What do Rake, Trail, Wheelbase and Offset mean for your motorcycle and how it turns, stops, accelerates? Are there magic numbers that result in "good" handling? What is good handling anyway? Technical Editor Kevin Cameron and Editor-in-Chief Mark Hoyer talk about motorcycle handling and the fundamental improvements that have made new bikes so good.
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Read more from Cycle World: https://www.cycleworld.com/
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SportsTranscript
00:00:00This is the CycleWorld podcast.
00:00:01Welcome back.
00:00:02I'm Mark Hoyer.
00:00:03I'm the editor in chief.
00:00:04I'm with Kevin Cameron, our technical editor.
00:00:07The topic this week.
00:00:10It's kind of spacey.
00:00:11Well, it's not spacey.
00:00:14We all know it when we feel it.
00:00:15What is handling?
00:00:16Well, what is good handling?
00:00:18What is handling?
00:00:19Um, good handling, you know, broadly, Kevin, you said good handling was, um,
00:00:25asking the motorcycle to do something and having it do what you want.
00:00:30And, uh, that's a, that's a pretty good definition because what we ask a cruiser
00:00:36to do is vastly different than what we ask a sport bike to do, which is also
00:00:40different from what we ask an adventure bike to do, et cetera, et cetera.
00:00:44You can go down the line standards, sport standards.
00:00:47Are there magic chassis numbers that just work?
00:00:51What's, uh, where do we begin on this one, Kevin?
00:00:55Well, there are always good starting points.
00:01:02And that's why, uh, newcomers to a field, um, say you decided to produce an
00:01:09adventure bike, you buy the existing machines and you draw conclusions from
00:01:16the way they're designed in order to inform yourself.
00:01:20And in that way, yes, there are good starting points.
00:01:24For each field, you will find, for example, that a large tour bike may have,
00:01:31uh, the fork inclined at a 30 degree rake angle with a fair amount of trail,
00:01:39like four and a half inches.
00:01:41If you step over to another part of the sales floor, you find what's left of the
00:01:48sport bike, uh, phenomenon.
00:01:51Maybe, uh, an unsold 600 is sitting there and it's steering head angle.
00:01:57It's a rake angle, um, is a lot steeper, more like 24 degrees.
00:02:05And it's trail, uh, is somewhere between four inches, which is the usual.
00:02:11And in earlier times, it might be as short as 3.7 inches.
00:02:17Well, and then we have outliers such as Eric Buell.
00:02:22That's the Buell.
00:02:23And, and I want to say XB9, XB12.
00:02:26Those were in the range of 21 degrees of rake and 3.3 inches of trail.
00:02:35And they were not head shaking death machines.
00:02:39Yeah.
00:02:40Well, one of the reasons why, uh, years ago, all motorcycles had fairly
00:02:47substantial rake angles in large trails was that their chassis were not stiff
00:02:52enough to be stable with those numbers.
00:02:59Now you look at a Bonneville bike or a drag bike, and you can see the front
00:03:03end is raked out so that when you turn the bars, you're mostly tilting the
00:03:08wheel this way and not steering it.
00:03:12Um, and that slows the steering way down.
00:03:16And it's still a practice in those high speed disciplines.
00:03:21But, um, you could not, for example, give, uh, your classic
00:03:26Triumph Bonneville a 21 degree steering head angle and 3.3 inches of trail
00:03:32because it would not be stable.
00:03:36I can't imagine, you know,
00:03:38my pre-unit was far more relaxed than that.
00:03:42And it would still be a little, uh, you know, rain grooves were a nightmare.
00:03:47Sure.
00:03:49So, um, what we can say about these numbers is that they are pragmatically
00:03:57arrived at, uh, there is no giant electronic brain in the sky, possibly
00:04:03up in the cloud that can tell us what it should be.
00:04:08So this, for this, we have road testing and for, uh, racers.
00:04:15A lot of these things are a matter of personal style.
00:04:18If the rider feels that there's best communication with the motorcycle,
00:04:24with, with these numbers, that's what they'll give him.
00:04:28So, uh, well, let me weigh in on that because the CBR 900 RR, um, was, is a
00:04:40good example of going for what, uh, Ted Albaba said was the bigger circle.
00:04:48He wanted a sport bike that had leader-class power, agility of a 600
00:04:53and had ease of riding, light steering.
00:04:56So it had a very short trail in the, uh, early models and then extending, uh, in
00:05:021998, that was the year they fixed the trail and they made a longer trail.
00:05:07It still had a 16, uh, 16 in front wheel.
00:05:10The rolling diameter to the tire was very close to a 17.
00:05:14Uh, but the rim was smaller and, um, Honda was very good in those years
00:05:19about letting us ride the motorcycles back to back year, year versus year,
00:05:24which a lot of manufacturers didn't.
00:05:25So we got to go out on previous year model, short trail, new model, longer
00:05:30trail, and they felt really similar up to a certain point to when the short
00:05:38trail information stopped flowing to my hands through the handlebars, because
00:05:44the, I think that the length of the lever, the trail pushing back through
00:05:48the bars certainly was, uh, was different and, and less, less informative.
00:05:54So you pushed hard and suddenly there wasn't the information you
00:05:58were looking for anymore.
00:05:59Whereas with the long trail, you had it.
00:06:02And that loss of information is what the MotoGP rider is talking about.
00:06:07When he says the front end closed because you're applying, uh, control
00:06:15pressure on the bars and the rubber is saying, uh, I don't know about this.
00:06:21Then as you approach the grip limit, that self-centering feeling that you
00:06:27feel in the bars goes away just as you are speaking and the international
00:06:32symbol for this is, and that's closing, losing front grip altogether.
00:06:42This is of course, talking about being in a corner, not something that's
00:06:45happening while you're, uh, going up the white line world.
00:06:51But, uh, racing is like that.
00:06:54It, it is the place where the, the, the sharp end is sharpest.
00:06:59And that's why a lot of what is known about motorcycle handling
00:07:04comes to us from racing.
00:07:07Uh, there were really two big revolutions in motorcycle handling.
00:07:12Uh, the first one was the, uh, suspension and wheel suspension
00:07:21travel revolution of the 1970s.
00:07:25Longer wheel travel is advantageous because the amount of energy that a
00:07:30suspension can absorb is proportional to travel squared.
00:07:37So back in the bad old days, when we had black painted girling shocks on
00:07:43the back with three inches of travel and stiff springs, uh, we might need
00:07:50to stop fairly often on a long trip.
00:07:53But from 1974 on, uh, a conduit was opened from off-road bikes where long
00:08:03travel and its benefits were discovered through racing to production bikes.
00:08:10And longer travel allowed the use of softer springs and softer damping.
00:08:16So that, that old time sports car advice, stiffer is better.
00:08:22Uh, while you're vibrating and chattering off the road, because you can't make
00:08:30stiff sprung wheels follow the bumps.
00:08:34Uh, that's, that's nonsense from the past.
00:08:37We have to give that up.
00:08:39Goodbye.
00:08:39May I, may I quote the great Alan Gerdler?
00:08:42Yes, please.
00:08:43The only way to make suspension work in the 1970s was to not let it.
00:08:49Yes.
00:08:49Yes.
00:08:51So yeah, it was, you made it stiff because you know, it was sort
00:08:55of in the ballpark that way.
00:08:56And if you only had three inches of travel, you know, Harley
00:08:58now has touring bikes.
00:09:00Three inches of travel is not allowed to work with, but Harley Davidson
00:09:03is looking for that on the baggers.
00:09:05So they're looking for that slammed.
00:09:07Look, they're looking for that low look.
00:09:09And their engineering is often geared toward how do we give the customer what
00:09:14they want visually that feeling, walking up to it, having the low seat, all the
00:09:19stance, you know, stance is important.
00:09:22Um, choppers.
00:09:23It's a stance thing.
00:09:24It's, it's, it's a feeling.
00:09:26It's not, we're not, uh, you know, we're not trying to set a lap time.
00:09:30So three inches of travel is not a lot, but their chassis development folks
00:09:36have done a remarkable job of working with that.
00:09:39They even have ones that are two or less, you know, when they, they say, oh,
00:09:43we've increased our suspension travel 50%.
00:09:46That was two inches to three inches party in the engineering house.
00:09:50Right.
00:09:51I mean, honestly, but they've done a remarkable job of working within
00:09:56that limitation.
00:09:57But when you have, you know, five inches of travel or six inches of travel,
00:10:01you don't have to confine all the work to this short area of space.
00:10:06You can, you, you can expand the work over many more inches.
00:10:10So you can make that compliance work for you.
00:10:13And it's really, uh,
00:10:16the second revolution, uh, took place for street bikes in the 1980s and it was
00:10:21structural.
00:10:23And where that was coming from was from road race, where they found that they
00:10:30couldn't get best results from the tires unless the chassis was a lot stiffer.
00:10:36Now, of course, today there's all this talk about engineered flexibility.
00:10:40That's a separate issue.
00:10:42What we're talking about here is the bad old days.
00:10:46I walked up to a Triumph, parallel twin, classic era, let's say 64 Bonneville.
00:10:55Held the front wheel between my knees and I could turn the bars many degrees
00:11:00in either direction and it wouldn't necessarily snap back all the way.
00:11:05It would stay where I put it.
00:11:07I'll put it over here.
00:11:09The fork tubes were slipping in the fork crowns.
00:11:13The fork tubes were little.
00:11:15They were 34 millimeters and axles were tiny 14 millimeter front axle or 15 and
00:11:24a 17 millimeter rear axle.
00:11:27They were solid, but the material at the center doesn't contribute a lot of
00:11:32bending strength because it's basically a wire.
00:11:36You want the material out at the largest radius, which is why modern bikes have
00:11:41large tubular axles.
00:11:44They have larger fork tubes.
00:11:48Vintage racer, recently talking to a vintage racer who spent a lot of time on
00:11:52Yamaha XS 650 is the parallel twin of the ancient days.
00:11:56Yes, early 70s, mid 70s and into the 80s.
00:12:01Turns out you don't use the early frame because the wheelbase is too short and
00:12:04all the weight is on the rear.
00:12:06But in talking to him, so you can't you just you in vintage racing Arma, you
00:12:11can't just go get an R6 front end and bolt it to your your Yamaha.
00:12:16They were searching for a feeling in a period of time and trying to make it
00:12:21practical.
00:12:23He said one of the greatest things that he did for the front end feedback and
00:12:27stability on his XS 650 was to knurl the fork tubes where they go in the
00:12:34clamps.
00:12:35So he put them in his lathe and he knurled right where the triple clamps
00:12:40would go on where they grip it where they grip it.
00:12:43And he said the amount of feedback and the positivity of the front wheel was
00:12:47through the roof compared.
00:12:48I mean, we're talking about a pretty low bar, but that's what you know.
00:12:53That's that's the thing.
00:12:54That's the poetry within the form part of making something work that maybe it
00:12:58wasn't designed with your use in mind, your end use such as vintage racing.
00:13:04I walk away from that 64 Triumph Bonneville.
00:13:07And over here is a modern parallel twin KTM or Yamaha or any of the modern
00:13:16idiom.
00:13:18Put that wheel between your knees take hold of the bars and you feel like
00:13:23you're trying to twist a monolithic steel part.
00:13:28It feels like when you do when you apply pressure at the bars it arrives
00:13:35right now at the footprint.
00:13:38You don't have rubber mounted bars that are going squidge as you apply torque
00:13:43to them and then fork tubes that are going eat as they slip in the fork
00:13:49crowns and they are not skinny little fork tubes that are quite spaghetti
00:13:54like in their ability to transmit your command down to the tire.
00:14:01So that was a that was a revolution but you have to look carefully for it
00:14:07because the Bonneville had an axle it had fork tubes.
00:14:12So does the KTM or Yamaha or Aprilia parallel twin of the present moment?
00:14:21Really big things happened in chassis during the 1980s production bikes.
00:14:27One of the first was Honda's Interceptor of 1983 which had a square tube
00:14:34steel frame and it was a lot stiffer than what came before.
00:14:44It was also heavy but so was the frame that it replaced and Honda built those
00:14:51Interceptors as homologation specials.
00:14:54We'll just make a few to make it legal for us to run this in AMA Superbike,
00:15:00but for some reason at that moment people were ready for a more responsive
00:15:07motorcycle and they just disappeared from showrooms gone.
00:15:12Where can I get one?
00:15:13I've got to have well there aren't any and so the message was sent to the
00:15:20industry handling is something that people want.
00:15:26So it wasn't long before all that welding and whatnot was replaced by the
00:15:34twin aluminum beam chassis or by other stiffer structures.
00:15:40Now, I was at Ducati once and I spoke with engineer Preziosi.
00:15:47And he said the motorcycle designers job is mostly done for him because you
00:15:55know the wheelbase so you clamp a pair of wheels on your building table at
00:16:02that wheelbase, you know that there has to be a swing arm of somewhere in the
00:16:07weight range of 24 to 20 inches long.
00:16:11So you put that on, you know, what its droop angle is going to be
00:16:15approximately and why do we know the droop angle?
00:16:20Because we all have a copy of the Ohlins recommendations on how to set up the
00:16:27anti-squat in the rear so that when you gas it your car doesn't behave like an
00:16:34old Buick and settle in the back and rise in the front looking like a barge
00:16:39that's trying to plane.
00:16:41The angle of the swing arm and the angle of the chain pull are kind of at odds.
00:16:46Yes.
00:16:47And so the chain pull is trying to is not trying to extend the suspension
00:16:51trying to extend the suspension, but only so much as to counteract what's
00:16:56happening with weight transfer.
00:16:57Like you don't want to overdo it.
00:16:58You don't want to have it, you know, weigh down and have all the force and
00:17:02have no compliance.
00:17:05And right can be a matter of one or two millimeters in the height of the
00:17:11output sprocket.
00:17:12So the output sprocket, you know, where that goes, you know, where the bars
00:17:16go, you know, where the fork angle will be approximately.
00:17:21And if you have an engine, it's got to sit there with its sprocket in this
00:17:25place.
00:17:26Then he said.
00:17:28Once all those things are in place, you build a bracket to hold it all together
00:17:32and that's called the frame.
00:17:33And it turns out that Tamburini built that trellis frame for Ducati and the
00:17:42peculiar thing about that frame.
00:17:45I looked at the one on their replica racer V4, you're looking at the front of
00:17:54the frame.
00:17:56And there is no diagonal preventing the steering head from moving.
00:18:01Preventing the steering head from flexing all those pieces of pipe
00:18:06laterally.
00:18:09Nothing.
00:18:11And that's why when I said to Colin Edwards at one point, this was right
00:18:19around 1990, said the Ducatis wallow like crazy in the corners.
00:18:25And he looked at me and he said, yeah, they wallow but they dig in and they
00:18:30go around the corner.
00:18:32And what he was talking about was that flexibility in the front allowed the
00:18:36front tire to be disconnected from the mass of the engine so that when it hit
00:18:44a bump, it would simply flex upward and flex back downward.
00:18:50Right, he's talking about it at full lean, like when you're completely leaned
00:18:54over.
00:18:55Yeah, when you're at full lean, the fork is not prone to compressing when you
00:19:01hit a bump.
00:19:01Yeah, the fork is irrelevant.
00:19:02It's at the wrong angle to operate in this case.
00:19:06So what Tamburini's chassis did was it provided some lateral give to allow the
00:19:15front end to remain hooked up.
00:19:17And the antithesis of that front end flexibility, the old one was the RC30
00:19:25which had this beautifully flowing structure around the steering head.
00:19:31It looked massively rigid.
00:19:33It was.
00:19:35And riders would find, just like Casey Stoner talking about the Ducati
00:19:43carbon fiber frame of 2009.
00:19:49There you are in the corner.
00:19:51You're on the computer records later show that your variables are exactly
00:19:57what they were for the last three laps, but you're on the ground.
00:20:02No warning.
00:20:04Suddenly the motorcycle's horizontal.
00:20:07And what's going on there is that the front tire, which is rigidly
00:20:12connected to the rest of the motorcycle through that wonderful steering
00:20:18head, is skipping across the tops of the bumps.
00:20:22And when the front tire gets air in the middle of a corner, you jump sideways.
00:20:27It's called, the British used to call it stepping out.
00:20:32And that means that you have to go slower.
00:20:38Because you have that extremely stiff front end.
00:20:43The reason that the rest of the chassis in other directions, such as longitudinal
00:20:48bending or torsion, is that torsion allows the wheels out of plane, which
00:20:57causes gyro precession forces that are quite upsetting.
00:21:02Norton Model 8, 1954.
00:21:07Garden gate frame, you know, all the old stuff.
00:21:09That's the thing.
00:21:10The relationship, stepping back in vintage biking, for me, being present and
00:21:15alive at the moment, I had a 1937 KSS Velocette.
00:21:20So it's an overhead cam 350 Velocette with a girder fork and a rigid, no
00:21:27suspension in the rear.
00:21:28I mean, not entirely true, a sprung saddle.
00:21:31But the frame, the rear axle and the steering head were pretty firmly connected
00:21:37on that motorcycle.
00:21:38And it was beautiful to ride on a smooth road.
00:21:40Jump to my 1954 Velocette.
00:21:42Sorry, I know I'm talking Velocettes, but I got a lot of seat time.
00:21:4754 Velocette swinging arm has a single vertical tube.
00:21:53Braced to it is basically like a very narrow pivot where the shaft for the
00:21:59swing arm goes through.
00:22:01And then the swing arm legs clamp with a single bolt each onto that crossways
00:22:08pipe and then the shocks go up to the frame and the shocks are, you know, it's
00:22:14not a particularly robust loop.
00:22:17There's not, there's just a lot to move around.
00:22:20Now Velocette swing arm bike actually for the time handles pretty good, but
00:22:24compared to the rigid bike, the steering input, the stability, the compliance is
00:22:30better, but the bike wants to, wants to go in several directions at once.
00:22:36Less so than some of the, because the wheels are doing all this.
00:22:39And if you trail brake on the front only on that motorcycle, the rest of the chassis
00:22:45stacks up on the bike and it puts in all kinds of really weird information.
00:22:50So you actually use the rear brake to keep the wheels in better alignment.
00:22:55I mean, it slows you down a little bit faster because we're talking about
00:22:58watch band sized brake linings, you know, the width of your watch.
00:23:03Excellent.
00:23:04Yes.
00:23:05But you have to use both brakes to keep the wheels in alignment.
00:23:08And what you're talking about with Ducati is that sideways compliance
00:23:11keeps, keeps the relative parallelity of it.
00:23:17Yeah.
00:23:17Keeps the front wheel parallel to the rear wheel, but allows it to move
00:23:21laterally so that you're there in the corner.
00:23:23The bump is doing this, but it's not doing this.
00:23:28And at the back, the swing arm is not wagging from side to side when it hits
00:23:32bumps.
00:23:33Kelker others spoke about Honda's RC 161, which was a 250 that he was given
00:23:40when he was riding in Australia.
00:23:43And it had that frame that you described where there's a sort of a backbone
00:23:48and there's a tube welded into it.
00:23:50And that's the swing arm pivot.
00:23:52So it depends on the torsional stiffness of the seat, what they used
00:23:56to call the seat tube.
00:23:58And that won't do.
00:24:01I mean, you can ride around perfectly well on that as long as you're
00:24:07gentlemanly about it.
00:24:08But if you want to press on, you're going to discover that there are
00:24:11limitations built into that structure or lack of structure.
00:24:16Yeah.
00:24:16I mean, you know, the, one of the reasons we test bikes and we go to the
00:24:19drag strip and we just ride the daylights out of them is that almost
00:24:23everything's pretty good at 60%.
00:24:25If you're going at six tenths, almost everything's pretty darn nice, but
00:24:29it's when you start hammering it, that, that you find those limitations.
00:24:33It's like with the CBR, with the short trail, pretty great bike on the
00:24:36street, like back to back with the longer trail model, not, not so
00:24:41different, but as soon as you hammer it, you're like, whoa, big difference.
00:24:45And that's what's so great.
00:24:46That is the, the key with racing is we're rushing around.
00:24:50Why are we rushing around this track?
00:24:52Well, I don't know, because it seems like I got to, but in doing that,
00:24:56you're, you're looking for every possible way to go faster and faster.
00:25:00And you're asking more and more and you're finding, you're finding out
00:25:05where the flaws are for that.
00:25:07It turns out that the, the first implementation of countermeasures is
00:25:13expensive because it's come from the prototype shop.
00:25:15You're, you're, the racing activity gets a bill for a hundred thousand.
00:25:19What's this?
00:25:20But those ideas go over to production and they discuss how they can
00:25:27manufacture these advances at prices that people can afford to pay.
00:25:33And that's the wonderful thing about production engineering is you can
00:25:37take some carbon fiber, titanium, aluminum, titanium, titanium, titanium,
00:25:43carbon fiber, titanium, beryllium monstrosity in there and say, well,
00:25:48it's working.
00:25:49We got it working pretty good and they can make it out of aluminum and
00:25:54steel and still achieve an advantage and improvement.
00:26:00So overall, the structural revolution, which took place in street bikes in
00:26:05the 80s, moved things forward from 1960s level chassis, suspension, and
00:26:13tires to the next step.
00:26:18And we had the Honda Interceptor, the Ninjas, the Seikas, and motorcycles
00:26:26that had much higher capability when you pressed on.
00:26:32And a lot of people did.
00:26:34Sport bikes were hugely popular for decades.
00:26:39And then people got tired of them and they're gone now.
00:26:43Well, they're not gone, but they're less there than they used to be.
00:26:48They're subtle now.
00:26:49Yeah, there's good stuff happening and we still have R1s and M1000s and
00:26:56Ducati V4s and there's still some good action there.
00:27:00When you were describing all of this, the chassis revolution of the 80s,
00:27:04I've been spending quite a bit of time thinking about the BMW of Udo
00:27:10Giedel and Schuster and Todd Schuster.
00:27:13And you know, chassis rigidity was so important that they put a strut from
00:27:18the steering head to the swing arm pivot and they passed it on both sides
00:27:23and they passed it through the carburetor bell mouth because it was that
00:27:26important to fit because they needed intake length.
00:27:30And it occurred to me as we had this discussion, that was a twin loop frame.
00:27:34It was very much like a Manx featherbed, you know, twin loop, pretty good
00:27:39reinforced steering head, but not reinforced enough.
00:27:42And essentially what they were doing is making it a twin spar.
00:27:45They were running.
00:27:46They were just running the spars down the side and the bike.
00:27:48I'm going to race a bike at ARMA, which by the time this comes out,
00:27:51I will have raced, but it's a BMW built in the spirit of the Giedel bikes
00:27:56and it's got that brace on it and it's a beautiful handling bike.
00:27:59There is some flexibility in the overall package, but it's flexible
00:28:04in a way that's predictable and not terrifying.
00:28:09There are also mass properties to be thought of and one of the things
00:28:15that people have discovered is that the less mass there is on the
00:28:20steered part of the motorcycle, the front wheel brakes and fork and
00:28:27crowns, the less mass there is, the more resistant the front end is
00:28:33to the oscillation that we call wobble, which some people encounter
00:28:38if they're going 30 or 40 miles an hour and they think, oh, I didn't
00:28:42fasten my gloves.
00:28:43You take your hands off the bars and it starts.
00:28:46Oh, I'll just put my hands back here.
00:28:51That is made worse by such things or maybe made worse by such things
00:28:57as a handlebar mounted windscreen or trying to carry load up front
00:29:02on the rotating the steered assembly like bicyclists do.
00:29:07Bicyclists don't get to a speed where it's a problem.
00:29:12Well, there was that Bates Fairing in the 70s that had a trunk in
00:29:17the front and you could put stuff.
00:29:20This is crazy.
00:29:21We have ads in the old magazines of that and I just thought, man,
00:29:24what a terrible place to put a load.
00:29:28The other thing about the mass on the fork that I think is important
00:29:31and I know this from talking to the chassis development folks at
00:29:36Indian, they felt duty bound to produce the first chiefs with the
00:29:41valance fenders.
00:29:44And imagine the amount of mass that you're adding to the front end
00:29:46when you must make it steel because we will accept nothing less.
00:29:51Yes, you must make it steel and it must be big and swoopy and valance
00:29:57and so you're adding all of this mass.
00:30:00I'm like, how did you guys get this thing to steer because it's
00:30:02steered really nice.
00:30:04We concentrated the mass on the axis of rotation as much as possible.
00:30:10So that's your bowling ball and ladder analogy that yes, it is.
00:30:13You ought to bust that out right now.
00:30:15Okay, get your ladder, buddy.
00:30:18Used to be that there was in the magazines, what are magazines?
00:30:22Honda's Red Page, which was a exposition on some technology of theirs
00:30:30and I remember that there was one entitled mass centralization.
00:30:35Well, a motorcycle is fun to ride in a straight line, but there's other
00:30:40experiences to be had from rapid turning and maneuvering and what
00:30:44have you, as we all know.
00:30:46And a motorcycle, in order to be responsive, needs to have all of its
00:30:53mass concentrated close to the center of mass because imagine trying
00:30:59to go around the corner carrying a 24-pound cannonball, which is
00:31:04five and a half inches in diameter, like that, versus a 10-foot ladder.
00:31:13The ladder is quite a thing.
00:31:16You exert force to get it swinging, then you have to exert another force
00:31:21to stop the swing.
00:31:23And the reason that it behaves differently from the bowling ball is
00:31:26that there's mass out there on a lever arm and it's moving quite rapidly
00:31:32as you swing it to change direction.
00:31:34And so motorcycles, you don't stop wheelies on your Ducati by mounting
00:31:42the battery up on the inside the front fairing, even though in terms
00:31:49of an anti-wheely device, it looks attractive.
00:31:53It also makes the motorcycle, it is contrary to mass centralization.
00:31:59So the rider, the fuel, and the engine, and all the electrics and all
00:32:06of the appurtenances are generally located close together in order
00:32:12to maximize the rapidity of response of the motorcycle when you want
00:32:18to rotate it, either this way or in yaw.
00:32:25So that's the basis of mass centralization's advantages.
00:32:31There's another effect, and I alluded to that by saying when we talked
00:32:35about the Valance Indian, traditional Indian fender and its mass.
00:32:44The same thing is true of the rear end of the motorcycle.
00:32:47A motorcycle is two casters, a short one at the front, whose trail
00:32:55is the trail that you have, and the long one at the rear, its arm
00:33:01is the wheelbase.
00:33:03And you'll notice that a lot of European tourists load with a tank
00:33:09bag. They don't pile stuff up on a rack in the back of the motorcycle.
00:33:15Well, in the early 60s, the Japan Society of Mechanical Engineers
00:33:19did a bunch of testing on motorcycle stability, and they found that
00:33:25moving the engine and the rider and other things forward made the
00:33:31motorcycle more stable.
00:33:33What you don't want in questions of stability is to have a large
00:33:39mass moving through, oscillating through a large distance.
00:33:42So if you put the 24-pound cannonball on the lower part of the
00:33:48rear fender, it's going to chase your motorcycle quite a bit.
00:33:52Yeah, the top trunk, the classic top trunk, you put a big load in
00:33:56the top trunk on, you know, many, many different kinds of motorcycles
00:34:00and you'll get what a lot of times what they would call the decel
00:34:03shimmy. So you roll off and it starts to wobble.
00:34:08I believe in the days of vacuum tube police radios, there was a
00:34:12similar effect. Great big thing on the luggage rack.
00:34:18So that's why if you look at any modern motorcycle, you'll see that
00:34:25the engine is really friendly with the front tire.
00:34:29And the reason is that you're concentrating the mass of the rear
00:34:36caster, that is most of the motorcycle, closer to the pivot rather
00:34:41than farther away from the pivot.
00:34:45Back when Honda was winning all kinds of Grand Prix races in the
00:34:511960s with their high revving air-cooled 5s, 6s, 4s, a 50cc twin,
00:35:02they put the engine in the middle of the wheelbase.
00:35:08And because it seemed to make some kind of intuitive sense, it worked
00:35:14fine until they got to the 500.
00:35:17And the 500 wheelied easily and when Mike Hale would accelerate with
00:35:28Agostini right with him, the bike would sometimes weave quite vigorously.
00:35:35That's the swinging from side to side of the rear caster.
00:35:39And he had a hard time keeping up because Agostini's MV had the engine
00:35:47farther forward and Ago is not a great big man, but he was riding with
00:35:53forward offset clip-ons.
00:35:57So they had got the message from the motorcycle, weight forward can
00:36:02help you.
00:36:04Ago could get the gas on sooner and probably harder than old Mike, but
00:36:12Mike had more horsepower.
00:36:14It was back and forth.
00:36:17Yeah, reminiscent of the Matt Maladon, Amar Bazzaz, and then who was
00:36:25his crew chief again?
00:36:26The Australian guy.
00:36:29Yep.
00:36:30Peter Doyle.
00:36:31Peter Doyle.
00:36:33They jammed Maladon way up on the front.
00:36:36They put a giant pad behind his ass on the motorcycle and shoved him
00:36:41forward and it worked out better for him.
00:36:43The stopwatch agreed.
00:36:45That was supposedly when he first rode the Suzuki, I think.
00:36:49And Doyle watched him go around and then wordlessly went and got the
00:36:56old black rubber and the duct tape and made him a butt stop that
00:37:03pushed him forward on the bike.
00:37:05And of course, when Honda built the 800cc bike that was ridden by
00:37:12Pedrosa and Nicky Hayden, a V engine can never be as far forward as
00:37:23an inline engine.
00:37:26So to compensate, they had the rider pushed far forward.
00:37:32The windscreen had to be cut down.
00:37:35This is the modern look, is the rider forward.
00:37:39And it was very obvious in that case in 2007.
00:37:46If you can't get the engine far enough forward, move the rider.
00:37:51And these are pragmatic things.
00:37:56You can get the two bathroom scales and learn a lot that way.
00:38:00Mike Baldwin did.
00:38:01He tried different positions on the motorcycle to see how much it changed
00:38:07the weight on the front.
00:38:08Because he was having trouble trying to accelerate, trying to steer,
00:38:14having the front wash out and have Dave Roper go zooming by, possibly
00:38:22raising one hand in silent salute.
00:38:25So Mike went home, got the scales, worked out how much extra weight he
00:38:31could put up front by adopting that
00:38:35McDoon forward stance.
00:38:39And he stopped washing out the front.
00:38:41Science.
00:38:43Yes, practiced at home.
00:38:45He had to get the bathroom scale from upstairs and the bathroom scale
00:38:50from downstairs and managed to get them to the motorcycle without being
00:38:55detected.
00:38:59That's pretty good.
00:39:01Well, I like to see people taking a direct approach.
00:39:05And that's the thing about motorcycle handling.
00:39:08A, it's tremendously individual because we all have a slightly different
00:39:13way of communicating with the motorcycle.
00:39:17And some people are going to be very sore after an hour on a bike with the
00:39:23clip-ons or the bars at an unfavorable angle.
00:39:29Where's my arthritis medicine?
00:39:33Making the motorcycle fit the rider in all ways is very important because
00:39:39unlike a car where you're just sitting in a chair and working the controls.
00:39:44People are all over the motorcycle.
00:39:48I realize there's a lot of most riding takes place like you're driving a car
00:39:53and that's just fine.
00:39:54We don't we don't want to have an alarming experience every minute.
00:39:58But well, I mean, but you know, in terms of testing, it's always for me if I
00:40:03go if I go out especially on a track only press launch for a real sporty
00:40:07bike.
00:40:08I will do laps.
00:40:12Particularly familiarizing with the track.
00:40:14That's when I do street pace laps and I do a not hanging off and I will I will
00:40:18pick a gear and I'll try to ride a swift pace, but I will also ride it without
00:40:23being that dynamic.
00:40:25I'm all over the bike kind of shifting load.
00:40:28That's one of the beauties of motorcycling is that as you described
00:40:31recently, you know, Freddie Spencer and Irv Canemoto trying all these different
00:40:36things during the test and Freddie going the same speed.
00:40:40It's just how much sweat he was making in his helmet as was the measure of how
00:40:45much work it was.
00:40:46And Mr.
00:40:47Oguma who was in charge of that Brazil test, which was probably 80 early 82.
00:40:56Mr.
00:40:56Oguma was kind of making these questioning faces and Irv went to him and
00:41:02said, can you say, do you understand compensation?
00:41:07Ah, I see.
00:41:09Yeah, genius, genius level compensation.
00:41:12Yes.
00:41:13Freddie had that wonderful ability to instantly adapt to things and part of
00:41:21that was his how he came into the world, what his package software was, pardon
00:41:28me, bundled software.
00:41:30Well, that Wayne Rainey was kind of like that too.
00:41:32Couldn't he just, they just show up at a test and wing the daylights out of
00:41:37just about anything.
00:41:38He just had the ability to say, or I mean, not perhaps, perhaps consciously,
00:41:44perhaps not consciously.
00:41:45We should ask him, but you know, just making it work.
00:41:49Yeah, regardless of what he's given to a point.
00:41:52Uh, I was at the, the, uh, Yamaha museum.
00:41:57They call it the communications Plaza.
00:42:00I think it has a lovely brick circle out front.
00:42:02It's very nicely landscaped and they're lovely things inside.
00:42:06And I had a conversation with a Japanese engineer who said, because, uh,
00:42:14Wayne Rainey could ride anything.
00:42:16We gave him, we lost our way because we wanted to find out what was better and
00:42:24what was worse, but he could go the same speed no matter what.
00:42:29So we thought, what should we do now?
00:42:34And I think that ability to, uh, to compensate is, is a marvelous thing
00:42:40because of course you, uh, get onto an unfamiliar machine and, or arrive at
00:42:46an unfamiliar track and three laps, you're under the lap record.
00:42:49Ha ha hot stuff.
00:42:52But, but, uh, as far as those are not the qualities you want for a development
00:42:58rider, you want the conversation.
00:43:01Yeah.
00:43:01And I think, um, it's reminding me also who else, but Wayne Rainey won world
00:43:07championships on in 500 on Dunlops.
00:43:13I think I don't, there may have been somebody else, but it wasn't common.
00:43:18I don't think so.
00:43:20Again, working with something that other people were not readily adapting to.
00:43:28So.
00:43:31Um, rake trail wheelbase, you know, those are our basic numbers that
00:43:36we pay a lot of attention to.
00:43:37I find rake and trail important to me when I'm testing motorcycles.
00:43:44Uh, same with wheelbase.
00:43:47I want to say I've been very happy over a long period of time with things in
00:43:52the 24 degree range, about four inches of trail and a 55 to 57 for something
00:43:59that's at least moderately sporty.
00:44:03That those numbers do work really well, but it also see them a lot.
00:44:07You see them a lot.
00:44:09And that is the kind of the happy envelope.
00:44:13You have people like Eric Buell doing everything possible to get so much
00:44:18weight on the front, to have the rigidity of the chassis, to be able to
00:44:21do a 21.6 or whatever that was on the XP nine with a 3.3 inch trail.
00:44:28And they work pretty darn good.
00:44:29They were, they were agile, quick turning motorcycles, even with a big lump of
00:44:35motor inside of them, a sportster motor, you know, they did remarkable work.
00:44:40It is a heavy engine.
00:44:42The flywheel is heavy.
00:44:43Uh, but again, it was concentrated and also we're putting the exhaust system
00:44:48under the engine to keep it off the back to, you know, so there was something
00:44:53there, uh, I think now to alternative motorcycles, alternative riding position.
00:45:00There was a Kneeler, the Norton Kneeler.
00:45:02There is of course, Dan Gurney's famous alligator.
00:45:06And in riding the alligator, there's a lot to be said for it.
00:45:09They were really remarkably confidence inspiring to ride and you could go
00:45:15really fast, but the, by necessity, the wheelbase was relatively long.
00:45:20Um, Dan was long and you're, you know, um, the ones I rode were always the,
00:45:28the, uh, Honda 650 that was breathed upon by all American racers.
00:45:34And I have never ridden a single that is so much power, so much response.
00:45:40They were bored out to about where they were in displacement
00:45:43was increased to about 700 CC.
00:45:46The intake port angle was changed.
00:45:48So they would weld the head and they would make it a downdraft rather
00:45:51than the very traditional dirt bike, horizontal intake, 90 degree into
00:45:56the combustion chamber, anyway, ran spectacularly strong and really fun to
00:46:02ride the roll response because the motorcycle was so SWAT.
00:46:06The roll response was exceptional.
00:46:08You could really roll it over, but you had a very long arc.
00:46:12You know, it wasn't quick steering in the sense of a 54 inch wheelbase
00:46:17motorcycle that goes and just hooks around the corner, really interesting
00:46:20dynamics and different, but they're not using that in MotoGP.
00:46:25I learned a great deal from Hurley Wilbert who built motorcycles and
00:46:32he rode them in competition and he actually thought about them.
00:46:38One day he had an opportunity to test the special frame bike that he had
00:46:46built against Randy Hall, who also worked for Kawasaki at the time.
00:46:52Randy's bike had the engine much higher in the chassis and at the
00:47:00time that dark cloud from England labeled low center of gravity as
00:47:08the key to handling was still throwing its shadow and Hurley was
00:47:18surely mortified that he could go faster on the bike with the engine
00:47:25set higher in the frame.
00:47:30And we had a big phone call about this and he said, here's what I think
00:47:34is happening.
00:47:35He said, I'm accelerating off the corner and that high engine increases
00:47:44the weight transfer to the rear wheel so I can throttle up quicker because
00:47:50I've got more load on the tire.
00:47:52It can transmit more torque.
00:47:54So ideally we want the engine high enough so we can get that rapid
00:47:59transfer.
00:48:00Now in 1972 Kawasaki had laid on a bunch of testing at the old Ontario
00:48:08Motor Speedway, which is now housing development, I think.
00:48:11In an empty mall.
00:48:13Okay.
00:48:16And 1972 was the trailing end of the long swing arm era.
00:48:23Oh, you've got handling problems?
00:48:24Put on a longer swing arm.
00:48:28What was happening to Ivan de Hamel, their star rider, was that as he
00:48:33gassed it off the turns, instead of accelerating, it spun and the back
00:48:39end slid out.
00:48:41Not enough weight on the rear wheel.
00:48:43So they put in a shorter swing arm and he began to go quicker.
00:48:51And in general, this is what is found, is that you can put the engine
00:48:58too low.
00:48:58You can make the chassis too long.
00:49:01Either way, you're not going to get the weight transfer that will load
00:49:06the rear tire so that you can put a lot of torque to it and accelerate.
00:49:12And I'm sure that dirt trackers have had this as a rule for many decades
00:49:19is, if it won't hook up, shorten it up.
00:49:24Because then you can transfer weight onto the back more quickly and more
00:49:28of it and get off the corner.
00:49:31Because if you don't get off the corner, you're not getting anything
00:49:34else.
00:49:36Doesn't matter how much power you've got.
00:49:38That's shortening the wheelbase.
00:49:42That's shortening the wheelbase.
00:49:44It's not shortening.
00:49:45I mean, it is shortening the swing arm.
00:49:47But as the trend has been, we've been looking for a longer swing arm
00:49:52within the confines of the 54-inch wheelbase.
00:49:55So the position of the wheel is there to take the weight transfer, but
00:50:02it's giving less of an arc through its compression.
00:50:06Now, it used to be that when you opened up a Japanese engine crankcase,
00:50:10you would see the crankshaft, the two gearbox shafts, and the kickstart
00:50:14axle all laid out there.
00:50:17All in a row.
00:50:18Yes.
00:50:18Like a beautiful little tray.
00:50:20Easy to work with.
00:50:21Just stick the parts in one after the other.
00:50:24Yes.
00:50:25And a lot of bikes had 19-inch swing arms because this way of laying out
00:50:31the parts was long.
00:50:33And the swing arm pivot has to be behind that.
00:50:37And it turns out that Moto Guzzi, with their first, their earliest
00:50:44horizontal singles, they looked at the thing and they said, this engine
00:50:48is really long because the cylinder is lying down flat.
00:50:52Why don't we take the two gearbox shafts and put them one on top of
00:50:57the other, shortening the engine by one shaft width?
00:51:03Well, by the width of the gears on it.
00:51:06So that is a vertically stacked gearbox.
00:51:09Yamaha applied it to their two-stroke 500 GP bike in 1984.
00:51:16And since that time, one company after another has adopted vertically
00:51:20stacked gearboxes to make engines more compact.
00:51:24Yeah, they made a huge deal out of it with the original R1, the 1998
00:51:29YZF-R1, vertically stacked.
00:51:32And you'd see the shift shaft going, you know, way up.
00:51:36Yeah.
00:51:38Yep.
00:51:38There was a lot with that bike.
00:51:41It was exciting to ride.
00:51:43It had a relatively short raking trail.
00:51:46It was very 250-like for a leader bike.
00:51:49It was certainly 600-like.
00:51:51It had the long swing arm.
00:51:53You know, I think they were touting it to be 22-plus inches, but within
00:51:59a 54-something wheelbase.
00:52:02And that's also the bike that had the famed negative travel on the
00:52:06fork, negative travel.
00:52:09That was in the press materials.
00:52:10And negative travel was extension.
00:52:11So it had, let's say instead of 120 millimeters of fork travel, it had
00:52:17140, but that extra 20 was built-in extension because it was so powerful
00:52:24and it was coming off of corners that it would let the wheel stay in
00:52:28contact with the ground just a little bit more often.
00:52:32Yeah, possibly giving you time to modulate your approach.
00:52:38It was very much a motorcycle that it really brought the low-power
00:52:47wheelie into constant existence.
00:52:50No bike before it had ever really done what the R1 was doing at that
00:52:54time.
00:52:55We were testing at Buttonwillow and we were running counterclockwise
00:53:01and you'd go by the pits and you do a right and you accelerate hard
00:53:04up the straightaway into these S's that then went into a left.
00:53:08And it was, you come out of that corner and you do steering input
00:53:12that for the first S and you'd realize that the wheel was, you know,
00:53:16some, you know, inch or two inches off the ground.
00:53:18It was, you had to start to plan ahead.
00:53:21Yeah, I remember that one of the match races in 76, Steve Baker was
00:53:30coming off corners with the front wheel up and the bars at whatever
00:53:36angle that, you know, like motocrossers steer in the air by using
00:53:41the throttle for pitch and the turning the bars for roll.
00:53:46And he was doing that then and people were.
00:53:50It was just because the the TZ750 Yamaha was a power-laden monster
00:53:57of its time.
00:53:59Now everyone can have monsters that are even more powerful, should
00:54:05they so desire.
00:54:09So what do we know about frame geometry in MotoGP?
00:54:12Do we have any numbers?
00:54:15No, I just, I sort of lost my connection there when it was, they
00:54:24were giving them 23 plus or minus.
00:54:29And it's typical for MotoGP bike of a certain era to have a steering
00:54:36head that's made like a like a big pot.
00:54:39And so you could move the whole steering axis forward or back, but
00:54:45now they want to bring the engine air in through a central intake
00:54:51that sometimes all that there is of the steering stem is a is a sort
00:54:58of a wing section in the middle of the air that's going to the intake
00:55:02air box.
00:55:03So I don't know what they're doing there.
00:55:06I can't imagine that it's greatly different from from what we're
00:55:11accustomed to.
00:55:12But I want to mention one of the things that's so important to light
00:55:18handling and that is light wheels and brakes.
00:55:22Because if you imagine sitting on a motorcycle in empty space with
00:55:30the front wheel turning at a hundred miles an hour and you take hold
00:55:34of the bars, it's going to resist you, your efforts to tilt it out of
00:55:38to rotate it out of its plane because of the gyro precession force.
00:55:44And the heavier the wheel, the greater the resistance and the resistance
00:55:51increases as the square of the speed.
00:55:54So motorcycle of the style and vintage of a CB900F has very heavy wheels.
00:56:08They're large, they're heavy.
00:56:10When they went racing with those things, they put a 16-inch front on
00:56:14them.
00:56:14And if you compare that with the weight of a modern sport bike front
00:56:22wheel, it's like so different.
00:56:25And then you've got a brake disc on either side that weighs five pounds
00:56:31on a production bike.
00:56:33You go over to a MotoGP bike, it has carbon discs.
00:56:38The carbon is lighter still.
00:56:41It weighs between one and one and a half kilograms per disc, which is
00:56:47that number times 2.2.
00:56:50Magnesium wheels or carbon fiber wheels have been the single greatest
00:56:56change I've ever felt between two versions of the same bike.
00:57:00I rode a GSX-R750 that was heavily carbonized, so to speak.
00:57:06And it was remarkable.
00:57:11It was incredibly light.
00:57:12Overall, it was something in the order of 350 pounds, maybe.
00:57:19Very light motorcycle, had carbon fiber wheels, and man, what a
00:57:26remarkable thing that was to ride.
00:57:28It was just so responsive and so easy to turn.
00:57:32And of course, when you're decelerating light wheels, you're decelerating
00:57:38them linearly and also as a flywheel, the rotational deceleration.
00:57:43And so if you have a heavy 18-inch wheel, your braking distance,
00:57:48everything gets worse.
00:57:50It's one of the frustrating things that I've found with Harley and
00:57:54basically cruiser manufacturers, but particularly the large-volume guy,
00:57:58Harley, is that weight hadn't really been a discussion for them 15 years
00:58:05ago, and it is now.
00:58:07They're having the discussion about weight.
00:58:12You're using lighter wheels, like the CBOs that were launched in
00:58:1623. Lighter wheels, they've put the inverted fork on the touring bikes,
00:58:22and they've stiffened that front end up.
00:58:23And so you get a similar geometry, but the response, the steering response
00:58:29feels quicker because of what you were discussing earlier about the flex
00:58:33between the ends of the handlebar and the axle and ultimately the contact
00:58:38patch. So you're sending, you're telegraphing the message you want to
00:58:42turn, and it's being lost in a bit of flex, whereas with a stiff fork,
00:58:47it isn't lost, and it feels like quicker steering.
00:58:50It's not delayed. It happens now, yeah.
00:58:51And it feels like quicker steering.
00:58:53We found that with dirt bike testing.
00:58:55When you were talking about the force required to change direction at
00:59:01high speed, there's multiple stories in the lore of Freddie Spencer
00:59:06bending handlebars on his Honda Superbike back in the day because he
00:59:11was trying to, you know, he's bending his one-eighth or seven-eighths
00:59:14Superbike bend handlebar.
00:59:16I believe you mentioned Ben Spees had bent clip-ons on something he was
00:59:21racing. I don't remember what.
00:59:22Yeah, at Motegi. It was a, oh, what was it? Ducati. Anyway.
00:59:29But Ben's a burly guy, like Ben was a bigger guy.
00:59:33That was one of his disadvantages in MotoGP because he's racing against
00:59:37a bunch of jockeys.
00:59:37Motorcycle-sized men.
00:59:41Yeah.
00:59:43Well, we can't all get into the ball turret on a B-17.
00:59:51Yep, there's certain jobs I won't get. Jockey is one of them.
00:59:56Yeah, well, or what Steve Johnson, the drag racer.
01:00:02He hasn't had a decent meal in 25 years.
01:00:07Because he's a normal, a man of normal height and there's just, you know,
01:00:11if he stands sideways, he disappears.
01:00:15Because he's doing that to be as light as the, as the women in the class.
01:00:22That's one of the great attractions is not only can they do the job.
01:00:25They can see the tree coming and they know when to do it.
01:00:30But they aren't carrying a lot of extra mass to make the engine say to
01:00:36itself.
01:00:36This is a lot of work.
01:00:38I, I'm not up to it.
01:00:40Yeah, Ben.
01:00:42I believe Ben had a very, very vigorous D-mass program going on.
01:00:47He was trying to lose, you know, upper body mass.
01:00:53I recommend the marine for my, my, my middle son.
01:00:58Went to the gym and made himself into a
01:01:03Paragon of, of gym product and it's in the Marine Corps.
01:01:09He lost a lot of muscle mass because what they wanted was the classic, the
01:01:14guy who can run a mile, swim a river and climb a tree.
01:01:19And that's a light, wiry person.
01:01:23So handling, we, we want to re-emphasize that it is personal.
01:01:33Handling is not a, a platonic ideal that is floating somewhere beyond our
01:01:42Ken.
01:01:43It is up to the person to get the response that he or she
01:01:49Needs.
01:01:50It's not a matter of style.
01:01:52It's a matter of how it works, how it works for you.
01:01:55So I've talked to people who said to me, I like to ride a really heavy
01:02:01motorcycle because it makes me feel safe.
01:02:04Well, you can't argue with that.
01:02:06That's a feeling.
01:02:07Emotions.
01:02:08We do not apologize for
01:02:11That individual.
01:02:12Absolutely true.
01:02:13Absolutely true.
01:02:15However, however, emotions will not get you a lap time.
01:02:20No, they sure won't.
01:02:21And so that's the thing.
01:02:22It's is, is it, it is very personal.
01:02:24It's like, I like the response of this fork.
01:02:27I like the way this heavy bike steers or I like the way this cruiser feels.
01:02:31Harley Davidson has or had a spec for inside bar pressure while turning
01:02:37their motorcycle.
01:02:39So they had, he wouldn't tell me what it was.
01:02:41I was talking to one of the chassis development guys and because we've
01:02:45always praised neutral handling in, in the magazine and neutral handling
01:02:48means I'm going into a corner and I'm trail braking.
01:02:51The bike doesn't want to stand up.
01:02:53If I release the brake while I'm turning in trail braking, I'm breaking
01:02:57down to the apex.
01:02:58I'm combining turning and stopping and I release the brake.
01:03:01The bike does not fall into the corner either.
01:03:04Neutrality is the bike goes around the corner mostly regardless of how
01:03:09you're doing chassis or brake inputs.
01:03:13That's neutrality.
01:03:15We have always praised that Harley Davidson says.
01:03:18No, we want a few pounds.
01:03:21I'm guessing because that's what it feels like.
01:03:23We want a few pounds of inside bar pressure and that when I want the bike
01:03:27to stand up exiting the corner, I'm relieving that pressure.
01:03:30I'm not standing the bike up.
01:03:32I'm pushing it down in the corner and I'm releasing and coming up and
01:03:35that's what they go for, but that isn't necessarily what you're looking
01:03:39for on Ducati in MotoGP.
01:03:43So, but yes, there is a vast array of personal taste.
01:03:48If you talk to Matt Maladon, I don't like to run a lot of fork oil because
01:03:53it gets in the way of the feel of what's happening at the contact patch.
01:03:56He said that.
01:03:57Yeah.
01:03:57And, and a racer.
01:03:59Compressing air.
01:03:59It's compressing air and getting very stiff.
01:04:02He's like, I just want a little sprinkling of oil in there and then
01:04:05the rest is up to me and you can't argue with that, right?
01:04:10You know, I'm not going to take the oil out of my fork, but I'm also
01:04:14never going to lap anywhere near what Matt Maladon was lapping.
01:04:17So there is a tremendous amount of personal taste, but there is also
01:04:20a box of what you were saying, a development rider is searching for
01:04:25a truth and a path that's improving the overall direction of what
01:04:30the chassis is capable of doing.
01:04:33Yep.
01:04:33There is a truth there.
01:04:35We should make the point that a lot of handling depends upon machine
01:04:40condition because when I was AMA tech inspector for a brief period,
01:04:49I had two motorcycles come across my table that had no swing arm bushings.
01:04:55I found loose front ends so that if you held the brake on and push forward,
01:05:01it went kathunk because the bearings were loose.
01:05:05The steering head bearings were loose.
01:05:06The rider was riding it like this.
01:05:08And all sorts of other things.
01:05:12So it's a good idea to periodically check your tire pressure because the
01:05:17tire is an element that can produce steering delay.
01:05:21It can also overheat when it's run too fast, run fast because the lower
01:05:28the pressure, the more the rubber flexes, the more heat it generates.
01:05:32It's desirable to periodically kneel at the side of the machine by one of
01:05:40the wheels, take hold of the top of the wheel and try to rattle it back and
01:05:45forth.
01:05:46If there's anything loose, wheel bearings, swing arm, pivot, axle, etc.
01:05:51You will feel a click.
01:05:54You'll feel some lost motion front and rear.
01:05:57Try that on your Norton Commando with isolastics and shims or the veneer
01:06:02adjustment.
01:06:03We could do a separate podcast on isolastics.
01:06:06So vintage bikes, typically vintage bikes had roller bearings in the
01:06:13steering head.
01:06:13So most of the time you can replace those with tapered rollers.
01:06:18Balls versus rollers.
01:06:22And if you get tapered rollers, cone versus cone, and then you tighten those
01:06:26down, you get a much more positive feeling through the steering head that
01:06:30just feels more rigid and communicative, robust swing arm bushings.
01:06:35And this is all experience I have from RD350 and XS650 because those
01:06:40chassis, the swing arms will interchange on an XS and RD350, I believe.
01:06:45They'll just bolt right in.
01:06:46You switch from the plastic bushings to the brass bushings on the swing arm
01:06:50and you change to tapered bearings in the steering head and the bike, the
01:06:56motorcycle is transformed.
01:06:57The RD was transformed.
01:06:58Also put some decent shocks on it.
01:07:00But that would go, but good quality bearings, clean, properly adjusted swing
01:07:06arm linkage.
01:07:08You know, if you have a rising rate linkage, you know, it's not sealed for
01:07:13life, it's sealed for death.
01:07:14Take it apart, clean it.
01:07:17On my dirt bike, it's a regular, that's a regular service is lubricating all
01:07:21that stuff so that you have that beautiful compliance available to you.
01:07:25And there's no sticking friction to get in the way.
01:07:29If you're willing to do the work, you can learn a lot by moving your
01:07:33suspension through its full arc without a spring.
01:07:36Yes, there was a team in one of the junior classes in Europe that was
01:07:43having trouble with their bike.
01:07:46They took it here.
01:07:48They took it there.
01:07:48No one could help them.
01:07:50Finally, they took it to George Vukmanovich, AKA Little George, and he
01:07:58took the rear spring off and moved the thing through the whole cycle and
01:08:04there was a tight place.
01:08:08Let's fix that and test again.
01:08:11And the bike was cured because the spring is so powerful.
01:08:16You can't cycle that or bouncing on it.
01:08:19You're not going to get full stroke.
01:08:22I've learned a lot about front forks by cycling, stroking them with the
01:08:27spring with the caps off so that I can find a tight place if there is one.
01:08:34And on the other hand, could be its warranty.
01:08:41Don't want to do the work.
01:08:42Suspect you can't do it.
01:08:44Okay.
01:08:45Our official policy here at CycleWorld is we would like our readers to lay
01:08:55hands on their equipment and learn about it.
01:08:58Absolutely.
01:09:00If you don't want to, there's nothing we can do about that and good luck.
01:09:05Find a good technician.
01:09:07Get a good relationship with a good technician.
01:09:09Yes.
01:09:10The last thing I will say is check your damn wheel bearings, folks.
01:09:13Don't take it for granted.
01:09:14Take your wheel off and stick your finger in there and rotate that wheel
01:09:18bearing and if you feel any click, click, click, get rid of them.
01:09:22Start fresh.
01:09:23Yes.
01:09:24Thanks.
01:09:25Thanks for listening, everybody.
01:09:26That was What is Handling?
01:09:28Do we know yet?
01:09:29I don't know.
01:09:30It's always great.
01:09:34We are still enjoying this.
01:09:37It's always great to have these discussions.
01:09:39As I've said before, these were discussions Kevin and I would have on a
01:09:44fairly regular basis anyway, just as we discussed what shall we write about
01:09:48next or what's going on and we decided to make them into the show and we're
01:09:53glad we did because it's formalized it.
01:09:55We make a list.
01:09:56Kevin makes lots of notes.
01:09:58I make notes upon the notes and we take it from there.
01:10:02Hopefully, we're contributing to the signal in this great noisy world.
01:10:07So, improving the signal-to-noise ratio just a little bit.
01:10:12Thank you for listening and we'll catch you next time.