- 2 days ago
How many ways have motorcycle designers gotten it wrong? So many! One of these was chasing an ultra-low center of gravity on motorcycles, only to find it made handling worse! How have we settled on 20-22 inches off the ground for center of gravity? Because it works, and transfers weight on the front wheel during braking and to the rear wheel when accelerating. The right C of G also assists us when tipping into a corner. Technical Editor Kevin Cameron and Editor-in-Chief Mark Hoyer discuss motorcycle weight transfer and motorcycling handling. Our favorite moments of weight transfer? Wheelies and stoppies, of course!
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SportsTranscript
00:00:00welcome to the second world podcast we appreciate you being here uh share with your friends
00:00:06thanks uh thanks for joining us this week's topic is weight transfer and motorcycle handling
00:00:13weight transfer in the most extreme forms wheelies and stoppies very exciting yes i've had a stoppy
00:00:21at mugello in an area where you would not want to stoppy and i managed because it was one of
00:00:28the
00:00:28early awesome radial brakes i was able to be up and being uh breathless so you go through a chicane
00:00:36at the top of of mugello when you go up the hill there's a little chicane and then you accelerate
00:00:40hard to the downhill and uh boy that was exciting but the brakes it was one of the early uh
00:00:46radial
00:00:46mount brakes i think top and bottom um aprilia mile 1000 uh factory the v twin and it was a
00:00:54great
00:00:55it was a great case for ultra precise modulation because i was able to i was able to release
00:01:01precisely and enough to get the bike to stop from continuing because once you get over that center
00:01:06past the balance point you're done on the other side there's no especially a stoppy because you
00:01:12can't you know wheelies you can maybe stab the brake or you need front drive then yeah yeah so gas
00:01:19the
00:01:19front um very important we've seen a lot of experiments with this and we've had so many
00:01:25different ideas of where the rider sits gosh it's a good topic and uh that's why we're using it yes
00:01:36so yeah here goes here goes hit the uh i've just thrown the pitch kevin swing yes
00:01:41swing and a miss anyway uh we've all seen automobiles squat down at the rear while they're
00:01:49accelerating we've seen automobiles dive at the front when they're braking and motorcycles do these
00:01:55things much more uh than cars do because their center of mass is higher at least it's higher than
00:02:06uh the center of mass of racing cars uh the center of mass of racing cars and their wheelbase is
00:02:10roughly one half that of a car so here's what causes weight transfer we know that braking or
00:02:22accelerating force takes place at the pavement surface so its height is zero however the inertia force
00:02:31if you're braking uh the the inertia force of the vehicle's kinetic energy is acting
00:02:43at the center of mass height the cg height and on a motorcycle this is um
00:02:5220 22 inches or so that is the lever the force acting on the lever is
00:03:01is the braking force and when that torque cg height in feet times the force gives you foot pounds just
00:03:10like with a wrench when that equals the let's say we're braking here um the wheelbase times the load on
00:03:23the rear wheel is the torque level we have to reach in order to
00:03:28just get the rear wheel up a little bit and uh the same thing for uh acceleration
00:03:37so we're we're just looking at a little arithmetic here the basics are the force acts at ground level
00:03:45the vehicle acts like its mass is focused at 20 or 22 inches above the pavement so you apply the
00:03:54brakes or
00:03:54you hit the gas and you're going to transfer weight from one wheel to the other and
00:04:01some practical examples are useful um years and years ago the late hurley wilbert america's great
00:04:12rider tuner um he he actually got one of those 750 air cooled kawasaki two strokes to finish second
00:04:22at daytona that was that was the highest finish um at daytona of any of those bikes so 750s and
00:04:31hurley did
00:04:32that because he was a practical man and he was a thinker as i will now uh reveal
00:04:39he called me to tell me that he'd ridden two bikes back to back he had built his own bike
00:04:44chassis and
00:04:45setup in the ye old english style weight as low as possible weight low center of gravity is the key
00:04:55to handling people people worshiped in that church for years and i must say i did more than had a
00:05:03look in
00:05:04the front door too so mea culpa but he said the other bike which was prepared by um randall m
00:05:14hall who
00:05:15was a controversial figure at kawasaki had a noticeably taller uh higher engine position
00:05:24and he said i rode those bikes back to back same day and i have to tell you i was
00:05:33quicker
00:05:34on the tall bike
00:05:38and he said at first i i just wanted to reject that idea because we don't want to build a
00:05:45slow bike
00:05:46intentionally it can't be true right let's make this thing slow oh success it's a it's a anyway
00:05:55he said i've i've thought about this a lot and i want to tell you my conclusions he said if
00:06:01you're
00:06:03accelerating on a low bike lower center of mass it has less leverage uh to lift the front or to
00:06:11unweight it and he said um and less effect of transferring that weight to the rear tire
00:06:19so he said on my low bike the symptom was it it wasn't accelerating as strongly off corners it was
00:06:28tending to maybe slip and slide a little but on the tall bike hooked up and accelerated and what was
00:06:38going on here he said was that the taller bike transferred more weight onto the drive wheel
00:06:45and provided that there was enough on the front wheel to steer it made that bike accelerate
00:06:51so uh quicker lap times on the taller bike
00:06:59then we have uh the example of yvonne duamel had a closed kawasaki test
00:07:07at the old ontario speedway in ontario california and this was 1972 just a year after the peak
00:07:18of the mania for long swing arms your bike handles bad put on the long swing arm it'll settle it
00:07:23right
00:07:23down so eval goes out on this bike which has a longer than than usual swing arm and he's just
00:07:33not
00:07:34getting down to lap times that he's done previously what can be the trouble round and round he goes he
00:07:41said when i try to gas it uh it spins instead of accelerates doesn't go forward it goes sideways
00:07:51and eval always spoke in a kind of uh charming nasal whine and he was a man of considerable humor
00:08:00he
00:08:01enjoyed life's little contradictions no miguel was the same way he was very funny covering miguel when
00:08:08i was covered doing some some race coverage back in the day and the other guys were doing more of
00:08:13that but quotes from miguel in a road race story from road atlanta or whatever we're always great
00:08:18like oh he's gonna be i thought the guy in front of me was going to put the kickstand down
00:08:22because
00:08:23they were trying to avoid being drafted you know god he was he's good very funny guy and obviously
00:08:29massively talented just like so there they have a little conference about this mama mama mama what's
00:08:36different from the last time we tested here swing arm hmm okay what do we got here is there anything
00:08:44in
00:08:44the truck somebody nimbly hops up in there and in a manner that white haired guys like myself can no
00:08:51longer do any there's crashing and banging uh as you expect when people are looking for something in
00:08:59a hurry and he comes out holding up a stock h1r swing arm in one hand they had piles of
00:09:05those things
00:09:06they had piles of the special 35 millimeter vm carburetors made for the 500 they boxes of them
00:09:13i think they had to buy a minimum quantity there's probably still some anyway um they put the stock
00:09:21swing arm on uh take care of the details like ride height blah blah blah evon goes out and immediately
00:09:30his times come right down and he comes in beaming he says how's that and they show him the board
00:09:38all as well so what was happening by shortening the wheelbase see dragsters have long wheelbases
00:09:48to avoid wheelies uh what they're trying to do here to get evon's bike to hook up and accelerate
00:09:55is to transfer more weight onto the rear tire if you tuck push the tire forward
00:10:03it's easier for it to do that i'm sure dart trackers do it all the time because the surface they
00:10:09race on
00:10:09is constantly changing oh here comes the water truck oh here comes the sunlight oh it's cooling off in the
00:10:15in evening so uh that was a success that change worked so um
00:10:28um that shows the value of putting weight on the rear tire so that it doesn't spin but instead hooks
00:10:39up
00:10:39and drives now see i want to why i want to ask yvonne how the front was with the long
00:10:46swing arm was that
00:10:46better or was that worse well he he wasn't getting enough power down to make to make the front have
00:10:54a
00:10:54problem so uh another example here is and i've used these examples before
00:11:06but uh valentino rossi in 2008 switched from michelins which he had used for a long time
00:11:16to bridgestones and the reason that everyone was in a mad scramble to do so
00:11:22um was that michelin had made uh an incorrect response to a rules change the rules change said
00:11:31no you can't wait until uh saturday to to make the tires for sunday the tires all have to be
00:11:39here
00:11:40thursday beforehand or whatever day explain that because that's a that was a time to be alive is
00:11:46oh man overnight tires based on the weather and what had happened up to that point and then back
00:11:52in the factory okay mixing up the tire and then putting it in the machine and then knocking out the
00:11:58race tires and flying them to the track amazing that's what they did or they they they drove them to
00:12:05the
00:12:05track if it was sort of within the compact part of western europe swaying over the over the highways
00:12:12and of course what they were trying to do was to have the right tire compound for the temperature
00:12:18expected on on sunday and bridgestone well michelin always compounded in a very temperature sensitive
00:12:30way that they had family of of rubber compounds that the peak grip if you were at the temperature
00:12:36that they were made for was fantastic but if the grip was five degrees centigrade different
00:12:43there might not be very much of it bridgestone being half a world away
00:12:50said to themselves we can't we can't fly our tires out there uh saturday night it's too far
00:13:00so we're going to have to make a wider temperature range family of tread compounds which they did so
00:13:07here's valentino and he's on this uh on bridgestones he's rushing up from turn six to the top of the
00:13:15hill
00:13:15at laguna seca and breaking and in order to get down to corner speed he finds he has to break
00:13:2240 feet
00:13:23sooner than he had done on the previous tire now you have to realize all these race teams carry digital
00:13:31histories of everything that's ever been done it's all on the computer and there's more than one there's
00:13:37more than one copy so um what's going on here
00:13:45so um jerry burgess uh valentino's crew chief at that time tries all the things you try nothing
00:13:56worked nothing and as burgess likes to say uh paralleling sherlock holmes uh when when um
00:14:06the obvious solutions turn out not to be the the answer what is left must be the answer so they
00:14:17raised the bike
00:14:20and the 40 feet disappeared and based upon what we've said here so far you can see that a taller
00:14:30bike has a higher center of gravity more leverage to transfer weight quickly onto the front tire
00:14:37now tires are at a disadvantage at the beginning of braking because they have cooled all the way down
00:14:44the straightaway to that point tire grip is very sensitive to temperature so this is why the tire
00:14:53guys are always asking the rider about initial grip versus mid braking grip because if initial grip is too
00:15:03low then they've got a problem and in this case raising the bike a few millimeters added enough weight
00:15:11transfer to make the front tire to load it hard enough to grip so that they he could then get
00:15:21the bike down to corner speed in the normal distance braking distance so i think that's a valuable lesson
00:15:29right there because here uh you might think well we dragsters are low to keep the front end down
00:15:38maybe we should lower the bike to improve braking which is just the opposite of acceleration but no doesn't work
00:15:46that way so that's uh getting some weight uh on the front so a few years later i'm watching uh
00:15:59super
00:15:59bike practice at loud in new hampshire and there's a rider having trouble getting off 13 which is
00:16:06the turn out of the infield on to the little dinky straightaway they have there
00:16:11and i see him trying to accelerate and bike is going wide and with a kind of resentful
00:16:22shake of his shoulders it was like oh all right then he leans forward and pulls himself
00:16:29forward to move weight over the front tire
00:16:34now uh there's a little 1950s book by piero taruffi who was so important in making the gelera four
00:16:46happen because he was the man who knew everything he wrote a book a little book called the technique of
00:16:51motor racing and in one of the pages there's a curve of tire load versus tire grip and it goes
00:17:00up linearly
00:17:02and then it softens and it starts down what's happening there and with the softening is
00:17:09that increasing load is cause is increasing the area of true contact between the rubber and the fine
00:17:18details of the pavement texture notice what i'm not saying
00:17:24uh i may have to just say it asperities asperities yes so uh
00:17:40it starts to soften because although because the tire has filled in has has deformed to the maximum
00:17:48that it can and now what's happening is is the rubber strong enough to transmit the force
00:17:55or have we just made a cheese grater
00:17:59and that's how a blackie is left in a in a in a corner
00:18:04if the tires turning into a cheese grater situation so yeah uh that um
00:18:13business meant that this rider um had not yet reached the peak he just didn't have enough
00:18:21load on the front tire to get the grip he needed to keep turning while he was accelerating so he
00:18:27oh all right i'll lean forward oh my arm doesn't feel good now reminds me of uh nicky hayden going
00:18:34into turn 11 at lacuna seca i don't remember what year it was but he was going in deep and
00:18:40trying to
00:18:40i think he was trying to make a pass or block a pass but he went in and you could
00:18:44see it in slow
00:18:45motion they went back it was beautiful he's breaking super hard right so the you watch the front
00:18:49end so when you're applying the brakes in a racing situation and even on the street
00:18:53you want you want swift and ultra precise from no braking to so you're squeezing the suspension
00:19:00whatever that uh sag is going to be that braking force and then you squeeze the tire and that's all
00:19:06you have and so you could see him sick and then the tire squeezes down and there he is and
00:19:13he's a
00:19:13little bit maybe he's somewhere else in the track but there's a small bump and there was nothing left
00:19:18to give he was going in as deep and hard as he could and that little bump there was no
00:19:25more the
00:19:25tire couldn't take it the spring yeah and it just you watch the the light appear under his tire and
00:19:32down
00:19:32he went so what if what a feeling yes we felt this yes what a feeling um near the end
00:19:45of the 1980s
00:19:46the people were getting a lot more experience with four stroke um race bikes and
00:19:57a problem was appearing squat and push
00:20:03bikes whose riders were trying to accelerate early in a corner
00:20:10um so as to make the straightaway as long as possible
00:20:15are we're noticing that as they tried to accelerate if their chassis setup was such that the bike squatted
00:20:23down at the back it made the front end push and i saw a classic example of this again at
00:20:31turn 11
00:20:31uh i've spent a lot of time there um
00:20:37at laguna and here comes um
00:20:42alex barrows on the kajiva
00:20:47what a comparison with
00:20:49wayne rainey wayne rainey is approaching this turn
00:20:52and he's making all sorts of preparations you can see him moving on the bike
00:20:56he lifts his inside knee just in time to clear the uh the border
00:21:04bricks or whatever it is raised curb
00:21:07and he is pulling himself forward on the bike and moving his elbows and knees away from the
00:21:14motorcycle because he's expecting the motorcycle to be
00:21:17doing all sorts of violent stuff and he doesn't want the steering interfered with
00:21:22by those gyrations so he's he's basically hanging from the high bar with his arms bent
00:21:31he's holding himself forward like that but poor barrows he's 19 years old or whatever he was at the time
00:21:38not very experienced his butt is back against the seat stop
00:21:43and you can see as he's trying to dig the front end and it won't and he comes in from
00:21:50that practice
00:21:51and he's he's talking to his team
00:21:55uh and he's making the air motorcycle with his hands
00:21:58and he's showing he's he's digging it in
00:22:03and it closes as they say
00:22:05you only see that there's like there's chatter
00:22:07and then there's crossing the front like losing the front
00:22:11oh boy we've seen various hit videos where we string all those gestures together what are they
00:22:17saying it's good what i love i love the paddock gestures it's good stuff
00:22:23and well it's actually a language that um is useful because there's a lot of noise trackside
00:22:33freddie at one time was um
00:22:37not too good at remembering different things that
00:22:42they wanted him to do on the racetrack and you come in and they
00:22:45they ask him well did you did you look at the tack in turn eight
00:22:50oh i'm sorry i forgot yeah because he had other things to do
00:22:56yeah he didn't keep a scratch pad with a pencil on a string tape to the tank
00:23:02he had work out there well anyway that's what i like about the test pilots and the you know
00:23:07your chuck yeagers and all those guys they they get into some horrific flat spin that they
00:23:13they're never going to recover from but he's he's writing on the clipboard that's strapped to his
00:23:18leg you know cross control not functional whatever and then okay eject
00:23:27farewell yeah our hands are too busy there's we're just if you're in a flat spin on a motorcycle
00:23:32there's no writing well um this this squat and push thing was a real bother because it didn't seem to
00:23:42afflict everyone and uh
00:23:48it was finally
00:23:51it was finally analyzed properly
00:23:56by among others olien's and they published a little four page paper on it which became a treasured
00:24:03item hey anybody seen a copy of that because you could see that there were there were teams going
00:24:09to the olien's truck asking for really stiff rear springs and of course what they were trying to
00:24:16do is prevent the motorcycle forcibly prevent it from squatting and of course the stiffer your
00:24:23suspension is the greater the height that a bump will toss you the more air time you get and the
00:24:29farther you move sideways possibly enough to lose grip all together so we don't want extremely stiff
00:24:37well great if enough great alan girdler quote uh i was talking to him about my liberta 3cl which
00:24:44was a 1970s italian motorcycle with a thousand cc triple and i said you know man the suspension on
00:24:50this thing is really stiff it's kind of brutal and he said well in the 70s the best way to
00:24:55make
00:24:55suspension to uh work was to not let it so yes you ended up with no movement and that was
00:25:02probably
00:25:02the best the best solution at the time
00:25:07well uh this needed a needed a solution and the solution was found it turns out that
00:25:18the angle between the top run of the drive chain and the a plane drawn through the
00:25:29swing arm pivot and rear axle the central plane of the swing arm that angle
00:25:37working powered by the tension in the chain produces a lift force tending to push the swing arm down
00:25:47hmm maybe we could uh use that to cancel the squat and if we cancel the squat that ought to
00:25:56cancel the push
00:25:57and then we'll win the race and be heroes well like it says in the song fighting the girls from
00:26:06off in my
00:26:06back so that's the 50s song so you have to apologize for their lack of sensitivity
00:26:13a moment of silence for them uh but
00:26:19the question was how do we change that angle well every time you change the sprockets you're changing
00:26:25the angle between the chain and the swing arm which is why some places the rider would have this
00:26:32problem and other places not so it's like it was like zeus's thunderbolts striking at random amongst us
00:26:40mortals it couldn't be understood but this new understanding showed that it could be conquered
00:26:47because if you change the height of the swing arm pivot you would change the angle of the central plane
00:26:55so by raising the swing arm pivot you would increase the anti-squat force produced by the chain angle
00:27:06also if you put on a bigger rear sprocket etc so this it became possible this way to
00:27:18fight plot and push right out of the picture and that's why early 90s bikes uh super sport and
00:27:30superbike homologation jobs were given adjustable swing arm pivot height usually in the form of of a
00:27:40little metal box on either side and you could put plates into that box that had the pivot hole at
00:27:48different heights which would be stamped into the plate um so you know that's all you wanted as a
00:27:58kid at least when i was a kid it's like oh the whole the halligation special would come out and
00:28:02you're
00:28:02like i want that i don't know how to use it but it's got to be good
00:28:06yeah well mysteries are very cool we love mysteries watch them every evening in some cases anyway um
00:28:20this sort of got the got the thing under control but i went to uh
00:28:28the oleans tech and i said um doesn't everybody have a copy of your uh little dissertation
00:28:36oh no he said we had a subscription list and i put you on there because i thought you'd like
00:28:42it
00:28:42i did like it i gotta find a copy of that yeah so um that made it possible to for
00:28:52some people at least
00:28:53uh to give up using super stiff springs at the back in an attempt to conquer uh squat and push
00:29:03well now
00:29:06somebody turned this idea around and said
00:29:10well i wonder if this would work at the front if we made a device that kept a constant ride
00:29:18height at the front during braking maybe everything would be you know better so there was a period of
00:29:26error
00:29:28and during this period all sorts of mechanical and hydraulic anti-dive systems were made really quite
00:29:39ingenious you can see them in photographs from that time uh
00:29:44uh rods levers heim joints external hydraulic lines we're going to level this thing off and we're
00:29:52going to have wonderful braking nope didn't work i was all over production bikes
00:30:02yeah yeah yeah yamaha did some testing and they found that a bike that dived
00:30:11particularly if the rider first applied the rear brake somewhat when you apply the rear brake the torque
00:30:18is applied not to the chassis but to the swing arm so the rotation of the wheel tends to
00:30:26produce a squat effect to lower the rear of the bike and uh when
00:30:34um skip axlin went to talk to kenny who'd been hurt in practice uh 1980 i think skip said um
00:30:45people are
00:30:46out braking me at daytona and kenny said do you ever think of applying the rear brake the instant before
00:30:54you apply the front
00:30:55the front was like uh wonderful words from olympus but what do they mean it's like when
00:31:06when the when the persian army was approaching in in greece the the uh olympians the words were
00:31:21the greeks the persians shall subdue
00:31:27that could mean either thing
00:31:31amphiboly they call it anyway um so are we adding that to the the vocabulary list
00:31:39in many cases though uh you can tell people something and because they've heard so many rumors
00:31:49in their lives paddock rumors you know they just come
00:31:53oh they did this and here's what happened it's great gotta try it it's easy to dismiss this stuff
00:32:00yeah if i had some bread i'd make a sandwich if i had some meat yes so
00:32:08uh yamaha's experiment showed that letting the bike dive particularly if the rear end was uh squatted by
00:32:17applying the rear brake to lowered the center of mass giving the deceleration force less leverage with
00:32:26which to lift the rear wheel well bmw did a similar uh experiment with their telelever when they were
00:32:34you know looking at how to build telelever telelever is the lower a arm on the fork so
00:32:42you know you have an upper crown and you know the it puts the braking force into the chassis it's
00:32:47a
00:32:47big a arm and has a ball joint until ever you know it's it's pretty good suspension does a good
00:32:53job but
00:32:54you can tune anti-dive into it uh just like you can with a hossack front end yeah and they
00:33:02experimented
00:33:03with a little like dive let's get rid of dive and it was a big indication for riders how hard
00:33:09am i
00:33:09braking how far is the front going down and also putting putting the weight on the front as we're
00:33:15talking about weight transfer um perhaps there's something going on with geometry kevin doing the math
00:33:21but uh you want the front i mean you know i want the front and everybody else wanted the front
00:33:26so
00:33:26they've tuned in dive to give as a way of control as a as a uh measurement
00:33:34allowed them to say oh i'm braking pretty pretty hard here because and luca catalora was one of the
00:33:41people that complained particularly about that people were saying oh i want this really stiff
00:33:46suspension because it it makes the bike respond quicker to your control inputs luca catalora didn't
00:33:53want that he he wanted the front end to dive a bunch so he couldn't put you know springs with
00:34:00inch thick wire in there uh stiff ones because he wanted the front dive to measure for him his braking
00:34:07level and this is one of the things that's hardest for engineers to understand because when they talk to
00:34:16riders they don't hear uh it doesn't sound like the physics professor it sounds like a lay
00:34:22person meat bags and they dismiss it meat bag full of feelings we're feeling things we have emotions
00:34:30and uh and as you've always said the safety net you know you've done things over and over and you
00:34:36found a way to do it that is repeatable and you don't end up on the pavement and you're going
00:34:40fast
00:34:41enough and then when you try to go faster you have to experiment with new things but uh yeah i'm
00:34:47a
00:34:47third place writer so i just relax back here it's emotional well you know freddie spencer's got a
00:34:52book out i got to get a copy of it but it's called feel and it's about him oh very
00:34:57good yeah it's about
00:34:58him re you know riding and um you know something to do with intuition and you know he's really into
00:35:06it it's cool i want to check that out
00:35:10well uh so much for anti-dive now we can move on to some other examples leading to new technologies
00:35:22well i i think i would like to bring up unless you have it somewhere in your brain pan on
00:35:28the list but
00:35:281984 nsr 500 that oh yeah that was a wonderful experiment by honda in center of gravity and
00:35:38you know kevin was there so kevin tell us about that bike well uh what they did was they they
00:35:47used an
00:35:48idea that elf who were their partners in building uh a line of what people today call high tech
00:35:58um um front ends alternative front ends and honda supplied engines and elf built chassis
00:36:08and the problem was that well one of the concepts that they raised was along the lines of the key
00:36:20to
00:36:20superior motorcycle handling is the lowest possible center of gravity they decided to move the fuel
00:36:28from above the engine to below the engine this was supposed to be hot stuff
00:36:37and why didn't the test riders catch it i saw this bike at daytona it also had
00:36:45carbon fiber fork tubes that were an unspeakable price and they had metal jacketing for the friction
00:36:53surface so they were they were just marvelous things i want unlimited budget wouldn't it be nice i just
00:37:02wanted unlimited budget whatever it is arm eraser magazine stories i want all when people get the big
00:37:09money they're so tired from the effort that all they can think of is olympic-sized swimming pools
00:37:14and uh blonde ladies with cash register eyes and dancers legs and just let me alone i'm i don't want
00:37:24to do
00:37:25anything well uh motocross find me in the shop kevin just bring the budget and find me in the shop
00:37:33making i'll look there yes sir i'll look there um motocross and dirt track have been the most fertile
00:37:43fields in which to grow innovation for suspension
00:37:50now somebody had the bright idea let's compress the front suspension on this motocross bike
00:37:58and hold it down with a latch such that the next time the rider applies the front brake
00:38:06that it will unlatch and let the bike up to the normal ride height in the front
00:38:11the purpose of this because these are bikes with with 10 11 12 inches of suspension travel
00:38:20um it's like tom mix getting on a horse you need to you can't just throw your leg over something
00:38:26that's this tall so they pull the front end down that lowers the center of mass considerably even though
00:38:33the front is still where it normally rides and you get the whole shot you can accelerate
00:38:40harder without lifting the front with the center of mass lower
00:38:48well soon everybody was doing it so it was of no advantage to anyone it moved to moto gp
00:38:56and the wonderful thing about moto gp is that within certain broad limits they do have the money
00:39:08so they uh built the uh whole shot system and they tried it well that was good that was good
00:39:19what
00:39:20about the next turn that we accelerate off of now the bike is at normal ride height
00:39:28why can't we lower it so we can accelerate harder why don't we keep it low all the way down
00:39:35the straightaway
00:39:36so we can brake harder provided that the initial braking is strong enough to transfer weight
00:39:42to the front brake enough to brake maximally so they get to work on this but there's a rule the
00:39:50rule says
00:39:51that electrical or hydraulic means cannot be used oh powered electrical or hydraulic means cannot be used
00:39:59to alter ride height because previous to this there had been an era when had you been able to record
00:40:10moto gp bikes entering and leaving corners you might have heard you might have been able to detect
00:40:17a waveform of little motor humming away little electric motor is rotating the preload ring
00:40:26and raising and lowering the rear suspension in order to gain the advantage of a lower center of gravity
00:40:36lower cg height in certain circumstances the bike has to be high to have cornering clearance
00:40:44it ideally should be lower it should turn into a dragster for acceleration it should turn into a brakester
00:40:51for braking so this was done and i suspect that it um is self-powered that the motion of the
00:41:05suspension
00:41:05pumps up some kind of accumulator and the hydraulic pressure in there which has not been achieved
00:41:13achieved by electrical or mechanical um power sources well the suspension motion is mechanical but
00:41:22you get the idea and there's enough such power available to do these ride height changes
00:41:31um and i asked john cornwell um who recently survived a horrific he and his daughter survived
00:41:40a horrific accident uh with minimal injuries oh my um i asked him so i see pictures i see stills
00:41:51and
00:41:51videos of these bikes but i can't always make out what's going on he said low on the straightaway high
00:41:58through the turns
00:42:02and so for 2027 all this will be banned because they are reasoning everybody has such a system now
00:42:11and so there's no advantage in it it's like when everyone switched to titanium fasteners big deal three pounds
00:42:23all it means is that you've all spent too much money for fasteners
00:42:29well maybe if it's being outlawed kevin we can um make a deal with some team we can call claudio
00:42:35de medicale and say can we see that stuff can we see how it works please can we go to
00:42:40a room with one of
00:42:41these bikes with no body work and look at all the jewels so uh this is at present this is
00:42:52this is the norm
00:42:53and it is also possible to go to the wind tunnel um
00:43:01ducati use uh tunnels that ferrari has i guess or a tunnel
00:43:08and vary the motorcycle's attitude it has wings on it can we perhaps change the ride height at one end
00:43:23upward and the other at the other end downward to reduce the angle of attack so that the
00:43:30aerodynamic drag from the downforce producing wings is at a minimum
00:43:36this is what we hear is done so not only is there up and down but there are also pitch
00:43:43changes that are
00:43:45scheduled into these systems the rules insist that the rider must initiate the cycle for each turn
00:43:54so it's not something that says oh the gps says that we're at
00:44:00position so therefore we must initiate can cycle number xyz
00:44:09well that's what riders need more workload
00:44:15uh when uh when uh when the rules makers were racers it was a long time ago so they're
00:44:22less sympathetic to these crazy kids who've never ridden a bad bike there's the case of
00:44:29of a.j foy i think it was foy who said modern race car drivers have never driven a bad
00:44:37car
00:44:38so they don't know how to compensate for common chassis faults on the track as required
00:44:48i had that same conversation with a a racer who started in the 70s riding you know libertas and
00:44:56other things that are not not easy to ride forks were not figured forks were spindly
00:45:02swing arms were flexible everything the weight transfer weight the overall weight on super bikes
00:45:08whatever and he said yeah these kids you know haven't ridden a bad bike don't know
00:45:13don't know how to compensate and that was the one point i wanted to make and this is how
00:45:16important the rider is as we we've already discussed here but i remember
00:45:22you've you've talked about wayne rainey riding a bike that you know he's obviously one of the
00:45:28greatest talents that's ever been on a racing motorcycle and you could give wayne a bad bike and
00:45:34he would give you a good lap time and part of that is that the percentage of his body weight
00:45:39versus
00:45:39the motorcycle can be moved around and and you were talking about entering the corner
00:45:44exiting the corner and hanging on to the bars and all that the really great guys are putting their
00:45:49bodies all over the place to influence what's happening and if you have a problem where the bike's
00:45:54not doing a certain thing yeah you move your body kevin schwantz when he switched to uh i think it
00:45:59was
00:46:00bush trucks nest nest trucks uh he was you know racing pickups around ovals and stuff and they'd
00:46:06switch to an in-car camera and he would stick his knee out inside the truck because he's entering a
00:46:13corner like it's there man it's like it's already it is written it's not going anywhere so the influence
00:46:20of the rider you know if you have a a jockey-sized rider maybe danny pedrosa has a harder time
00:46:25because he
00:46:26was like 120 pounds or something but uh you get up into 160 pounds and think of the 500 era
00:46:33286 pounds
00:46:35yes you got a big you have a huge influence on that motorcycle certainly do yeah so uh
00:46:44then we we look at dirt track and as i commented earlier the surface is constantly changing
00:46:54so in order to make the motorcycle hook up when it won't you might have to raise it as uh
00:47:01valentino did
00:47:03with jerry burgess at laguna that time to make the bridgestones work um you might have to change the
00:47:12wheelbase length and put a link in or take a link out because both of those things can
00:47:20alter the weight transfer to the rear tire what you don't want is to find yourself rolling into the
00:47:28gas and the back tire wants to go up and kiss the fence so people who really know that business
00:47:40are able to translate the riders are able to translate the rider's complaint or observation
00:47:46a kinder way to say uh into action to correct the vehicle's handling
00:47:55and there are motorcycles on which variable ride height is an option and one of them is harley's uh pan
00:48:05america
00:48:07it has long been known to dealers that every uh dual purpose bike you sell which has longer than
00:48:16street bike suspension travel the owner is going to come back and say man uh it's kind of embarrassing
00:48:25when i get to a stoplight the contortions i have to go through to keep holding this thing up
00:48:31i can fix that for you yeah 35 36 inches more on on motocross bikes they're in that range though
00:48:38they're up to 38 so they they just lower the bike a bit the customer is happy uh he didn't
00:48:46buy the
00:48:47motorcycle in many cases for its uh outstanding off-road performance but because he likes the look of it
00:48:55and that is perfectly legitimate yeah the mechanical ride height change automated uh that has been
00:49:03going through the adventure space is a real boon i mean i'm i'm big i've never had a
00:49:08an issue six foot two 34 inch inseam no problem like put me on a tall bike i don't really
00:49:15it's not an issue but you are a downforce generator yeah yes i am i'm also i'm also good at
00:49:21compressing
00:49:21springs especially now at this point in life but um it is a boon and it's wonderful like when you
00:49:27pull
00:49:28up um it's why that confidence in on the dealership floor the confidence of low seat height that's why
00:49:36everybody all the cruisers low low low people feel happy they sit down it feels 24 inches in some cases
00:49:44yeah yeah on the on the most extreme case yeah so it's it's really good an instance in testing that
00:49:49we
00:49:49had was we did we were doing a large naked bike shootout probably nine bikes and it was circa 2001
00:49:572002 and we had a ducati monster 900 or 1000 i think it was a 900 at that time and
00:50:04what was great about
00:50:04that bike is it had a rod for ride height adjustment and then also spring preload and we were out
00:50:13on the
00:50:13test and i had a lot of seat time on monsters and i knew how the suspension worked and i
00:50:17had a good
00:50:18feeling for how they should be and everyone was slagging that monster for handling like oh it
00:50:23doesn't want to turn it just you know the front's not sticking it just doesn't feel right and i was
00:50:28i got my turn on the bike and i was sitting on it and like man seats really feels low
00:50:34and i rode it
00:50:34i'm like this is not what it should be and i pulled her over and we got out some tools
00:50:39and i found the
00:50:40adjustable wrench and that it's just a long rod with opposite threads so that when you screw it in one
00:50:45direction it spreads the rod longer and when you sprint the other scores it down well it had come
00:50:50from a dealer turnbuckle yeah we yeah we needed the bike there wasn't one available like you know it's
00:50:57like here here's one from the dealer so we got one from the dealer but the dealer had taken all
00:51:02the
00:51:02preload out and compressed the ride height at the rear to the lowest setting so it was a really low
00:51:07good
00:51:07feeling wow this is great it fit low center gravity and it's i can put my feet flat on the
00:51:12ground
00:51:12wonderful but it didn't work dynamically and on the side of the road you know above anza borrego
00:51:18wrench wrench wrench take the lock nuts off extend it put it back together it was transformed and i mean
00:51:24that was the super bike frame essentially that was the it was great that's what i'm getting at it was
00:51:29great and you know so it's a vote for you folks out there with with motorcycles measure your sag do
00:51:35that
00:51:35stuff don't just accept what you get um if you buy a bike you know get active and mess with
00:51:42your
00:51:42suspension and and see how life feels if it improves doug chandler uh was well known for
00:51:49wanting a steep rake angle and you get that um on an adjustable bike by saying you want it the
00:51:57mechanics take out a bunch of stuff from the steering head put in other stuff and there you are but
00:52:05that um situation didn't occur until later so what you did was you raised the back of the bike
00:52:12and possibly lowered the front as well thereby reducing the steering head angle and um all these
00:52:20things have a bearing on what's going on moto gp riders say that they use the rear brake
00:52:29seventy percent of the way through corners i'd like to have more discussion on that
00:52:36but um i did work with a rider uh ron pierce who he was riding the wild and crazy kr
00:52:43750 kawasaki
00:52:44water-cooled triple and he said the brake is a quicker way to control engine torque than the throttle
00:52:52oh yeah dirt trackers uh always yeah oh yeah i mean anybody you know you name it yep and because
00:53:01the
00:53:01uh ability of that water-cooled engine to pull strongly on the chain was uh so great
00:53:11on one occasion the um rear disc it was a i think it was a an ap disc was cast
00:53:19iron got so hot that it
00:53:20melted all the grease out of the wheel bearings and i had to put an insulator between the brake disc
00:53:25and the
00:53:26hub but uh the lesson here is that these problems have been solved by people thinking about the
00:53:35problem well let's see what is causing this what how can we get at it let's take the problem apart
00:53:43so
00:53:43we actually understand it rather than just being the guys that say oh garlitz is doing this let's do it
00:53:52there's a lot of that in the world and that is why the late great albert gunter
00:54:00told dick man don't ever imagine you're going to beat those guys using what they're using they've
00:54:09had it a lot longer than you have you've got to have an edge something that only you have and
00:54:18that takes thought
00:54:20you have to come up with something and extraordinary writers like uh freddie spencer kenny roberts and
00:54:27and others did just that um when
00:54:34uh mark uh marquez did his two years in moto two moto two has spec engines so forget tuning the
00:54:46engine
00:54:47it essentially has spec chassis because when the calyx came out they worked well everybody bought a calyx
00:54:55and so what is he left with as an edge
00:55:01there were plenty of daring people who could really throw her in his edge was tire management
00:55:11when he got to moto gp in his first season i think it was the german grand prix
00:55:16uh his tire drop occurred laps later than that of valentino rossi laps later than that of uh lorenzo
00:55:29well impressive because he learned how to get more from the tire without progressively destroying it as much
00:55:42using the tire yes it does destroy it but the rider can have such an influence on how fast that
00:55:49happens
00:55:51so huge yeah i mean i think i think back to um uh jim allen in the dumb lop truck
00:55:58and looking at the
00:55:59wear patterns of a rider who broke who was an incredibly hard breaker but also was constantly
00:56:05ruining his tires and pushing the front pushing the front using the front just mash yeah just mashing it
00:56:12out and he would just he wouldn't have grip he'd go incredibly fast he'd be at the front he could
00:56:16lead the race but he couldn't finish winning the race yeah and um man it's just it's so much like
00:56:22that and i what you were saying about having their their own recipe having a talented rider like
00:56:28obviously these people see a completely different plane of what's going on the sensitivity to the
00:56:33tire you talked about uh riders talking about the noise that a tire makes i know when the tire is
00:56:38changing because i it sounds different not only is it going to feel different obviously you get
00:56:43sometimes you get vibration when it's about to chunk you know there's all the things that
00:56:46happened but there was a sound and you had i remember you had said to someone in the tire
00:56:52business like hey you ought to put some uh some microphones back there and then there's
00:56:57funny old kev coming up with the what the hell are you talking about buddy why don't you go have
00:57:02a
00:57:02sandwich you know get out of my life well uh kenny's contribution was to act on what everyone knew
00:57:12that motorcycles are lousy at turning and they're great at acceleration because two wheels an engine
00:57:20and a place to sit whereas cars have all this extra stuff they use one set of tires for going
00:57:27around
00:57:27right-handers and another set of tires for going around left-handers what kind of a craziness is that
00:57:33uh so uh these are these are the innovators and so it is with with chassis and suspension setup
00:57:44and what have you um the reason that people talk about moto gp critics talk about it being a tiresome
00:57:52procession is because um the riders are all good at it
00:57:58uh and close racing is not achieved in any other way than by scripting
00:58:08or the occasional accident like some memorable battles between for example wayne rainey and um kevin
00:58:16schwantz where they they went ding dong paint transfer time uh for long periods of the race rossi was always
00:58:26good at throwing something out right the creativity of valentino rossi uh i think of 2009 at uh barcelona
00:58:34catalonia where he does the you're you're at catalonia you're going this downhill and it's in a place
00:58:41where you wouldn't you come out of a turn you're kind of going into downhill and then it's a a
00:58:45fast
00:58:45right onto the front straight and catalonia's front straight is pretty long and he passed between
00:58:50the two corners the final corner and that corner beforehand down and he just squirted by
00:58:56lorenzo it was it was shocking and unexpected and it is it is wonderful to see that we we like
00:59:02that
00:59:03creativity tactics yes yeah it's it reminds me of of nick einatch what nick einatch said once at a
00:59:11school he was talking to a racer i was at the school he was talking to a racer he was
00:59:15coaching
00:59:15as part of this school and what he said was i can only i can only tell you as much
00:59:22as what would
00:59:23help you win second in the 250 grand prix championship fully realizing and fully knowing
00:59:30that that's every every tool that he could apply at that time that's the best he ever got racing in
00:59:36his career at in the most competitive thing and that was the those were the tools available and
00:59:42it's up to the next person the guy he's coaching like i can get you here but
00:59:47use these tools to to find first it's we all have to admit where we are and then try to
00:59:55be creative as we can so
00:59:58and of course the way handling is affected by tire life the need for extended tire life is that
01:00:07there are people who set up their bikes the way they would set up a dirt tracker they scrub off
01:00:14speed with
01:00:14the front and the front is not destroyed in the process at such a fast rate but if you try
01:00:20to
01:00:20ride that way on pavement your front end your motorcycle's front tire will look like somebody
01:00:26went at it with a with a coarse wire wheel it's just strings hanging off the rubber strings
01:00:35so uh having a machine that's well set up to use its tires minimally very desirable well and the
01:00:43rider hasn't has an influence as you've pointed out i i was terrible on fronts at willow springs
01:00:48because i was always a person who rode the front and then at willow you have all these incredibly fast
01:00:53rights especially you know basically from from six to the front straight you're just and i was brutal
01:01:01like i came in on a ducati and experienced endurance racer you know came over and looked at my front
01:01:08tire and
01:01:08like feel felt the tire and looked at me and i was i just wasn't using the rear enough you
01:01:14know i wasn't
01:01:14i wasn't balanced particularly at that time i was uh better on the front than the rear like my exits
01:01:20were
01:01:20not that good i learned i got better but uh smoke a front buddy especially that back then i mean
01:01:28the
01:01:29evolution of tires for what we get to test with i mean in nine laps you could wreck a tire
01:01:35you know in like
01:01:362000 1998 you could wreck a tire in seven laps at willow just destroy it and then now you could
01:01:43go
01:01:43to almost any track and throw your pirellis or bridgestones or or whatever the compounding is so
01:01:49good and the wear resistance resistance to heat cycling if you have tire warmers and you can keep
01:01:54your tires from heat cycling while you're at the track boy you get a lot of life out of these
01:01:59things
01:01:59and they're good they're good for a long time end of the day they're good it's i think one of
01:02:05the
01:02:06great one of the crucially important things there has been the uh adoption starting in 1992 of uh silica
01:02:16reinforcement in the tire tread compound in the past um
01:02:23um well in the early days they found that adding certain things to the tread compound made the rubber
01:02:30last longer and the one that worked best was not the zinc oxide that made so many early early tires
01:02:39white it was carbon black and um that's why tires were were black forever they still are black but now
01:02:52grading off to gray because silica is not black silica bonds to rubber chains chemically
01:03:02making the tire much giving it more tensile strength so that it broke the the old um
01:03:12what do they call it the magic triangle of uh tire life tire grip i forget the third one
01:03:20um but the great tensile strength conferred by silica has made it possible for um
01:03:29people to break in a in a in an apparently insane way because the the curve of tire grip versus
01:03:38tire load
01:03:40doesn't hook over down here now it hooks up hooks over up here because of that higher tensile strength
01:03:50so um racing does improve the breed but people love to argue about it and i'll let them
01:04:02well excellent thanks for listening folks we're really glad to have you here as a subscriber uh we
01:04:08appreciate that very much um thanks for joining us i do i did get a request for my dog
01:04:14someone request champ come here lunch
01:04:20so my dog has barked variously in in other programs and she's come up and demanded attention before
01:04:29i see a nose i see a paw there she is there we are that's champ she's a real sweetheart
01:04:36and
01:04:36she's very quiet and very good dog this time so thanks champ thanks for being awesome here's another one
01:04:43here's another one bye um thanks for listening folks thanks for joining us so that was champ and um
01:04:49we'll catch you next time
01:04:50you
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