Better "flickability"

[Guest ratchethack]

Just a coupla comments here on steering damping.

 

FWIW, I hope no one will get upset or perceive a personal attack here? Such is not my intent. I sincerely hope that no one is offended or somehow threatened by this.

 

It's just an observation based on 40 years of riding 12 motorcycles. For starters, I'd never ride a moto of any kind with a binding or intermittent steering damper, any more than I'd ride with a spike sticking out of a tire!

 

Steering dampers are a vital component of most road-going sporting motorcycles for a reason. They ARE NOT for the purpose of providing resistance to bar input! If there were no valid reason for them, the expense of adding them would be happily obviated by bean-counters. This is one of the few common moto components where I believe a strong correlation exists between function on both road and track. Though there are undoubtedly exceptions to this, I have never seen a competitively campaigned ROAD racing moto without a functional steering damper that's depended upon to a high degree by the rider to function as designed.

 

I've seen a mighty heap o' improperly used dampers, mostly "permanently" cranked back to "zero". With no damping fluid circulating, my theory on the most common cause of failure of steering dampers is that the seals eventually dry up, leak oil, and the next time the thing is dialed-up, it either squirts the rest of its oil out past the shrunken/hard/cracked seals, and/or doesn't work, and/or worse, it works intermittently -- which is to say very dangerously.

 

Properly used, steering dampers provide resistance to rapid movements and oscillations of the front wheel AT SPEED ONLY -- NOT at parking lot speed, where the common rank Newb tends to decide he doesn't like it dialed-in! There is a reason they are provided with a handy adjustment knob. This is so they can be adjusted ON THE FLY. IMHO, much confusion and misunderstanding persists.

 

Steering dampers function twofold:

 

1. As an "insurance policy" to reduce the onset of cyclical conditions that very rapidly escalate into the dreaded "tank-slapper", and ALSO to reduce the onset of the related-but-not-at-all-the-same "high speed weave", both of which can (and do) happen to nearly every conceivable kind of motorcycle ever built, under certain conditions. YES! Too much damping can CAUSE high-speed weave!

 

2. To improve the control, and therefore the feel of the motorcycle when encountering uneven surfaces and in negotiating limitless kinds of "transitions" that could induce rapid fork movement (see #1 above). Yes, I've had both happen to me on both pavement and off-road, on several occasions on several moto's when not enough, or no steering damping was dialed-in.

 

CAUTION! This IS NOT a "fail-safe" control! Like the throttle, a steering damper can be dangerous when not used properly!!! UNLIKE the throttle, it's important to understand that this IS NOT a "dead man's" control -- that is, it DOES NOT back itself off automatically when released! Also, used properly, it's a speed-dependent control, not a "set it and forget it" device like suspension damping!!! Best use all moto controls judiciously at all times!

 

I have habitually ridden with my steering damper on relatively low damping full-time, on every moto I've owned that had one installed, and I typically crank it up on the fly at higher speeds, exactly as they are intended to be used. When it's not on, or not cranked up high enough, the Guzzi feels slightly wierd and a tad skittish to me. Yes, I've owned many, and even now own a moto without a steering damper. It's a big trailie, with a whopping big fork rake, and it's capable of intentional rapid fork steering movement in the soft stuff, not remotely approachable on pavement. Nevertheless, I'd like to add a top-mounted axial-type steering damper to this bike for high-speed work, and likely will.

 

YES! If you forget you've got the steering damper cranked up for 100 mph sweepers and suddenly try to negotiate a parking-lot maneuver, you could very well drop the bike at 2 mph! If you can't remember to crank it back in time when you slow down, it is UNSAFE for you to use! Best not crank it up as much in the first place, or simply do without!

 

I put a "projection" on the adjustment knob of mine so I can feel where it's set without taking my eyes off the road, which I find very useful. I seldom forget to back it off when needed, but when I do forget (it happens), I find that quickly whipping it back down is reflexive, well established in muscle memory, and safe. I've never dropped any bike by using the steering damper.

 

I've observed that many riders feel resistance to the turning of the fork with a steering damped bike when parked or at parking-lot speed, and instantly conclude from this that they don't want to feel this kind of resistance to steering on the road. SURPRISE! At road speeds, they won't -- and can't! In my experience, there are NO conditions of operating a road motorcycle at speed on any kind of road (one of my favorites being local mountains), where a fork may be turned fast enough in normal turning of the bars and fork to exhibit anything approaching the kind of resistance encountered when "feeling it" static or at parking-lot speeds. At road speeds, it's simply not possible to turn the fork fast enough to feel much of any direct damping resistance to bar input at all, unless you've got a grossly out of proportion, and prohibitive degree of damping cranked-in for the speed you're riding.

 

I've concluded that many have a predisposition against using a steering damper based on the psychological (and entirely incorrect) basis of equating static to real-world dynamic effects of the damper when properly used.

 

BAA, TJM & while YMMV, I will certainly stand by this observation, as I always have.

[dlaing]

snip

But I must add, if your damper is defective, by all means take it off and order one of them nice HyperPro ones.

[Ouiji Veck]

Very well said Iyegor

[GuzziMoto]

Sorry Ratchet, but you are deadnut wrong on that one. Most motorcycles do not have nor require a steering damper. Those that do have one either need it because of aggressive steering geometry(which our Guzzi's do not have. they steer pretty slow), or they have one due to fashion considerations(which is probably how Guzzi's end up with one.). If you like having one, that's fine. But a modern Guzzi does not need one to be a safe and happy motorcycle.

[Phil A]

I'm with you Guzzimoto,

 

Go on a ferry trip and take steering damper with you.....

 

When you get to the centre of the channel, go to the rear of the ferry and throw it as far as you can.....

 

If your Guzzi needs a steering damper then its not set up properly.

 

 

 

Phil A.

[Slavomir Musilek (R.I.P.)]

hm... I must point that on Czech roads, steering damper is very very very needed

[tripletom]

If its anything like the damper that came off my wifes bike(for same reasons) full soft still had too much resistence. Plus hers would bind, resisting movement, and then let go cuasing the bike to weave. Pulled it off and bike 100% better. A bike with that kind of geometry does not need a steering damper anyway. It can only be a bad thing.

 

The Ohlins steering damper on mine wasn't binding in the damper itself. When I picked the bike up it was wound 2 clicks off full-on and was horrible. I wound it all the way off but was still getting a weave at 95 up and the bike wasn't holding it's line through corners. I removed the damper last night and the bike feels oh so much better. 120mph (on private roads) and not a hint of a weave.

However; the damper I don't believe is wholly to blame, the rose (heim) joints were very dry. The frame mounting one in fact refused to budge so is now soaking in plus-gas. There was also a large washer under the yoke mounting joint which was restricting rotation there. If the bike gives me a few slappers then I may re-fit the damper, but for now it's staying off.

[GuzziMoto]

Just for anybody who cares, I made a mistake. I confused two seperate steering damper situations. The one that was binding was not the one that came off my wifes V11. The one that came off her V11 was fine, it just made the bike handle poorly. It was a different bike that had the damper that was binding.

If anyone feels like a steering damper makes their bike handle better, that's fine. Run a damper. But please don't preach to the rest of us saying that it's a important component that we are crazy to remove. Feel is subjective, and if you like the way a damper feels, great. But some of us prefer the lighter steering and better feedback that you get without the damper. Feel free to try both ways than decide for yourself which way you prefer, just don't go on and on about why your way is right and the other way is wrong.

[dlaing]

I have had a near tank slapper after getting airborne from a dip in the road at 120 veglia MPH, and I am pretty sure the damper saved my life.

[Guest ratchethack]

Well, so much for the expressed hope of not having someone take offense and/or be threatend by straightforward observations and long-established practical wisdom. . .

 

And by all means, to each his own, it's a free world (at least in the First World), and all that. . .

 

Certainly the LMs with 26 degrees of rake and relatively long trail are slightly more stable than most other "sporting" bikes on the road today. . . Does this mean that they can't benefit at all from the use of a steering damper, and that they're equipped with them from the factory mostly as a fashion statement, as has been suggested? For those of us who're sincerely interested, leave us explore this a little further. Ignore at your own risk, but best measure that risk very carefully first. . .

 

Those of us with the "short frame" 25 degree rake bikes are in a slightly different category, but not all that different from that of the 26 degree rake LMs. Since I've set mine up closer to 24 degrees rake (still not nearly as steep as many sport bikes commonly available today), I reckon I've properly focused on steering damping more than other Guzzi riders. But IMHO, this is not to say that steering damper function somehow isn't significant enough for ALL Guzzi riders to at least understand, if not dismiss out of hand as not worthy of consideration under the notion that it's merely a useless fashion statement.

 

Though the observations in the previous post are all mine, I didn't dream up the importance of steering dampers on Guzzi's out of thin air, Gents.

 

So where, exactly, does the rubber meet the road (so to speak) on steering dampers on our Guzzi's?

 

Here's a writeup of a steering damper "impulse test" (see below) by Ed Milich at GuzziTech. I've done this test on my Guzzi many times. It illustrates very clearly and dramatically the effectiveness of steering dampers. Ed comments specifically on all "slow steering" Guzzi's. Ed's a good guy, long-time racer, machinist par excellence, and Guzzi aficionado, known to many on this Forum. Met him several times, as have many hereabouts. Ed rides an LM IV, and relates the following test to his own LeMans, which he's set up with 25 deg rake and 107 mm trail.

 

1. Yes, Ed uses a steering damper even on this stable old sled.

2. No, it's not there for cosmetic purposes.

3. No, it's not there because Ed doesn't know how to set up his suspension properly.

4. No, it's not there because there's something inherently WRONG with his LM IV's newly re-framed Tonti geometry or its legendary bank-vault torsional rigidity.

5. Yes, all V11's have the same characteristic excessive rearward weight bias as Ed's LM IV.

 

V-twin Guzzis can (and do) have a tendency to get their front end lighter than other bikes in many kinds of demanding riding, making a steering damper at least wise, and clearly advisable from a safety standpoint alone -- at least for those willing to defer to the highly qualified knowledge, experience, and understanding of the likes of Mr. Milich. Again, as has been pointed out, not everyone rides the same, nor on the same kinds of roads. No question about it, many riders will never know the difference, and many others will simply never be curious enough to give a rip. C'est la vie.

 

As Ed points out, using a steering damper can save your hide and everything in it, not to mention your Guzzi. It's the "unplanned" circumstances where it likely provides the most value. Ever have an "unplanned" circumstance develop on the road? Would anyone other than a rank Newb answer, "No"? From this perspective alone, it would seem to be cheap life, medical, and long-term health care insurance of the very best kind -- that is, the preventive kind, an ounce of prevention being worth. . . (well, you know).

 

Guzzi Practical Suspension Setup Tricks for Road Bikes: Steering Dampers

 

Ah , the lonely steering damper… It’s one of the most misunderstood components of your steering system. What the heck does it do? Do you need one if your bike doesn’t already have one? If you have one, how do you adjust the darn thing for optimum performance?

 

First of all, you need to know some background on the vibration modes of a motorcycle: specifically, wobble mode (i.e. the “tank slapper”). Wobble can be described as a self-perpetuating vibration of the front fork assembly about the axis of the steering stem. A number of variables like tires, loads, and fork geometry affect this mode. Maintaining stability while providing a quick response to steering inputs is the basic tradeoff in designing the geometry of a front end. Thus, bikes that steer more quickly are more susceptible to wobble, as they operate closer to the borderline between stability and instability of the front end. Also, wobble stability can change with speed, and load. Variables such as wind gusting, vehicle speed and wheel rotation also affect wobble, and certain combinations of these variables can cause a dramatic loss of stability.

 

The problem with wobble is that it’s a very lightly damped mode. The only physical damping comes from friction in the steering head bearings, and the hysteresis of tires and other dynamic elements. This damping is very slight, thus quick-steering bikes require the use of an external steering damper.

 

First of all, how does one determine the degree of wobble stability of a motorcycle at a specific speed and load? For this quantification, we will use our old friend the impulse test. Caution: perform this test at your own risk. I claim no responsibility for your actions. Disconnect your steering damper, or adjust it to a minimal setting. Bring your bike up to a constant speed on a straight, flat surface. To hold the speed constant, I use a throttle lock of some sort: my Lemans IV has a throttle friction screw, which works fine. With the bike moving straight ahead, and with your hands off the bars, whack one handlebar very quickly in the same plane that you would normally apply force to the handlebars to steer the bike. That is, give it a not too large, yet firm and quick input *whack* in a plane perpendicular to the steering axis. It may take some experimentation to whack it just right. You are basically exciting the wobble mode with an impulse input. If the steering borders instability, a very small steering input will produce a large wobble. If the steering is moderately stable, you may see a few oscillations before they die out entirely. If the steering is very stable, there will be no wobble at all. Note: prepare to catch the bars in case your steering is unstable! The degree at which the front-end oscillates for this test tells you your wobble stability for the test conditions. Now repeat the test. Try varying the speed in 10 MPH increments and observe how the response changes. If you normally carry a lot of load, put it all on the bike and perform the test again.

 

Why does the impulse test work? An ideal impulse input has an infinite amplitude, yet an infinitesimally small time duration. The quick “whack” to your bars approximates the impulse input. Theory dictates that an impulse input has a flat frequency response- it excites all frequencies at the same level. Associated with the wobble mode is a specific natural frequency, which is excited by the impulse. The response of the front end to this input is to oscillate at the wobble natural frequency. If this vibration mode is very stable (as it is for most Guzzis and bikes with a lot of trail for most operating conditions), the oscillations will die out on their own. If the vibration mode is marginally stable the oscillations will take a long time to dissipate. If the vibration mode is unstable the oscillations will grow until your front end oscillation hits both steering stops!

 

You may also want to perform this test while decelerating. This places additional weight on the front wheel and therefore the vibration of the front-end figures more prominently in the control of the bike.

 

Now dial in some damping from the steering damper. Repeat the impulse test. If your bike showed signs of instability before the damping was added, crank up the damping until your impulse test generates an output wobble that quickly dies out. I’d say that 1 or 2 oscillations of the front end are tolerable. More than that and I’d feel a little uneasy. By adding damping in this way, you can tune the instability out of your steering systems while maintaining a quick response to steering inputs.

 

So when does this steering damper tuning matter the most? How about when you’re leaned over in a canyon around a 25 MPH turn with a passenger and camping gear and you have to grab a handful of brakes to avoid a family of yaks that are crossing the road. You will say a prayer of thanks to the steering damper gods then.

 

If you had a data acquisition setup and a few accelerometers, you could measure the steering gain and stability numerically from the impulse test responses. This is how the major manufacturers develop their bikes to handle well. The wobble mode impulse test is standard practice for evaluating steering response.

 

If more people performed this test on their bikes before hitting the back roads, we would hear fewer horror stories about accidents and near-accidents due to tank-slappers. Unfortunately, this is a litigitous society that we live in and there is some amount of skill required to perform this test. Manufacturers are not about to instruct owners to excite a potentially dangerous vibration mode of their motorcycles for fear of someone misinterpreting the information. It is, however, important for riders to be aware of the issue of adequate wobble stability.

 

Guzzi power.

Ed Milich

 

SOURCE: GuzziTech http://www.guzzitech.com/SteeringDamp-Ed_M.html

 

Ed Milich's Le Mans IV

[Dan M]

Now let me start with a forum saving disclaimer that I in no way want to start a war of words and personal attacks between the bra, er, damper burning liberals and the crank it up-tight conservatives.

 

I have to agree with RH here. I ride a long frame, albeit 13mm dropped triple clamp, LeMans. There is a long 100 mph left hand sweeper that I frequent. Midway through there is some rippled pavement, nothing extreme but the difference, measured in pucker value between hitting the undulations at speed with the damper set to 3 clicks as I usually have it and firmed up to 6 is enormous. My damper while hidden behind the fairing seems to have more value than cosmetics.

[GuzziMoto]

Nobody is saying that steering dampers don't affect the way a motorcycle handles. But not everybody likes the effect a damper has on Guzzi handling. Some would prefer to adjust the suspension so that the bike does not react poorly to bumps, so that the dampers actions are not required. It's very simple, there is more then one way to make a Guzzi handle well. And my way may be different then yours. I'm not saying anybody else should take off a damper that they feel is needed, but if someone does not feel the damper is needed, there is no reason for them not to try the bike without the damper and see if that is more to their liking.

The rake and trail numbers of a Guzzi make it inherently stable. It wants to go straight. Even if something knocks it off that course, it will want to restabilize. A damper will slow down the steering and make the bike feel even more stabil. It will also give you an extra measure of protection against poor handling over bumps and whatnot. But there are no free rides. It does that at the expense of quicker steering, which could also have it's own safety implications in the wrong situation. It comes down to personal choice. If you believe in that sort of thing. I do.

Theree is no right answer or wrong answer about a steering damper on a Guzzi. If there was, why do the new Guzzi's not come with them at all in spite of nearly the same geometry? And I don't believe a Griso or Breva is a dangerous bike to ride. Quite the contrary, They are very composed and ride much like a V11 without a steering damper.

 

Edit.. I would add that removing a steering damper from aV11 is no more dangerous to do then screwing with the fork height or shock length.

[Greg Field]

I rode a customer's bike for a week or so in effort to help diagnose a handling problem.

 

It was an intermittent problem that didn't seem to occur until at least 20 minutes in to a ride. Sometimes, it would start to feel like the rear tire was going flat, and then stop. I even pulled over a couple times because I was sure the tire was going flat. Sometimes it would begin a low-amplitude weave and then stop and then begin again, seemingly at random. The problem was an intermittently wonky steering damper. It was an Ohlins, too, on a Cafe SPort.

[Guzzirider]

I don't have my head buried too much in the science of these things- all I'd say is that the damper on my Rosso Corsa is permanently set on its lowest setting and I have never had any stability problems, tankslappers or wobbles. I've tracked it several times, raced it in a hill climb and thrashed it on some of the bumpiest roads around and its been the most stable bike I've ever owned.

[GuzziMoto]

I think it's safe to say that Guzzi's are pretty stabile by design. And if it is not, there is probably something wrong with the bike whether it is a bad steering damper or other chassis issues. My wifes V11, without a steering damper, is very stabile and yet is lighter and quicker steering then it was with a steering damper. Of course we have altered the front forks of her 01 sport to actually provide compression damping. Clearly I have no respect for how Guzzi wanted our bike to handle and ride.