qualified for it. The longer the extension and the farther from straight, the greater the error in the torque measurement. That I will stand by.

 

I don't believe I've said anything anti-American. The USA has a long history of treating immigrants as second class citizens. One only has to cross the border with someone who isn't Canadian or American (in my case my ex-girl) to know the sentiment persists. *edit* I shouldn't single out the US on this, though. Canada does the same in many ways. It is a shame that someone with a Master's degree and 15 yrs experience running a power plant in the Phillipines now has to clean my office every day as punnishment for moving to this country.

 

Enjoy the weekend - I've got a life to go live...

 

Rj