Rear Suspension Designs That Failed, and, of course, More!

Hello everyone and welcome back to the Cycle World podcast. I'm Mark Hoyer. I'm with Kevin

Cameron. If you've never joined us, thanks for joining us. If you have joined us, like I said,

welcome back. So we recently did a podcast about rear suspension, principally the swing arm.

Had a few little chit-chats in there, but we're going to talk about failures of rear suspension,

and things that we possibly pondered and looked at the sky and thought, what if the wheelbase

never changed? What if constant steering geometry? Imagine perfection.

Imagine perfection and then imagine getting into the dyno cell and putting a connecting rod in the

roof, for example. But yeah, we're going to talk about suspension, the failures of different types

of rear suspensions and all the implications of what we're working on motorcycles here.

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you're paying YouTube a lot more than you're paying us. Oh, no, did I say that? Anyway,

thanks for joining us. Let's get right into rear suspension, Kevin. Okay.

Front suspension came first because if you hit a bump and it's tall enough, it acts as it tries to

wrestle the steering out of your hands. Well, I think there's more natural padding on the other end

too compared to your hands. Well, that's true. Yes, that's true. Except for my

maternal grandmother. But front end needed suspension because otherwise bad things happen

right away. So people learned to ride with front suspension only, so-called rigid frame.

But there were efforts made to add suspension to the rear, most notably Indian in 1912,

who made an effort in that direction, was an option, wasn't a popular one. And

there were a number of attempted swing arm revolutions which failed because, well, I should

say giving rise to the wisdom of the ages, which was nothing steers like a rigid. Now,

the rider, a monopoly of control. You turn the bars,

causes the machine to flop over right or left at your choice. So, but if you have a swing arm

bike with a weak swing arm, then there's a second opinion on steering. Is the throttle

pulling, causing the chain to pull strongly on the swing arm? Are you hitting bumps? Is the frame

flexing? So, what was the good compromise in that period from the creation to 1935 was the

section tire. That was rear suspension, in effect. The same revolution had occurred in

automobile tires. They had learned the comfort producing qualities of not blowing the tires up

to 100 psi. And they began to build thinner walled, larger section tires operating at lower inflation

pressure. I'm a big fan of bringing back the more sidewall. We need tall tires, none of this

30 series, 20, 40 series, low profile, oh man, sidewall. That's where it's at.

Yeah, well, near the end of Goodyear's participation in road racing in 1984,

and right at the end of the two stroke era, there was created, and Dunlop did it too,

tall sidewall tires, because it was believed that if you added some lateral flexibility,

that the motorcycle would be more stable. There would be an opportunity for the flexing rubber

to provide damping force. But that diverts us from our subject, which is rear suspension.

Then came 1935, and two big things happened. One, Phil Vincent in 1929 had bought the name

and a few bags of frame lugs from Howard Davies, who had made his own motorcycle and won the TT on

it. He won the TT on a bike he'd built himself. So Phil Vincent buys it. Phil Vincent as a school

boy was drawing pictures of motorcycle frames. And what he built was a rear suspension that was

triangulated, so that the two beams of the suspension were more resistant to this motion,

which would cause the rear tire to tilt from side to side.

One of those bikes finished seventh in the 1935 TT. And remember, Vincent was never really a factory.

It was more like two creative guys with a lot of helpers.

And the other creative guy, of course, was still Irving. So here's this bike in seventh,

with nothing but factory Norton's and a couple of factory NSUs, which were just German Norton's,

some would say, ahead of it. Distinguished finish. Well, aside from the first place, which was Stanley

Woods on the factory 120-degree V-Twin Moto Guzzi with a triangulated swing arm.

And this was a shock because nothing steers like a rigid. People don't like to find that,

you know, they'll shout not killed. Well, actually, it's okay if the right people tell you to, you

know what I mean? People like to nail down these home truths. So no less an authority on everything

motorcycle-wise than Joe Craig, Norton's long-serving racing manager. In a 1942 magazine article,

he proclaimed that Stanley Woods could not have achieved his stunning last lap in the 1935 TT

on a rigid frame. Suddenly, everybody's got to have rear suspension. Rear suspension is hot. It

won the TT. Well, how can we do this on the cheap? How can we, you know, like make it look like rear

suspension or something like that? And this gave birth to things like sliding pillar. Here comes the

two members, triangulated members of the rear suspension, the hardtail, down to the axle holders.

And instead of just putting the wheel into the axle holders, you make room, weld on some brackets

and put the sliding pillars there and attach the rear axle to them. Presto suspension, not much of it.

It's there. And I got to say my experience with those types of frames is, you know, it's

possibly more comfortable, but perhaps also more unsettling.

Yeah. Well, of course, one of the things is I noticed that that detective dramas on television tend to be

better put together because so many people are working on them. And then along comes a family

comedy and it's, I think I'll go get a sandwich. So the fact that large numbers of people were

working on these concepts eventually made them, made them workable. There was a thing in 1919

called Coulson B. Coulson B, instead of attaching stick, slip, prone sliding pillars, had little

dinky vestigial swing arms at the ends of the hardtail. And the axle, I think, was supposed to

somehow prevent this whole thing from flopping to side to side. Footnote to history, Coulson B.

It went nowhere. So

this was pretty much the state of affairs from 1935 onward, although Vellisette enthusiastically

adopted rear suspension in the form of three pieces of pipe, not welded together, but mechanically

fastened, make those joints good and tight, and you might have less of this.

Never having ridden a Vellisette, I will have to defer to Mark who has not only ridden them, but

to an extreme. While the ridgents were, I had a 37 KSS with a girder fork and it was a pleasure to

ride on a winding road. And you can see, it was, for me, it was the education that took me from,

I'd already owned the KSS, or the MSS, which is the Pushrod 500 single. It was the first

swinging arm 500. I had the 19th bike off the line, in fact, for swinging arm bikes. And

it's a pretty good handling bike of the early 50s, mid 50s, British bikes that I've ridden,

much better than a sprung hub that Triumph was doing. We'll get to that. And that's quite a

contraption. But Vellisette swinging arm was pretty good. And as Kevin was talking about earlier,

getting some of the action, not rigidly connecting the steering head to the axle,

nothing steers like a rigid, they're connected. And that means they're not having a twist,

which Kevin's talking about, introducing rear steering, whether you're braking hard or accelerating

or hitting bumps in the corner and starting to get cycles going, where you just, I rode a Norton

500 twin that was a Model 7. And it was exciting. It was, it was not bad, but I mean, the Vellisette

for the Euro works pretty well, although getting back to it, the single, it had a vestigial seat

post in the middle of the frame, which is what came up between the gearbox and the engine.

And there's a lug for the swing arm pivot, which is a pipe through a lug that's about this wide.

And then you clamp on the swing arm arms, they have little pinch clamps on them. So you have to

pinch them, get them lined up, you know, so that they're not out of a skew. So there's some setup

there and then you clamp them on and it can't have any play in it. And I've, you know, it's,

sometimes you got to sleeve them and then you clamp the thing. I don't know. There's like a kit

Norton's having. Participatory motorcycling. Yeah, you got to really work at it. I mean, that's,

that's why we're here. And you know, there's plenty of stuff you can buy. You never think

about the swing arm pivot for the life of the motorcycle. In any case, they worked okay.

Bellasets worked pretty, the swing arm Bellasets worked pretty darn good. It was a step and it was,

it took some courage, I'm sure. Well, I want to give also one more little bit of credit to

Bellaset was that you could adjust the position of the upper shock mount. They had an arc in the

frame. We'll throw up an image. That famous arc, yes. And what you can do is basically

change how compliant the suspension is by tipping them forward or making them more vertical. And

it would change that physical ratio. And it's, it's useful. I mean, look at the size of me.

It improves the bike. And it was a method of adjustment that no one else had at the time.

Around 1950, Edward Turner did something very characteristic of Edward Turner.

He was the man who, when he designed a parallel twin four triumph, made sure that it would slip

into the frames that were made for the single. Now, this is not lavish manufacturing backed

by the courage of an enormous market. This is mind the pennies and the pounds will take care of

themselves. So what did he do? He designed the rear suspension into the wheel hub

so that it could simply be slipped into the axle carriers of the stock frame,

no modifications, no extra costs. Now, this has been, the spring hub has been referred to as a

jack in the, jack in the box, because if it happens accidentally to open something will spring out,

namely the springs. Well, I was very much told by my friend, the Bill Getty, who's run JRC

Engineering. He's an incredible British bike mechanic and his historical knowledge. He's

worked on everything. He used to run a shop for a long time and now it's aftermarket parts for

British motorcycles. But he said, you know, Mark, if you ever own a spring hub, try not to open it.

As Kevin points out, there can be explosive. The other big development in 1950 was, of course,

the Norton featherbed frame, which was

developed by Rex and Chromie McCandless in Northern Ireland as a result of actual testing.

And rather than armchair platonic theorizing such as we want a constant wheelbase, we must have

constant steering head angle. We must have purity in all things and perfection.

So Norton were so impressed with this thing, they contracted with the McCandless's to build the

frames for the 1950 TT bikes for Norton, the factory Norton's. And they won the TT. And not only that,

they gave the Italian four cylinder bikes a terrible scare because they could get on the gas

earlier in a corner. They were stable. They braked well. And in Norton's testing,

the featherbed version could be written around the outside of their previous bike, the so-called

garden gate frame, which was a single plane frame, similar to that of a bicycle.

The featherbed bed frame had twin loops, and the swing arm was placed between them at the

aft end so that it had a broad base for stiff mounting, not a lot of flopping and flexing.

And Jeff Duke would have won the World Championship on that bike first time out, except for tire

failures, chunking at high speed. So, and then in 1951, he did win the World Championship,

the last one that Norton would win in 500 or other classes. The singles were not finished,

but almost. However, the terror felt by the Italians resulted in a widespread

Nortonizing campaign. What is it about this bike that makes it so able? We'd like to have some of

that. And of course, the great ambition of English riders was to be summoned to Italy and be well

paid to arrive and to ride the frightening force. And they would bring with them, in their suitcases,

British made telescopic coilover rear suspension dampers inspired by those made by hand by the

McCandless Brothers, which included remote reservoirs, not to be seen again for 20 odd years.

So, this was a movement of goalposts. This set the scene for 20 years of convention,

in which if you wanted a good handling motorcycle, you would buy one of these Nortons with the

featherbed chassis, and you would try to understand it. And of course, it wasn't so mysterious.

McCandless moved the rider and the engine forward almost three inches. Big change. And

I've spoken to you before about the JSME article in which they ran

motorcycles stationary on a moving belt highway. And they tested them for stability,

and they found out that loading the front tire rather than the European practice of backing

the engine up against the rear tire produced stability and steering that did what you expected.

So, this was the new standard. And it would rule the world until the coming of Antonio Cobas and his

inventions in the early 1980s, which culminated in the twin aluminum beam

establishment of the present moment. Not to overlook the significance of so-called

trellis frames as practiced by Ducati. KTM also was an adherent of multi-tube space frames.

So, one of the very important things that Norton added was supple, smooth acting,

hydraulic dampers front and rear, telescopic fork in the front, twin shocks in the rear.

No more stick slip from scissors type dry friction dampers, which had been the world standard since

there was rear suspension. Sort of like a clutch. And before that it was used on on girder forks.

Yeah, you sort of sort of like a clutch, except it had two arms on it that were attached to

different elements. And that was your, you know, attached to the front wheel, attached to a fixed

area. And in some of them there was a big wing nut by which you had adjustable damping.

Steering dampers were like that for a time. You had a big knob. You could turn on your steering

head and the rod went through to it. Right into the 60s. Yep, to essentially the same

friction pack underneath the steering pivot, so.

Well, in 1973, there was an explosion of rear suspension innovation from Motocross.

And this is where suspension is so badly needed, so it's not a surprise that innovation

should come, should well up out of the dirt, so to speak. And

what had been the norm for many years was the three to three and a half inches of travel

of a pair of trusty old black curling shocks with a variety of springs that you could get

at your nearby stockists. And stockists. I've always liked that. I'm not going to say it again,

don't worry. Riders rode as hard as they could with those short travel units.

When they began to extend the travel, they found they could go much faster. Now, one reason is

that the energy absorption ability of a suspension is proportional to travel

squared. Double the travel, you can absorb four times the energy of the shorter travel unit.

And the other thing was that, as pointed out by former American Honda Racing Manager,

Gary Mathers, riders push as hard as they can, but they are stopped by what they call harshness.

And whether that means that your brain is being jarred into foolishness,

or that your muscles are unable to go any further in the direction they're going,

or your peripheral circulation shuts down, I don't know what it is. I'm sure that

sports physiologists could tell you what harshness is. But what happened was that as they

extended travel, at first everyone enjoyed the softer suspension and the ability to

magically travel at great speed over rough terrain. But as usual, people rode to their limit,

the harshness limit. So Mathers noted, they ended up with the same spring rate with 12 inches of

travel that they had had with three and a half inches. And I find that fascinating.

Well, racers, the good racers, what do they do? They follow any tester. You ride the bike until

it does something wrong. You push it harder and harder until it does something wrong. That's

actually the job. Because most things are good. That's 70%, 80%. Most things are pretty darn good.

But it's when you started asking me more. Long travel hit road racing too. And

one rider told me that with his long travel Honda with suspension that had the latest in low

rigidity compression damping. Traditional compression damping was just a hole through

which oil was pumped by the moving piston in the damper. What a suspension damper does is it converts

bump energy into the velocity of oil rushing through a limited area, in this case a drilled hole.

And the resistance to that flow goes up as the square of the flow, which means at some level,

the resistance becomes essentially rigidity. And there's all kinds of wonderful stories about

riders throwing shocks into into lakes or abusing them in other ways. But what this led to was a

new type of compression valve that was progressive. And that whose resistance was more nearly

proportional to shock rod velocity than to the square. And so this made it possible for

the rider I'm talking about to hit the banking at what used to be turn five out of the Daytona

infield up onto the banking without timing it to coincide with an upshift. He could just ride

through there on the power with this innovation. So this is not engineers playing with pencils and

papers. This is let's try this. Be sure to wind your stopwatch. Okay, here we go. Oh, that's much

better. Let's talk to the rider and so on. This is how it actually goes. We are not sitting in

Plato's cave looking at mere shadows of reality. We're getting in there and messing with it. So

we get results this way. Now there are some exceptions. The atomic bomb worked perfectly

the first time. Although there have been some fizzles since then. Well, the atmosphere didn't

even catch on fire either. That was one. No, hydrogen and oxygen failed to rush into each

other's arms. But it was a sort of nagging itch until they actually saw the fireball through

their smoked goggles. So when long travel hit road racing and street bikes, of course what

people noticed was these bikes have powerful brakes and pavement has more grip than dirt.

Which means you brake and the bike noses over rather radically.

And for each inch that the front suspension compresses, you lose roughly one degree of

your steering head angle. Now this is there are people who say that this can be a terrifying

thing and then there are others who dismiss it. But I've not risen to those

heights in my own modest motorcycling. So people began to say let's put a stop to this

extreme attitude change. We don't want to go back to short travel. Let's put anti-dive

onto the front end. And hydraulic, mechanical, there was a wide variety of devices. You may

have seen the Kawasaki ones that had all these levers which used the effort of the brake caliper

to follow the brake disc to generate a force that lifted the front of the machine.

Now Udo Giedel has commented that it could brake nicely or on a rough surface it could stutter horribly.

Then in the end once again reality prevailed because it was found,

wait a minute, these guys over at Yamaha are out braking our guys and they don't have any

anti-dive on their bike. What do they know that we don't? Well what they knew was that when the

front of the bike sinks dramatically it takes the center of gravity down with it. And that makes

the lever, the height of the center of gravity over the pavement by which front brake torque

can lift the rear wheel into a stoppie makes the lever shorter so you can brake harder

and not lift the rear wheel. And so overnight anti-dive just disappeared went off the street

bikes it was all gone. So embarrassing. And this is how things go. There was initial resistance

to monoplanes. I mean where the bracing where well they're inside the wing so to speak.

But I don't really trust that. I mean the biplane is built like a box kite you know you can trust it.

They didn't like a canopy over the pilot because he couldn't feel the slide slip on his cheeks

and judge how the turning was going. Well I mean imagine a Cessna 195 in the late 40s with no

wing braces no it just it just was a straight wing sticking out and there was no nothing

visibly holding it.

Well anti-dive disappeared okay. There were various strange anomaly anomalous

suspension proposals from like 1970s onward. And US Kawasaki played with what they called the

Fubar rear suspension. There were two swing arms going up and down together. Their aft ends joined

by an upright that was perforated for the rear axle. When they described this to me it sounded like

someone slightly familiar with the A-arm geometry of race cars had fallen in love with the idea of

the virtual pivot that is far away in space and so what was hoped for initially from this design

was that it would absolutely prevent wheelies allowing you to just scoot out of corners and

disappear. But in practical sense I think they discovered anti-squat and they actually put this

on a van de Hamels race bikes air-cooled and liquid cooled from 73 to maybe 77.

And then it disappeared they it didn't go any further but they put a lot of effort into it.

Another possibility which I've never seen in the aluminum and steel is the

Chebyshev linkage. In 1859

Pavnuti Chebyshev a Russian mathematician was trying to devise a way to change straight line

motion into rotary motion and in the process he came up with twin swing arms that were crossed.

This was perfect for the constant wheelbase theorists because at last you could have the rear

axle going up and down in a straight line zero wheelbase change. Perfection is at hand.

I don't even know if any prototype of this kind was built but there was the idea.

So what a lot of these ideas for rear suspension were trying to do can be broken down into three

areas. One is people were beginning to be aware as engines grew more powerful remember the two

strokes came to Daytona with 100 horsepower in 1972 that got people thinking. Chain force had an

effect on rear suspension it might either cause it to rise up or to squat down. And so people were

trying to negate this force so that it would be neutral. Hossack's rear suspension he wanted the

swing arm center plane of the swing arm to be horizontal he wanted the chain above it to be

horizontal and parallel with the pavement. ATK came out with a similar idea they placed two

sprockets clamped one above the other to the chain side swing arm beam and they were arranged at

such a height that the upper chain run and the lower chain run when either of them was under

tension would be parallel with the swing arm. So there would not be this tangent force

tending to cause the swing arm to extend. The thing that I loved about ATK was that they

made a demonstration toy was fascinating to play with you could you could change the variables

so that was bad normal thing whether rear suspension extends or it would be super modern

with no net force no effect from the chain tension on rear swing arm height suspension height.

Then the the second idea was no rather than setting the swing arm free from chain pull

let's use the chain pull on these powerful motorcycles which otherwise will squat down

in the rear when they accelerate let's use it to generate the lift force just to the point

that it cancels the squat so that here you are in the turn trying to accelerate and as you twist

the throttle and the rear end squats down weight comes off the front tire and goes on to the rear

tire and the front tire pushes you head for the outside this is squat and push

and I remember seeing one of the South American lads who made it big in GP racing

come in to his crew and make the universal sign for push which is

millibars crossing yes yes and which is now called something else they call it

closing closing the front end and then the third possibility was to

completely ignore all of the above and focus only on constant chain slack because

there are some peculiar motorcycles out there Yamaha's TZ500 you had to be careful adjusting

the rear chain slack because there was a place in the arc of the rear suspension where it got real

tight that's where you had to adjust it and so these guys were going to to nail down constant

chain tension by making the swing arm pivot concentric with the output sprocket centerline

famous spawn in chassis's got that and then BMW was playing with that on their dirt bike which

didn't work out too well for them it didn't work out too well for anyone because it completely

ignores the chain pull effect on rear suspension height and but it's invented several times each

year and it probably will be as long as the motorcycle exists hey here's a good idea why

don't they do this but it's not a good idea it works it achieves its purpose but it ignores

effects that cannot be ignored on powerful motorcycles

so all these uh well then then there's Haasek Haasek was involved in formula one

development and at one point they had a chassis bolted to the wall and they had a

great big bar through the the projecting end and they were going to test that the twist resistance

in pounds per degree and this is good this is this is finding out stuff you want to know by

lashing up something that doesn't cost a million and a half dollars and has to come from a German

high precision outfit um bathroom scale and the drill press uh you got it test your spring

right so it's a famous picture of dam dirt dam drainage suspension springs you got it so um

um

I once uh stood just off of um what used to be turn nine at Laguna the left hairpin

and watched the tz 750's upshift off of that corner as soon as the clutch went home

clunk the bike rose up and hit the upstop they had plenty of anti-squat

this is why um in the early 90s adjustable swing arm pivots began to be seen

adjustable height usually in the form of a rectangular opening on either side of the frame

into which plugged a plate with a hole for the swing arm pivot at a particular height

and you had a fifth case of these like fine cigars and you could select the ones that had

the height change that you thought would put an end to all your problems and shut your rider up

with all his complaining whiners so uh that was

that was that when it came to foobar uh nothing is going to change the fact that the thrust

accelerating the motorcycle is at ground level whereas the center of mass is maybe 20 22 inches

above that what that means is the thrust is tending through this lever arm to exert a torque

on the chassis and lift the front wheel off so what you need to prevent this is either a chaperral

like um big suction fan up front that is pulling the front end down onto the pavement or winglets

or a tiny rocket motor that fires only when you accelerate nothing else is going to stop wheeling

no complexity of linkage gears cams and linkages forget that now here come the elf alternative

motorcycles at first andre de cortons a frenchman uh with formula one experience

reason very reasonably there must be with all the research done in formula one

concepts that are immediately applicable to the motorcycle that poor primitive creation

which will greatly improve it and i will be a star well one of their improvements was

everyone knows that a motorcycle handles better if it has a low center of gravity right wrong

look at modern motorcycles you will see that the rider is way up in the air above the rear tire

it used to be that the seat back the underside of it was arranged to be barely greater than the

suspension travel and many a motorcycle had tire burns on the underside of the seat pan

they found that that didn't work well well honda bought into elf because they wanted to be

in a position of advantage and this looked like it in 1984 they brought their

uh

nsr 500 their new four-cylinder bike two-day tona with the fuel carried under the engine

and with the exhaust pipes routed over the top protecting the rider by means of an insulated

dummy tank and it was found out they added they used this concept on their 500 gp bike

as their main they placed all their bets on this and freddy spencer said i can't

change direction as quickly on the bike with the fuel on the bottom as i can on my old three cylinder

and a test was arranged orange cones created a slalom the three cylinder was sent through

the slalom until freddy said that's about all i can do and clicked they had a measure

they sent the nsr 500 into the slalom at freddy's entry speed and knocked all the cones down

actual physical testing not just sitting by at fireside in a comfortable armchair reading

plateau actual testing revolutionary so that was the end of that it was also the

end of the courtesans they brought in two other fellows instead and this is an excellent story

because it shows persistence willingness to spend money

and ultimately acceptance of the fact that it added up to nothing

but that's something learned so what went on there was that the radical bike

didn't go as well as some bikes modified to be somewhat less radical and so they went in that

direction and all the hub center business with gears cams and linkages gave way to a simple

almost like i'm at first and strut and the poor guy on the bike is trying to give good feedback

and get good finishes and he was fifth or third or he had some good finished positions in the

championship in the middle 80s so it can't be it was ron haslam

very earnest a corner speed rider the bikes wheelbase kept getting longer and longer they

started at 53 inches and they ended up at 57 plus and when uh what was it scott redding i'm not

sure which rider it was told me about the difference the physical difference in the

motorcycle from a corner speed bike to a point and shoot bike he said the corner speed bike is

long and low and that's what honda built for ron haslam and of course as the bike became more

conventional people had heard of macpherson strut and a lot of people were driving cars with it

the extremists squeaked and moaned because it wasn't radical enough it was not true to the

original concept of changing everything wait a minute what are we trying to accomplish here

to annoy people or to win races so uh that just didn't work at one point

a quote on from a rider was directional stability a problem at almost any speed

that's for elf 2a for elf 2c uh front pattern of terrifying proportions but braking was

exceptionally good because you know that a telescopic fork side loaded by a braking force

operating on a long leverage tends to bind tends to cause addiction that prevents the

front end from following the pavement surface during hard braking but with a pivoted front end

no addiction excellent grip shortest braking distances and when harley built their

retro leading link suspension i went to interview the engineer who had done the project and he was

sort of apologetic and i said well i want you to tell me there's got to be some point of superiority

here and i want you to tell me about it well he said um it does have the shortest braking distance

of any bike we make and this is what you would expect from a pivoted front suspension so

there was a point of advantage but it wasn't enough to win races and honda pulled out of the

elf honda thing and no more was heard about it so tough one

so

then we have

leading link

bmw made long leading link earls forks for their flat twins in the early post-war years

and for a number of years during that period uh and the thing about leading link is that

instead of going up and back the way the wheel does with the telescopic fork it goes

nearly up and down with very little wheelbase change now how you can

stiffen this assembly of two little leading links it's kind of like koulson b so that the

wheel doesn't cock from side to side as you go through a turn with bumps in it i don't know

but kutzi managed to win the 350 world championship five times in a row 1953 through 57

and then they pulled out of racing and that was that bmw kind of like the emperor has no clothes

they finally realized marketing realized that the graceful waving of the front end on those

so that came to an end it's an historical footnote it was an era

was an attempt to find a better way to do it

so then there was the bmw tazy um early what 90 1990 i think it was shown the cologne

and it has a hub center front end on it if you're not familiar with a hub center imagine

a drum like open at the ends a ring that is spoked into a rim then imagine two large bearings

inside that empty drum with another drum pushed through it and the drum that's pushed through

it has a kingpin and grasping the bearings from one or both sides by reaching in through the

open ends of the drum is a front swinger now the only thing that steers is the wheel the disks

and the brake calipers there are no ponderous fork tubes swaying from side to side with the wheel

and this is potentially a strong point of this hub steering because it is more resistant to wobble

wobble is a rapid oscillation of the front wheel which generally times out at about 40 or 45 miles

an hour or if you put your hands back on the bars if you have uncertain motorcycles decided to

do the snaps on your gloves oh yes i won't do that again um life's little travails

so the the tasey i wanted to succeed because it looked right we all did and the frame the frame is

just a a thing that went from the frame was the engine it went from the front swing arm pivot

to the rear swing arm pivot there was no steering head up in the air with long poles going down

just little arms delicate little steering arms to get down there of course the the front swing

arm had to have elbows to provide clearance for the front tire and this was a problem for uh

ron haslam at one point on the number three elf honda bike because going through i think a left

hander um and he used a lot of lean angle he was a corner speed stylist he dragged the swing arm

on the pavement not many can make this claim so this stuff

came to an end uh tasey

i encountered a man who liked the tasey that he bought so much that he bought two more

so that he would have one at each of his three residences and he was a

cheerful guy who just loved his motorcycle so he had three of them the other neat they are cool

you know i don't know if i need three but they are it is a charming thing but uh the thing is

there are a lot of ways to build a motorcycle that will chuck along the highway

and get you where you're going and provide you with a sporty feeling but

with that i'm sure for example that we could build a lovely chassis of adequate stiffness

out of steamed plywood but when you push something to its limits you learn other things and racing

riders on racers on tasey or similar bikes found the steering vague they complained of lack of

feedback well the information it was like that story about um owl a tiny creature a mouse went

by owl's house and he heard a commotion and he told his friend owl was up in there throwing the

furniture out of the windows and stomping in the bottoms of all his pots and pans when the signal

is transmitted through several repeaters the signal at the end may not be the same as the

signal at the beginning and so they said if there are gears cams and linkages heim joints

rose joints uh things that have to be lubricated with a grease gun it's going to take the feel

out of the front end but like mark says it's a perfectly adequate motorcycle in other respects

but it failed to make a revolution there was no reason to build it that way having to do with

superior performance other than i'm sure it has a good braking distance

so this is uh this brings us to the present moment when uh i was in the press room at

valencia once and a gentleman came over to show me a project that he was uh i think a

machine shop instructor and he and his lads were building a high tech front end for a motorcycle and

i said well now i'm puzzled because people call this high tech but it has never been adopted

at the highest level of motorcycling which is uh world supers motor gp etc oh he said i'm

perfectly aware of that but my class want to build this oh okay fine that's that's okay

but this continues journalism loves to call complex things high tech extra parts

like the nasa guy said if you have a million parts and the reliability of each one is

a million chances a million times it flies and one time it fails you're gonna have a failure every

time so reduce the number of parts simplicity yeah there been this was the lesson that i took from

all of these complexities which is that the motorcycle can't go too far from being two wheels

an engine and a place to sit

and what the mechanist brothers created hydraulic damping at both ends of a strong frame with a

well founded uh swing arm telescopic four cup front it's still not wrong

so all of these excursions have been instructive but they have failed to produce a revolution

some of these bikes um what was the name of the yamaha that uh was built with a with a strange

front end the gts 1000 had the omega frame and um i'm forgetting that fella's name who put it

together it was his idea he was a big proponent um my brain my brain was actually recently

diverted by thinking back to the moto sizz with the the variable trail inserts and the not tell

the flex adjustable fork on that that was a interesting time as well um that that could

be part of a podcast in and of itself well there are people who've devoted years of their

lives to these projects and we have to respect that um but it does turn out sometimes like

carrying the fuel under the engine it just doesn't work why didn't it work because people were

confusing the sense of security that they have on a heavy motorcycle if it has a low center of

gravity like a harley big twin confusing that with a low center of gravity on some a sporting

motorcycle because as it turns out people imagined if this is the ground plane and this is the

motorcycle people imagine that the motorcycle pivoted around the line of contact of the two

tire footprints it does not instead what happens is the bottom of the motorcycle

goes one way and the top of the motorcycle goes the other so what does it do it rotates around

its own center of mass when i was learning to ride faster and riding more and more hours i

discovered that because you would see an object in the road you wanted to avoid and you didn't

steer around it per se the center of gravity can could continue in very nearly the same direction

it was going but you would swing you would actually swing the wheels out of the way it reminds me

of sports the center of gravity of the motorcycle wants to travel in a

relatively smooth line and things are pivoting around it your wheels are going out the rider

is doing things to alter where that center may be but you're you're trying to carry the center

in a nice smooth manner down the road well it insists yeah and it does and you don't want to

well you have to and like how do we best control it reminds me of sports if you look at a surfer

doing crazy things on a wave if you follow the path of their head their head is relatively stable

because it's just like the squirrel when the squirrel gets flung out of a tree the first thing

it does is it's could be flailing about it's sighting its landing and then it's rotating its

its head is everything and that's just that's sort of where the center of mass is in in a bike you

swing the wheels out just as as you were describing you need to miss the screw you see something you

just go you turn a little bit you get the bike swung and then yeah you allow it to get the wheels

around the outside of it and hope you don't hit what you're trying to avoid but yeah and return

to equilibrium yeah and it's what right back under his yep so it's um it's not intuitive

unless you um have a little familiarity with Isaac Newton and his his work

he seems to have been a peculiar fellow yeah he complained once that all my friends he said

are constantly trying to embroil me with women

so Newton's laws are just what we found happens most frequently

and we call that a law it's more of an expectation and well so what was happening when they put the

fuel on the bottom is they moved it away from the center of mass therefore changing what was more

like a cannon a 24 pound cannonball into something that was more like a 12 foot long

24 pound ladder you're moving masses away from the center of mass so that Freddy's efforts to

change direction produce less result so then they took the gas out and put in two quarts

and they put 32 pounds of ballast up among the pipes and Freddy went sailing through

the orange cones without knocking down one so um good stuff I um I'm pleased with that well you

uh like in many things in life mythology is very easy to uh say is you know yeah

that's how it is just like you talked about moving the engine to the rear

no I got to get traction we got to get traction and drive you know all that stuff

and um McCann's brother's doing science testing actual things and really just

check your prejudice at the door forget your bias just look at what's going on

and you know whatever it is engine building look at the marks on the bearings look at

measure the temperatures I don't know you just send the oil in for analysis what's

what where particles are in there truly so companies do it all the time I'm a firm believer

I got my little black bottles and uh you know I rebuilt the engine of my Ford 460

and it's relatively low miles and I know what the service interval is recommended

and I changed the oil and I've I've got a vial that I'm going to send in and I did it at the

interval and I'm gonna see what happened knowing how I drove it knowing that it's relatively new

but I'll track it and it's it's relatively inexpensive but it gives you actual information

it's not just as you pointed out we talked about oil change interval and I actually I believe the

first time I had this comment from you was reading your book the sport bike performance handbook

it's a great book if you can find it and it's my first try Kevin it's a nice book it's got

hand drawn graphs all kinds of neat stuff that's very artisanal and I like it I loved it actually

it was a craft paper and and one of the things that one of the things that you said in that book

about oil change interval was well you could change your oil every 10 minutes and wouldn't that be

something it was along those lines about frequency of oil change so it's good to know the truth if

you if you can go to the effort and spend the money you know spend I think it's 40 bucks or

something you can send a nice big oil sample in and get some actual data the sensor that

causes the change oil soon light to illuminate what does it measure is it measuring oiliness

oh this oil is terrible does it measure viscosity maybe the viscosity improvement agency agents are

uh which began life with long chains have now become little short things no what it measures

is the presence of anti-wear because as long as there's anti-wear in the oil additive that has

not yet been consumed in the process of protecting metals from each other when they come very close

what that additive does is it produces a sacrificial solid lubricant layer which is scuffed away but

it immediately reforms because that area is hot and the additive it's still in the oil says oh

here's my chance and as long as there's anti-wear additive in the oil uh it is not worn out now there

is another phenomenon called falling out of grade which is exactly what i mentioned before namely

the vi improver is a long chain chain molecule viscosity index vi yes like like um i think of

of oil is like a pot of boiling spaghetti and when you want to thicken a light oil in order to have a

multi-grade 5 w 20 for example you start with five and you boost it to 20 by putting these

long chain molecules into it now if those molecules are not the high quality kind and i forget which

one that is they can break they can lose molecular length and then what happens is called falling

out of grade it's becoming more like a 5 w 5 than a 5 w 20 and you don't i think i took that out of

my pressure washer because i bought a used pressure washer and i don't think they ever change the oil

but also i think the carburetor may have been putting fuel into the oil as well so it was

definitely out of grade and we're um off the subject here but i was just thinking that but you

know we we were talking about trying to know the truth and that's what we uh that's why we send

our oil in at least once in a while and uh to find out what's going on see what's in it and um

well there were those uh there was that b 29 crew who were refusing to fly and a jeep comes up

and screeches to a halt and a red faced officer piles out you will fly that airplane and someone

said yes but uh they gave us engines from bendelair depot i'll have you know that those

bendelair depot engines are just as good as the ones that come from new jersey and he's

ranting and raving meanwhile the pilot has said to the flight engineer you want to go

pull the screens on number three and he's out there doing it and the red face is getting redder

and redder court marshall is about to convene at least in his imagination and here comes the

flight engineer with the screen with bolt heads and pieces of piston ring on it and he

oh i'll fly that no i won't i'll fly it myself yes sir you first know i know i've told that story

before but it's a good one well and you know i haven't agreed oil it's a crude form of oil

analysis pull the screen and see what's on it well cut open your oil filter yep yeah the nascar

nascar guy's cutting the filter open oh no is yeah i mean you can stretch out the paper to see

what's on oh yeah the lab the lab that that does the uh oil analysis for the stuff that i send in

you can also send a filter in and they'll uh they'll dismantle it for you but you could just cut

it open you can get your big pipe cutter and cut your uh can off i mean i i have the fortune of

having so many canister filters in my life i don't have to cut the can off because it just comes off

and makes a mess anyway even the toyota the newer the newer toyota that we drive has a canister oil

filter i thought i'd never get away from it and i guess i haven't but um it is it's good to try and

find the truth well that's if yeah that's it we uh we covered swing arms both front and rear and

alternative alternatives uh we we managed to skip um dr john wittner a little bit of him on his uh

slightly yeah well we'll get to him i think john wittner could be his own podcast

well he sure could yeah there's so so much going on there and the allegiance his father was an aeronautical

engineer and a very practical one oh good see that makes sense doesn't that make sense yes

but uh hasik and there was the troll front end uh troll engineering that was kind of like a

oh consider your tracks on your closet door but for giant doors and the metal rollers and it had

this blade with v's on either side of it it had wheels that located it and there were rolling

elements instead of a linear bearing yeah and i rode one of those it had a very rigid

tubular front end and kind of like almost a miniature trellis that was uh fascinating to

we have we have a podcasted about some of that stuff but um we'll see you soon dr.

wittner thank you for riding with us when you get to us thanks everybody for checking us out

and uh we will catch you next time

Rear Suspension Designs That Failed, and, of course, More!

About this episode

section tire

100 psi

two stroke era

lateral flexibility

TT

rigidly connecting the steering head to the axle

Norton featherbed frame

twin aluminum beam

ride the bike until it does something wrong

limited area

Daytona infield banking (turn five)

front suspension compresses

Yamaha TZ500

Yamaha TZ 750

Honda NSR 500

shortest braking distances

pivoted front suspension

BMW Tazy

racing riders on racers on tasey or similar bikes

repeaters

gears cams and linkages

four cup front

oiliness

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