| Author | Message | ||
     Catalan42 |
I put a damper on my Lightning as it would get headshake under some combinations of speed, modest lean, and rough pavement. The 2nd time it started growing in amplitude for 1-2 seconds and really scared me bad! I got the LSL damper for it (from American Sport Bike) and love the feeling. Unless you do a side-by-side test, you can't even tell it's there even when set to the max damping setting (8/8 clicks). I had postponed betting the Ohlins damper for the 1125R, but just found out that a friend crashed his CR getting on the freeway at normal speed due to a tank slapper. The seemingly random nature of the problems has convinced me to put a damper on the 1125R as a cheap preventative measure! | ||
| Jgarner99 |
Sorry to be a smart ass, but you asked for it when you changed to the dual-disc front wheel. Look up "moment of inertia," then meditate on how the masses of your fork, front wheel and brakes are acting as they pivot around the axis of your steering stem. You took one set of parameters (i.e. rake angle, trail measurement & frame rigidity), designed to work with a specific moment of inertia (i.e. stock ZTL front wheel & brake) and entered a completely different (and larger) set of forces into the equation. All modern sportbikes (just like fighter planes) are designed relatively close to being unstable -- it helps them to maneuver quicker. Your modifications changed the equation, and under certain circumstances, your bike is now going to be unstable. In other words, the self-damping, self-correcting stability built into your 1125 is, at times, going to be overpowered by the additional mass of your modified front end. The most likely time for that to happen is when your front wheel gets airborne, then comes down either cocked, with the bike slightly leaned, or with the rear wheel not in line with the direction of travel (a.k.a. "weave"). The best advice you've gotten so far, is that about loosening your grip and holding yourself up with your core muscles, but that isn't going to change the fact that your bike is now less stable than it was designed to be. I'd ride with a light touch on the bars, but also get a steering damper (set to a low value, just enough to add to the self-damping originally built into the system). Good luck, Mister Test Pilot. | ||
| Ezblast |
Concur! Love my GPR. EZ | ||
| Duphuckincati |
While we are on the subject, anyone have an opinion as to the "alleged" difference of instability between the R with fairing, and the CR,also with the different handlebars on the CR? I've only ridden my CR, and that's with the high bars. | ||
| Dannybuell |
I have had several tank slappers on my s1. They went away when I got the penske rear shock. I kept increasing the preload until it went away. | ||
| Fresnobuell |
The seemingly random nature of the problems has convinced me to put a damper on the 1125R as a cheap preventative measure! Oh, I bet they aren't random. | ||
| Dennis_c |
If the tank slaps you hit it back let it know who is the boss  | ||
| Jgarner99 |
> "Oh, I bet they aren't random." You're right on the money, Fresno. But it takes a pretty good grasp of physics -- and an even deeper understanding of the dynamics specific to 2-wheel vehicles -- to connect the dots. | ||
| Cowboytutt |
Wow, with friends like us, he sure doesn't need any enemies. Sad to see. I'm embarrassed to be a Bueller. -Tutt | ||
| Bwbhighspl |
Wow, with friends like us, he sure doesn't need any enemies. Sad to see. I'm embarrassed to be a Bueller. -Tutt I suppose we could go through sensitivity training to soften the advice people don't want to hear, but it would end up like the bible: Lost In Translation | ||
| Cowboytutt |
Post edited. Just wanted to say that: Avalaugh has been a good "forumite" for a long time, never seen him have a bad word to say about anyone or anything. He deserves better. He can ride with me and the SCAB group in SoCal anytime he wants. He is a good guy as far as I'm concerned. -Tutt (Message edited by cowboytutt on May 05, 2011) (Message edited by cowboytutt on May 05, 2011) | ||
| Avalaugh |
I take from peoples comments what I want, what they don't know is that I have very light discs and mounting bolts, also that my yokes and clip-ons are also lightweight, my MC is also lighter than stock. I dont think there is much weight increase at all. However the point being expressed is correct, although not necessarily apply to me. All forums are the same tutt, but also offer vast amounts of information which is why we all use them. Thanks for the support, some people are just very opinionated | ||
| Therealassmikeg |
Well.. I guess you could be scientific here. Install a damper, go back to "Tank Slapper Rd" and try it again... | ||
| Avalaugh |
Lol, I don't think do  I will adjust my riding style a bit, and get a damper when funds allow, I will also get dome tuition later in the year. | ||
| Sl33py |
Agree with Tutt. I am impressed he was so forthcoming and humble about what must've been one hell of a scare. If it were me there would be skid marks on more than just the roadway...  He asked for help - i don't think it deserves the heavy handed responses. I think everyone has a good point, and it looks like some suspension settings should be dialed in. A dampener would probably help (i'd like one just in case - like others have said cheap insurance). I've had head shake on some fast(ish) exits, but understandably 100% my riding and easily controlled. my .02 at least. great pics and must've been one hell of a ride! nice job keeping it in your lane! | ||
| Catalan42 |
---"Oh, I bet they aren't random." I'm not sure what you mean by that! Of course, everything is ultimately based on physics, but it is damn near impossible to predict how a complex non-linear dynamic system like motorcycle steering will behave under all circumstances (as an MSEE, non-linear dynamics was the hardest class I've ever taken....by far). Besides basic geometry, other important variables include rider weight & distribution, control inputs, speed, acceleration, braking, lean angle, tire construction, wear, pressure, frame flexing & twisting under various loads, and the rate of change & acceleration of all the above. The above are just the items you can control. We haven't even discussed road conditions yet (roughness, crown, age, clean/dirty/wet), manufacturing tolerances, wear, defects/breakdowns or the actions of other drivers. Those variables are all beyond control or prediction. It is for reasons like these that NASA still has flight tests - one cannot analyze or predict everything. If you must be picky, I could have used the word "unpredictable" in the original post instead of the word "random," although you probably won't care about the distinction between these two if you are in the hospital. The upshot of all this is that, because of the unpredictability of tankslappers in high-performance bikes, a damper is cheap insurance against an unlikely but potentially catastrophic event. Even the Ohlins unit is cheap compared to bike repairs or a hospital stay (or even a coupla pair of tires!). | ||
| Thefleshrocket |
Maybe I missed something, but it doesn't seem like anyone has said anything especially mean or abrasive. A few people could have probably been a bit gentler in how they offered advice, but nothing I've read would have hurt my feelings if I was the original poster. PS, does anyone have a used steering damper for sale? LOL | ||
| Fresnobuell |
I'm not sure what you mean by that! I mean it's something the rider is doing--not the bike. Whether it be thru riding technique or bad suspension setup, it's the rider's fault not the bike. You can buy a damper, but it's been mentioned before, you are dealing with symptoms not the root problem. I have ridden nearly 25,000 miles on my Rs and the only instability in the front end (ie side to side motion) is on acceleration when the front tire gets light but doesn't lift. And I am still not blaming the bike as I am sure I clamp on too tight to the handlebars (throttle hand in particular) in those situations. I am working on my technique. | ||
| Catalan42 |
Thefleshrocket - I don't feel that anything posted above was mean, I just think it is dangerous to make vague suggestions that suspension tuning, steering technique, or an extra rotor will make the difference between safety & disaster. The fact that many high-performance bikes come stock with a damper (and that racers use them) says loads about their value. | ||
| Jdugger |
I don't think anyone has touched on the downside of a damper, though. And, that is, when the front should just push a little and twitch back to normal, the damper keeps the steering in the incorrect setting for a longer period of time, enhancing the chance of a low-side from not picking the front back up. If you do use a damper, setting it towards its minimum setting is the best practice, IMHO. | ||
| Fresnobuell |
Good point JD. Bikes want to stay upright and dampers somewhat prohibit the free movement (and hamper the natural correction ability) of the wheels. | ||
| Buellrain |
Agree with “Tutt’s” original post! As much as I love my CR and Eric’s innovative creations, the whole background of Buell’s story and almost a “David and Goliath” aura, I don’t kid myself into believing the bike is more than what it is.. Mass centralization, in some case’s oil in the swing arm and perimeter brakes are cool, not too sure about the belt drive? But for lack of maintenance it suits me. While watching the Portuguese Moto GP last weekend, correct me if I’m wrong but I did’nt see any bikes in any of the three classes with single disc perimeter brakes… Why? Because in reality they are simply not good enough ! The srories of the XB’s or 1125’s catching up on the mountain pass etc are a nice idea, but in reality are BULL!!! If you put two equally talented riders on a XB or a 1125 against a Jap 600 or 750 my money’s on the Jap bike, let alone the liter plus bikes. “Avalaugh” obviously has a passion for his “R” and did a twin disc upgrade to get the most out of it… these bikes are known for “headshake” and I’m sure that in original form with a fist full of throttle over a rise the result would have been the same, he no doubt took a lot of time analyzing the front end conversation and went with lightweight components. It may have been better for him to trade the bike for something else, but the fact is that these bikes in the UK aren’t easy to move on but they do have the unusual factor about them. Let’s face it, how many of us push these bike’s to the limit? It’s on the limit that these issues arise and that’s where “Avalaugh” found himself. Hopefully my bike will never be for sale and I fully support Erik Buell Racing in their endeavor’s, I would love to see them kick the butt of the BIG Boy’s, but if I had the money and wanted to be “king of the hill” I’d have a BMW S1000RR for those days and keep the Buell for fun and uniqueness. A few weeks ago I went riding with 3 S1000RR’s, 2 1198’s and a bunch of Blades, on the straights they were pulling 300+kph in another league! Although at the café afterwards the Buell was what the people ogled over……………… Buell, it’s unique, it’s individual, it’s fun, it’s cool, it’s attractive, it’s unusual, it’s a good story to tell, it’s problematic but it an’it, not yet “King of the Hill”…………………………. | ||
| Fresnobuell |
The srories of the XB’s or 1125’s catching up on the mountain pass etc are a nice idea, but in reality are BULL!!! If you put two equally talented riders on a XB or a 1125 against a Jap 600 or 750 my money’s on the Jap bike, let alone the liter plus bikes. Did Curve-Carver get banned and re-sign on as Buellrain? What a loaded statement. The XB can hang depending on the road if it doesn't have straights. The 1125r is easier to ride fast so I would state the opposite to be true--my money is on the R versus the 600, 750. as far as literbikes, the only time they have a distinct advantage is outright horsepower--which means long straights. I don't see them having much of an advantage on a "mountain pass" assuming our definitions of a mountain pass are simliar. | ||
| Fresnobuell |
Also, I can state for a fact in technical twisties I was faster on my XB9SX than my R. I suspect the shorter wheelbase was the factor here and the lack of HP might have been an advantage as I could get on the throttle early and not fear breaking the rear loose. | ||
| Avalaugh |
Buellrain, I agree to all you said, that is the exact reason I bought the 1125 in the first place, only ever seen 3 other 1125's and 2 are forum members. They are rare, that's what I like. | ||
| Fresnobuell |
on the straights they were pulling 300+kph I don't believe that--maybe indicated. 300Kph is 186 mph and not only are most bikes electronically limited to 300KPH, it would take miles of a straight with ideal conditions (ie no traffic, no sidestreets, no cops) to pull this off. At least here in California, I personally find those places very few and far between, but maybe I am picky about where i am willing to test the limits of my bike on public roads.} | ||
| Davegess |
Oh Oh we are starting another perimeter brake thread. These are worse the political ones. Could we just paste in links to the last 107 of them and save the bandwidth? | ||
| Buellrain |
My previous post was NOT intended to offend anyone, it’s in my opinion what I believe to be Fact! However I did think twice before posting but I figured as a group we are big enough and open minded enough to view other’s opinions without taking it personally. No I am not Curve-carver reborn as Buellrain…. Fresno, as for hitting 300kph, you would be surprised how little road you need to do it on, with a Superbike.. you may be right about “indication error” but either way it’s still bloody quick and made my CR look like it was standing still past 100mph. With the rider aids such as launch control, wheelie control, anti skid, abs etc these newer generation bikes are a lot easier to push without exceeded your own limitations, I agree it takes away a certain element of skill but it’s the way of the future… We all love the manual gearbox and enjoy the skill of “heel and toe” to downshift a car, left foot braking used to be an artform, but these days most race cars are paddle shift or some form of sequential, the clutch is out of the equation, the right foot is to go and the left to stop, just like a kart. No I don’t live in Cali, but did live there around 10 years ago and had the pleasure of riding up Palomar and Julian, it was a lot of fun and met a lot of great people. Anyway boy’s off to bed now as have an early flight to Iraq in the morning, apologies’ for any offence taken. Good night | ||
| Cowboytutt |
Yup, definately not Curve-Carver. Way too congenial...  -Tutt | ||
| Blake |
>>> While watching the Portuguese Moto GP last weekend, correct me if I’m wrong but I did’nt see any bikes in any of the three classes with single disc perimeter brakes… Why? Because in reality they are simply not good enough ! You don't know reality. In reality, they've yet to be further developed and tried in that series. In reality the single disk perimeter brake is indeed well proven to work for a superbike, one of which was "the fastest bike (Geoff May) has ever ridden", another of which won an open class superbike race in Europe and the twins thunderbike championship, so in carbon form should be able to also prove itself in MotoGP where bikes and riders weigh even less. Facts and reality are something that we can talk about in tangible terms. You can't just make it up as you go. |
