ktk_ace
-
Posts
702 -
Joined
-
Last visited
-
Days Won
2
Posts posted by ktk_ace
-
-
The design of the bike makes such a difference here. Look at the footpeg position in the Rossi photo. It looks like the exhaust pipe or even the bellypan would touch down before his boot. That's nothing like the bikes most of us ride on the track. Rossi's body position is also not that close to my personal ideal, but what works best at 150 mph is not going to be the same as what works best at 65 mph. At a certain point sticking your knee out and getting your torso to the inside is just going to result in your being blown off the bike! Most of us don't really need to factor aerodynamics into our preferred cornering body position....
True that~
-
Ktk, I'm not entirely sure what your trying to demonstrate there , and how it applies to the thread, And I believe the relationship between Lean angle and Lateral acceleration is a TAN function so your plot shouldn't be linear
Opps, i was trying to reply to stroker's other post on the other thread ; sorry~
-
A point about using the knees to hang off.....notice how GP riders don't use their outside knee but rather the thigh part?See how Rossi's knee is not holding on to the tank but the inner thigh is? I have observed this among all GP riders.The knee sticks out, pointing outward at the sky or something.
maybe its because anything over a certain lean angle (i guess 50 or above )makes the rider get pushed down hard enough on the bike so much that a proper knee lock on to the tank isnt 100% necessary... hence rossi's "pose"
but if its 0-said lean angle (0-50 degrees of lean ?? ) , the g force might NOT be able to totally plant the rider on the seat , hence the need for a good lock on to the tank... esp with bumps mid corner as shown in above video clip.
I might be wrong thou...
-
It's interesting. The TC system that MV Agusta uses is also a sensor less system that depends on fast increases in engine RPM to determine TC intervention. I think the wheel sensors are a much better solution myself as it provides more realistic data to the computers deciding to retard the spark. It's not going to be fooled by someone playing with the clutch. I have to say if I owned a bike with one of those sensor less systems I would almost have to make it angry a few times with the clutch just to see it in action.
An interesting side effect of the wheel sensors is the data they collect. An S1000RR equipped with the datalogger is able to provide the rider a value called slip rate. It's essentially the difference in speed between the two wheels indicating some minor wheel spin. You can actually "see" the gradual loss of grip before the TC system engages. I plan on using the data from the datalogger to further explore the limits of traction in a controlled and sane manner. You could also use the data to dial in that perfect tire pressure on a track day. The TC system on the S1000RR is beyond amazing.
Ah slip ratio...
Have a look at this article:
http://www.sportrider.com/sportbikes/advanced-traction-control/
PS. goodies are in the pictures, press next to cycle thru the goodies.
also this article shows how different manufactureres use different stances to modulate torque in the TC systems:
http://www.motorcycle.com/how-to/traction-control-explained-91272.html
-
If you have already signed up for the school, you can probably get the student special discount on the q3s from the school and have them ship them to you, that may be a better deal than you can find locally.
X2 for the student discount!
-
Id say the remainder % that led to scrapping of the parts might be not using the 2 step for choosing a turn in entry (too early entry) + no quick flip
Or maybe hes just too heavy for the Z1000 in stock form.
Anyone with more than 170 pounds fully geared up on the Z1000 already has reduced clearance from the get go imho -
A picture tells a thousand words (English isnt my mother tongue BTW)
Anyway I draw better than i type so heres my own personal intepretation of the discussion above:
I included 2 variables as lean angle and G-force are related but not mutually exclusive (ie banked / chambered / incline/ downhill stituations)values with a "?" denotes that its a guesstimate and i have no research to back it up, just a hunch
Its in the rough so im open to suggestions ~ -
electronic aid took a few years to mature in the car industry...
Give bosch and the other manufactirers a few years to iron out and fine tune the stuff imho... -
Hehe....strange are the ways of the motorbike.
I still maintain a lighter and smaller rider can learn how to get around those disadvantages but a heavy rider cannot deal with his extra bulk.
I'm not sure it really matters either way. Heavier riders can use the weight as an advantage up to a point to help turn the bike with less effort. Lighter riders have more acceleration on the straights. In reality mixed in with the differences in abilities it all works out in the wash. This of course only applies to "mere mortal" riders rather than MotoGP which is it's own world all together.
I think the most important take away really is to identify where your build is an advantage and a disadvantage and exploit the advantages and minimize the disadvantages as much as you can. The classic "know thy self".
This is actually quite inspiring for me as I have been on a personal weight shedding mission in the quest of getting faster. It really does not matter as much as I thought it did. I'm not giving up on the personal weight shedding as being in the best possible physical shape is still an advantage. It's just nice to know that I'm not alone and the stick figure guys have their own set of disadvantages as well.
If you go abit "hardcore" and dev into suspension and bike geometry(esp trail and tree angle placement...) / frame / mass centraliziation...
A lighter rider WILL have much more advantage during the long run due to fuel economy alone ... (Suzuka 8 hrs anyone? or LEMANS 24hrs ...)
I dont even want to dev into brake pad life/shock fluid temps/tire wear ... these all cross over to commuting too.
more weight = more wear and tear.
but of course for racing ... unless the track is biased towards small bikes with next to no straights ,
the usual know how is how to maximize all 170-200hp's using modifications on a litre bike
; ie you already start off with too much power ; you have to make it more controllable/accessible and that requires personalization.
imho Bikes have rider weight "sweet spots" too... be on either end of the spectrum(too light or too heavy) and huge suspension mods might be necessary...
-
Good job!
Hopefully more podiums soon!! -
Michelin is producing the pilot road 4's which is a mix... wonder if it will be best of both worlds or just an over hyped product...
http://moto.michelin.com/tyres/michelin-pilot-road-4on the other hand, the new Dunlop D211 GP-A PRO's whith manufacturer approved flippability (rear only) really brings up a financial advantage to the racer!
http://www.sportrider.com/sportbike-news/dunlop-releases-bi-directional-sportmax-d211-gp-pro-tire?dom=sri&loc=contentwell&lnk=dunlop-releases-bidirectional-sportmax-d211-gpa-pro-tire -
2013 FJR1300A
TCs are not build the same ...
Yamaha...
Khreist, they are the 2nd Japanese big4 to venture into the TC realm in production bikes.(and that was late last year , slow as heck)
(Kawasaki being the 1st(ZX10R) and Honda being the 3rd on their VFR's)
Its gonna be very "prototype-y" aka unrefined until they wanna sort it out or some other manufacturer comes and bite their ass... HARD.
like the KTM 1290 superduke ( which has pretty unrefined ABS too for the 2013 production version...)
-
I do remember Mc Coy, and was also surprised to learn that spinning only heated the tire superficially.
But that was 160-170hp 2 stroke machinery.The heavier and 250 hp 4 strokes and the different tires of today may react differently.
Lorenzo's smooth corner speed oriented lines for instance load the tires a fair bit more than the pick up style of Marquez who tries to have the bike stood up as much as possible.However, Lorenzo has plenty of tire left at the closing laps, enough to charge and battle if need be.Marquez tries to work the tires from the start, get away a bit and then settle into a comfortable pace.
Stoner would sometimes run out of tire remember, and had to settle for second or third.If his sliding style caused less tire wear, maybe that should not have happened? I am curious on this matter.
That was before advance/mature TC systems (and ducati's tc systems are only beginning to show maturity on their street machines , which imho tells alot)
If you read up on TC systems, the 2011 production Kawasaki ZX10R actually permits (controlled) slippage with the use of wheel speed sensors alone (cost) and it does it very well imho.
Comparison
Tech jargon:
http://www.visordown.com/uploads/images/Large/21455.jpg
PS. The closest production bike next to a full blown WSBK bike will still be the BMW HP4 on virtue of its suite of sensors and active damping electronic suspension ... or untl some other company comes and play catch up
(which i bet wont be soon, not for the next 2-3 years , given the Japnese big 4 are pretty campy ... )
-
For generics , its pretty good.
There are some oddball exceptions thou , for example Honda's C-ABS / BMW's rear paralever/ front non-dive suspension linkage.
And by fast , i hope you mean aerodynamically stability , a naked street bike going 200KM/H will try to tear your face off ~ -
ABS Pro initially offered as retrofit to HP4 models
-
As Stroker said, replace the pads.
The pad material is porous material so the oil has already seeped deep inside.
Safety isnt worth saving 25-50 a set of pad material imho.
-
imho could be the tire compound as well...
but there IS less flex on radials , which can lean to warm ing problems and road holding capabilities on worn tarmacbias has more flex but the tradeoff is they are more prone to overheating during long stints
michelun pilot road 4's have this hybrid construction that mixes radial and bias pros into a tire, u might wanna givvit a look ^^
-
This is a cool topic. Something I'm taking away from it.
At the limit weight does matter. How many of us are able to ride at the limit though? Some riders are better at getting to the limits than others.
Regardless of my 214# weight my goal is to try to improve and get closer to that limit on the machine I am riding.
The Machine is also an important part of that limit equation. A bike designed to be ridden on the street has a number of compromises that make it comply with legal regulations and be able to survive longer than it's warranty period. MotoGP bikes don't have these limitations and allow the rider to get much closer to the limits of physics and even seem to defy them at times. In comparison to the bikes we ride on the streets the only similarity is the form factor. Virtually everything is a custom made prototype on the GP bike made from exotic materials.
It's nice to try and compare the raw science but there are way too many variables not taken into account. It's a really complex scenario involving man, machine and conditions. You would need a bank of supercomputers and still could not calculate the equation with any level of true precision in real time. The human element however throws all of that science straight out the window as as advanced as we are we are unable to accurately measure ourselves.
Oh well the Germans had started somewhere with the S1000RR HP4 ...
its still "gen 1" so give it a few years imho
-
I dunno im like a black box; if the tire pressure is off by 2 psi , i can feel it , im freaking sensitive.?
If the bike feels "sick" or funny, i'd just go to the shop for tire/basic inspection... Im usually right 99% of the time that somethings not right or off by 10% of normal parameters.
-
The bike I found easiest to ride, where I could still look around enjoying the scenery while throwing sparks (I only have ridden old bikes) was a Z400G, an old twin from 1979 where I had modded the fork internals for better damping and the correct ride height plus more progressive action through a higher oil level. The rear was fitted with Konis intended for the KZ1000, so quite a bit longer. The bike felt like an extension of my body. My weight is about 230 suited up. The bike 400 lb wet.
Another bike that was incredibly easy to ride was the Yamaha XJ600 Diversion with a wet weight of 260 lb. Very neutral, very nimble. Soggy suspension, but it wasn't problematic.
The bike I felt most secure on (I felt very, very secure on the 400, but it had a top speed of 75 mph and I'm sure 130 would have been, uhm, interesting what with the steep rake and little trail) was my CB1100F. It was very hard to change directions on, but even throwing sparks around 130 mph bumpy bends it never once deflected from its chosen line. It was 600 lb wet.
I found the Triumph Daytona 900 (540 lb) and the Kawasaki 750 Turbo (520 lb) to be real pigs to turn, both demanding extreme efforts to turn, even when ridden moderately. They are the two least favourable bikes I have ridden and both made my forearms hurt after just a couple of miles of riding hairpin roads. Surprisingly, the Triumph Sprint 900 (basically a Daytona with softer suspension and more comfy ergonomics) was a delight to ride and impressively tossable and the best bike I've ridden on radials. You couldn't be aggressive due to the ultra-soft suspension, but it was comfy and nimble.
In my personal findings, bike weight doesn't matter much, but how it is balanced and how the suspension is set up and how I fit the bike makes a lot of difference to me. I prefer a bike that steer quickly with low effort while always keeping its line without a fight, where every action from every input is predictable. The old Z400 offered that. I would always know right down the the inch where it would go. Never did I have to use conscious effort to steer it, nor did it ever wander off course or wobble or weave. It was utterly predictable in every way for my kind of riding, which is gnarly backroads. On a track, it would have been dwarfed, though
someone commented on the % of weight of rider VS bike and it seems that 50% (of rider weight vs bike) is the line between stable and really unstable...(for bone stock bikes)
based on the data you provided, it seems to add up ~ (Z400G is already optimized to your weight and style , sus damping/oil is a HUGE upgrade imho )
weight (bike + rider) doesnt show itself much on street and sport riding situations as the G forces acting on all parts doesnt really upset any component whatsoever (weakest link theory)
up the ante and weak points show up faster on a heavier rider... esp with antique bikes that werent designed with CAD / calibrated optimal stiffness technology .
its really like goldilocks (rider) and the porridge(chassis); too stiff and the other components take a beating ; too much flex and the bike wobbles around.
WSBK 2015 rules makes chassis "optimizations" all but outlawed with 0.003mm tolerance on the frame , else every team is just optimizing the "stock" frame to a rider's riding style by adding or shaving thickness on frame areas on 2014 and prior....
-
do you mean bias build tires?
radials (usually) offer lighter weight and heavier load bearing imho...
lighter unsprung weight = more compliant suspension
heavierr load bearing = more direct feel at same pressures.but if radials make your bike flinchy, then there MIGHT be a big problem with the rebound damping in the suspension system (much less of a problem with modern cartridge system shock/forks)
older bikes with damper rod systems tend to have this; bias tires with more weight helps keep part of the problem in check thou~
-
Well, yes, weight does matter but I'd suggest not in the way most posts consider. Being 6'4" and 290, I know this one first hand.
I've been riding for 7 years now, first on a Honda Fury, which is a factory chopper that actually handles well (dude, it's a Honda! ;-) that weighed 675 lbs. Traded that in for a BMW K1300s a year and a half ago, and took the level 1 class on the s1000rr at Thunderbolt in NJ just about a year ago. My K bike is 575 lbs & 64.5" wheelbase. the s1000rr is around 450 or so with a 56.4" wheelbase.
OK, now to the meat of it. And this is all based on my perceptions while riding these bikes, not scientifically. That said...
Rider weight affects COG of the bike and its geometry. All bikes are 'meant' to handle riders of certain height/weight whether they are intended to or not. So, my weight as a proportion of the bike is well over 50% (64.5%) for the s1000rr while being right around 50% (50.43%) on the K1300s. Riding the S, I feel very top heavy. Bike flicks in too aggressively, minor shifts of weight make the bike react and feel less stable. Leaning in on turns (haven't figured out how to knee drag yet so I'm very locked in) feels like the bike wants to low side.
Riding my K is exactly the opposite. Bike feels planted, leaning in I can go much harder on the lean and not feel out of kilter at all. I can get pretty solid lean angles with solid traction, and flick the bike at will. And I've taken this bike up to about 150 and felt solid and planted. The S on a track running at most 120? I was very uncomfortable going any faster and could not handle hard turning or lean. Especially in the 'octopus', the bane of my existence! So my next class I'll be riding my K.
Now, to verify this, I asked my son (6'4", 165) to ride my bike, while I rode his FZ6R, which is more a commuter bike with upright sitting position. His feedback is that my bike left sluggish and hard to turn in, couldn't get good lean angles no matter how hard he tried, and was just a brute on acceleration pretty much everywhere. His 420 pound bike felt very wierd indeed! No power, very skittish, wanted to low side, etc.
So, the net result of this very unscientific experiment? Seems bikes are meant to carry about 50% of their weight in meat when ridden aggressively. Anything above/below that changes the geometry and balance and makes the bike feel out of sorts. Longer wheelbases can help mitigate this a bit, but only a bit. Best to stick to the 50% marker as much as possible.
nice writeup!!
COG of bike + COG of rider MIGHT be factors too
Im 5"8 160 pounds with gear and during my big bike class....
The XJ6N (205KG) feels much more unstable as the gas tank is conventionally placed.
The NC700 (215KG) on the other hand, feels supremely planted with the gas tank below the seat .
Fun part is another student who is doing the same class ( lanky 6foot 150 pound guy) commented that he feels that the NC700s feels like a 160KG bike at low speeds.
He was surprised when i said that the NC700s is a full 215KG without fuel, 10KG more than the comparatively wobbly XJ6N~
thou a more scientific method for the bike COG experiment will be to find 2 bikes of the same weight and wheelbase (nc700S wheel base= 1525, XJ6N = 1440 ,MM) but totally different COG's.
For the biker COG... same bike as control, and same height+ weight but different COG /build rider (high COG = afro american american soccer player/bodybuilder , low COG = olympic ski team candidate?)
-
If you are top heavy, it helps more if you hang off top only imho.
Rider weight also affects lean angle clearance on stock untuned bikes; a heavier rider is gonna have less lean angle and vice versa.
-
Hi there
Kawasaki Crash Better?
in School Questions/General Discussion
Posted
Motorcycles are not built for crashing imho.
that said, steel chassis bikes are much more resilient to minor knocks imho.