Why the TELESCOPIC FORK keeps WINNING—Alternative front suspension FAILS!
Moving the problems! Alternative front suspension has some advantages over the telescopic fork that's on nearly every motorcycle made today—front swingarms, Hossack, RADD, Troll Engineering, girder—but these other designs never take over. Some problems are solved, but new ones emerge! Technical Editor Kevin Cameron has seen them all and Editor-in-Chief Mark Hoyer has ridden many. Why does the telescopic fork keep winning? Listen to the Cycle World Podcast to find out.
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00:00Welcome to the Cycleworld Podcast. I'm Mark Hoyer, Editor-in-Chief. I'm with Kevin Cameron, our Technical Editor.
00:06Today we're talking about why the telescopic fork keeps winning.
00:11We've tried all kinds of alternative front suspensions, all the way back to the Nira Car and before.
00:19Nira Car, look it up. It's a pretty funny looking thing.
00:25Apparently they ride pretty nice.
00:30Why does the telescopic fork keep winning and what have we done...
00:35There he is.
00:37What have we done that's different?
00:39I've ridden a few alternative front ends.
00:42There was a Hans Oosterhof who did Hyper Pro.
00:45He was a WP engineer and went off on his own and built the TRX,
00:50the parallel twin Yamaha TRX 850 circa 1995-96.
00:57It sort of had rollers on V-shaped tracks.
01:02It was sort of like a gate track or a barn door track, except it was at a steering angle.
01:10Got Redistiction, Bermuda Tazes, GTS 1000s, Rad, James Parker.
01:18There's all these things that happened.
01:22What do you know, Kevin?
01:24Well, I think that it's clear that there's been a lot of dissatisfaction with the telescopic fork.
01:33I would divide that dissatisfaction into two parts.
01:38The part that is real, such as stiction, which makes braking distances with a telescopic fork longer.
01:47And those things which are based on misconceptions that we have had about the motorcycle in the past.
01:58For example, much thought and development time has gone into a lot of anti-dive systems.
02:07And the traditional telescopic fork, because it has a rake angle, is pro-dive.
02:14So when you apply the brakes, part of the braking force is slowing the motorcycle down.
02:20And another component is causing the front suspension to compress.
02:26But it's moving up and back.
02:29So part of the braking force is causing the front end to dive.
02:37And people saw this as being undesirable.
02:41And you probably recall, many of you will, that there were a variety of anti-dive systems.
02:50Some of them were hydraulic, some of them were mechanical.
02:53They've all disappeared now.
02:56And another misconception that has affected things is the idea of lowering the center of gravity.
03:11Now, this was accepted for years.
03:14And I accepted it.
03:16It was an error.
03:19And Yamaha were able to show that.
03:26And I saw it at the racetrack when I went to a Honda RC45 that was sitting outside the Honda pit and inviting me to measure the height of its crankshaft centerline.
03:42So I did, allowing for the height of the stand and all that business.
03:46Then I went to see Rob Muzzy and I said, I just measured the crankshaft height on the RC45.
03:52Can I measure yours?
03:54He said, oh, yeah, that'd be interesting.
03:56Well, we found that the RC45, which was touted by Honda advertising as being narrow, allows low center of gravity, was like two and three eighths inches higher off the ground than Doug Chandler's inline four.
04:17And so it became clear that low center of gravity wasn't holding Miguel de Hamil back.
04:26And efforts to lower the center of gravity, such as when Elf Honda placed a fuel tank under the engine of the first NSR500 in 1984, it was a flat failure.
04:45Only when they put the mass of the fuel back up where it had been, were they able to match the slalom performance of their conventional three cylinder, which had its fuel above the engine in the conventional place.
05:01So that's why I'm saying that there are two parts to this dissatisfaction with the front fork.
05:10The real part, which is stiction, and also you could say that the fork tubes are, being a cantilever beam, they're subject to all sorts of bending.
05:22And the other part of the dissatisfaction, which was imaginary, namely the low center of gravity argument and the argument that we have to eliminate brake dive.
05:36Because brake dive is actually valuable, it shortens braking distances by lowering the center of mass, which is normally somewhere around 20 or 22 inches above the pavement.
05:50When the front end of the bike dives, it may lower the bike by three inches at the front.
05:58And riders regularly apply the rear brake a moment before the front, because the rear caliper is reacted to the swing arm, it compresses the rear suspension and lowers the back of the bike.
06:12And that was Kenny Roberts' lesson to Skip Axlin when he came to complain that this fellow from Georgia is outbraking me in Daytona practice.
06:26Namely, what's his name? I'm forgetting his name. Sorry about that.
06:35But those two were the driving forces, the real and the imaginary dissatisfactions with the telescopic fork.
06:44And there has been a wonderful flowering of many different ideas.
06:53And one of the most radical is the one that you'll see on Bermuda's TASI, which means thesis, is the hub steerer.
07:05Imagine that you build a front hub with rather large bearings and a large hole through the hub.
07:12And you place a kingpin inside the hub, pivoting on bearings in the hub and tilted back at a rake angle, with extensions coming out through the large holes in the hub.
07:29Such that the front wheel can be steered without steering the whole apparatus.
07:37As you know, with a telescopic fork, you steer the fork crowns and the fork legs and all that business.
07:44So that was thought to be the very next thing.
07:49But when it went racing, it wasn't.
07:54And about all that people could come up with to say about it was, well, the steering feels vague.
08:02I'm not sure what the front tire is doing.
08:05Well, that's everything though, right?
08:07That was really the problem.
08:11We did a comparison test with the ST1100 and the GTS1000, the Yamaha center hub, the RAD design.
08:19And one of the chief complaints was contact patch information.
08:24We just weren't getting it.
08:26But on the flip side, it was like, wow, can you late break this very heavy sport touring bike in a way that would be, we said, potentially perilous on a tele-forked bike.
08:38So you could really late break.
08:40And that was what I found with the HyperPro design, which was the rollers on a gate track with a fixed frame bolted to the side of the engine.
08:51You could change the rake.
08:52You could change the trail with just a few adjustments.
08:56Was that suppleness during braking.
08:59Just no binding whatsoever.
09:05It's probably important to talk about how fork dive is information also for the rider.
09:11Because if you have a well set up fork, you do get dive, but you also maintain a degree of travel, working travel still.
09:20And so you are braking hard.
09:22You have a little bit of tire.
09:24I've watched the tire.
09:26Nicky Hayden in turn 11 at Laguna Seca outbraking, trying to outbrake.
09:33He did everything.
09:34And you watch the tire in slow-mo and the tire was like this.
09:36And then it hits the bump and then you see light under it.
09:40He'd used everything braking that hard.
09:43Yeah.
09:44And the suspension was rigid and it bounced over the bump and caused air time.
09:50Yeah.
09:51But dive is important information for racing riders and street riders.
09:56You have an idea about how hard you're braking.
10:00People used to say of Mick Doohan that he wished his handlebars could be extensions of the front axle so that he could feel every detail of the motion.
10:18On the other end of that scale was Luca Cattelora.
10:21He liked dive because he got information from it that was essential to his way of riding.
10:31But there are so many ways of riding.
10:34I've always thought of my arms as an extension of the front suspension.
10:38Because if you ride rigidly and you squeeze the toothpaste out of your grips and you lock your arms either out of tension or fear, then you are having an influence on the ability of the front end to do things.
10:52If you're holding the bars, you don't get that minor feedback, that delicate feedback of what's happening as you're leaning the bike and you're feeling all of those things.
11:01You're taking away that information.
11:03Your elbows and your forearms, you're an extension.
11:07If you want to reduce it, that's what's exquisite about riding a motorcycle is how in touch with it you are.
11:16You are a moving part.
11:17You are a moving part.
11:19You're hanging off.
11:20You can really have an influence.
11:23Hilariously, when Kevin Schwantz was doing his NASCAR thing, I think he was driving trucks or bushcars.
11:30I don't remember.
11:31But they had an in-car camera.
11:33And he would go into a corner and his leg would stick out inside the car, his left leg.
11:39I saw that on TV.
11:42Mind of its own.
11:43I saw that on TV.
11:44But you could compensate for so much as being part of the machine and having an influence.
11:51You take a guy like me, getting on a race bike.
11:55I'm 225 pounds.
11:58Put me on a 286-pound, 500cc Grand Prix bike.
12:03Heck, we're almost the same weight.
12:05Almost.
12:06I'm going to have an influence.
12:07Yes, sir.
12:09Taco short of two Pedrosas, that's what I used to say.
12:12Just one more taco and I'm two Dannys.
12:15But then again, there were all those people who were outraged that Danny Pedrosa didn't have to carry ballast.
12:25But of course, the motorcycle was tremendous ballast for such a small man.
12:30And I don't think there's any merit in that argument.
12:35At any rate, at the time, and most of this business was happening with intensity in the 1980s,
12:44I felt for a long time that there must be some results from all of this.
12:51But it wasn't the result that I was expecting.
12:54The result was best described by Honda's experience building bikes with ELF,
13:03with Honda factory engines for 500cc Grand Prix racing in the 80s.
13:10The rider was Ron Haslam.
13:12And they got well up in the championship a couple of times.
13:19But each year the motorcycle was revised, was updated.
13:25And based upon the rider's comments and the lap times and whatever instrumentation Honda had on the motorcycle,
13:34each year the front suspension moved away from radical alternative back toward McPherson strut and telescopic fork.
13:48And he went faster each time.
13:51And the comments were more positive with regard to the fork as it morphed back towards convention.
13:59And the radical let's change everything people, the André de Cortens, for example,
14:07the French Formula One engineer who sort of started this business with ELF of applying Formula One technology
14:16to motorcycle front ends, it didn't take.
14:23And I think that the simplicity of having only one pivot in the system, namely the steering head,
14:32and it is rolling bearings, puts the rider in best touch with what the footprint is doing,
14:41with what the tire's condition is.
14:44And when it comes to stiction, I remember talking with an Ohlins engineer in the early 90s.
14:52And he said, well, those fellows keep building those suspensions,
14:56and we keep finding ways to make our surface finish slicker and our coatings harder.
15:03So we're gradually fighting against stiction and winning the battle.
15:09Titanium nitride, diamond-like carbon, all of those beautiful coatings.
15:15I think it would be good to, I have two questions.
15:21One is, why did we move away from girder forks of the 30s?
15:25And then why were initial motorcycle forks arranged the way they were,
15:32which is female sliders on the bottom?
15:38And then we eventually evolved into the inverted fork where we put the outers,
15:45the female on the top, and had the male slider.
15:49But I'm curious about, I guess, the 1930s question.
15:53Like girder fork was beautifully supple.
15:56Is that a Hossack?
15:59Well, the normal girder fork has fork crowns.
16:05And the A-arms or the four levers, parallelogram levers that allow vertical motion,
16:11and not very much of it, typically an inch and a half,
16:16were pivoted with the steered assembly.
16:21Whereas with Hossack and the various double A-arm systems,
16:28the pivots are at the apexes of the two A-arms,
16:34so that there is a member there that steers.
16:38And often there's a link that goes back to a set of handlebars
16:42where the rider happens to be located.
16:44For example, on the late model Goldwings.
16:48Yes.
16:49But back to the demise of the girder fork,
16:56it was the coming of more powerful brakes
17:00that led to things like breaking links and crushing the life out of the pivot bearings
17:07and developing all sorts of looseness everywhere.
17:15Of course.
17:16Yeah, worn out girder is a terrible feeling.
17:18I've ridden those.
17:20Yes.
17:22They're all close to 100 years old now.
17:24And boy, if they haven't been rebushed and redone,
17:27they are terrifying.
17:28Lots of dimension going on there, things that you don't want happening.
17:32And, of course, there are charming stories.
17:34I knew a fellow who was a Vincent advocate who said,
17:41there's nothing wrong with the Vincent fork,
17:46provided that the bushings were properly reamed by so-and-so,
17:52a long-gone employee of the company who used a planishing broach,
17:57no bike built on Monday, but otherwise they were sweet.
18:03Well, thank you.
18:06Well, thank you, Josh.
18:08So that's question number one.
18:12Question number two is why were the bottles, as some people call them,
18:19put on the bottom?
18:20And I think the reason was that seals weren't that good to begin with.
18:24So we just needed a bucket to keep the oil in.
18:26You have a screw at the bottom and you can seal that,
18:28but the seal on the tube is just not that good.
18:30And so let's make a cup to hold the oil.
18:34That makes sense.
18:35Yeah.
18:36And so was born what we would call the conventional fork.
18:40Yes.
18:42And that was quite satisfactory until around the 90s.
18:48And as usual, innovation came from off-road.
18:53And people noticed that when a fork failed in bending,
18:59supposedly Gary Nixon folded a set of 36 millimeter tubes on his KR-750
19:06Kawasaki in 1976,
19:09the crumpling takes place just where the tube emerges from the bottom fork
19:14crown.
19:15That's the point of maximum moment or leverage.
19:20And thus it makes best structural sense to put the large diameter tube up
19:26there and the small diameter tube connecting to the front axle.
19:31And that's all.
19:32Yeah.
19:33And that's where the inverted fork is born.
19:34And we turn the cup upside down.
19:36And so if you have a 43 millimeter male component to your fork,
19:44and that's on the bottom,
19:45then naturally the upper is going to be some diameter larger than that to
19:50contain it.
19:51And then you get that stiffness.
19:53And there was, you know,
19:55the bushings tend to have a little bit more clearance in an inverted fork
19:59versus a conventional.
20:02But, um, well, there's quite a lot of clearance to begin with.
20:07As I learned, um, I got my,
20:10my 1976 KR-750 Kawasaki and I went through the front fork,
20:16um, before the, uh,
20:19racing started and it had separate Teflon bushings in it.
20:24And aha, I found 5,000 diametral clearance.
20:30I can fix that with shim stock.
20:32So I shimmed them up and we went to Loudon for a test day and the rider
20:37came in and said, the front fork's seizing up.
20:40Yeah.
20:41Okay.
20:42We need 5,000.
20:43Yeah.
20:44Write that down.
20:45Yep.
20:46And more for, uh, more for an inverted fork.
20:48And when I asked the Ohlins technician about that, I said,
20:52hoping not to sway the, the number either way.
20:57Um, I said,
20:58what would be a correct diametral clearance for front fork assembly?
21:03And he, he said, Oh, about, uh,
21:06basically it came down to 5,000th of an inch.
21:10I forget what he said in metric, but, um, then I thought, ah,
21:14I feel better now because nice to, uh,
21:20nice to find the same answers in different labs,
21:24in different parts of the world, then you can believe it.
21:28So, um, in MotoGP,
21:32they have both the upper and the lower now are,
21:35are a carbon fiber composite with metal, uh,
21:40wear surfaces.
21:41Um,
21:42Honda did that first in 1984 with that first NSR 500,
21:49it had carbon tubes reputed to have cost 40 grand a piece.
21:56And, um,
21:58never fearful of, of, uh,
22:01spending a little money to see if there could be an edge involved.
22:05So that,
22:09that presented us with the, uh,
22:12the present type of fork,
22:15type of fork,
22:16which I expect to continue dominant because it makes so much sense now that
22:20we have the seals to contain the fluids is structurally the better option.
22:25Well, the stiffness is, uh, you know,
22:27the stiffness between the handlebars and the axle is incredibly important to
22:31how the bike feels and how quickly it feels in steering.
22:36You know, if you ride a motor, I mean,
22:38going back to the eighties where the fork, the fork brace, you know,
22:41we were all bolting fork braces to our lowers just above the fender to,
22:46to help the structural, uh,
22:48stiffness because axles were, you know,
22:50they were pencils back in the day.
22:52They were tiny millimeters.
22:54Yeah.
22:55I mean,
22:56it's just,
22:57it was ridiculous.
22:58And so the same motorcycle with the same steering geometry,
23:01stiffening it between the handlebars and the axle makes it feel like it's
23:06steering faster because it is because you're putting the input in and that
23:11gyroscopic effect is going now and it's resisting.
23:14And then it starts to go.
23:16Whereas it was something very rigid.
23:18Um,
23:19it just happens right away.
23:21And that is one of the great benefits of lightening the wheel because you get
23:25a, you get a double benefit.
23:27You get the linear acceleration and the rotational acceleration,
23:30and then you're reducing those.
23:32That is the bike will accelerate faster.
23:36And then a light,
23:37light wheels.
23:38The gyroscopic effect is so much lower.
23:40I wrote a,
23:41a GSXR 750 that had a carbon fiber wheels on it.
23:47I wrote it at Willows.
23:48I wrote it at Willow Springs.
23:50And the bike itself was in the 330 pound range.
23:55It was an incredibly light GSXR 750.
23:59I couldn't believe it.
24:01I could not believe the way that bike steered and how,
24:06you know,
24:07having lapped on something else before something conventional 420 pounds.
24:11And,
24:12you know,
24:13slovenly cast aluminum wheels,
24:16um,
24:18complete recalibration of your perception of where you are in the corner and
24:21how much input and when it's happening,
24:23just everything happened right away,
24:25but that stiffness from the handlebars to the axle.
24:27And that's why we've seen axles,
24:29uh,
24:31you know,
24:32old axles were solid.
24:34Yeah.
24:36And now they're just big,
24:37they're big thin wall tubes and they just keep making them bigger.
24:40And I think,
24:41you know,
24:42if I'm,
24:43if I'm riding a race bike,
24:44it's like,
24:45is there some kind of,
24:46you look at the width of where they're grasping the axle and,
24:49you know,
24:50it used to be something like this and now it's like this much wider.
24:53Sorry.
24:54I'm making motions with my hands.
24:56Double pinch bolts.
24:59So you're,
25:00you're really trying to stiffen all of that up.
25:03Because one of the things that,
25:05uh,
25:06um,
25:07people in 600 supersport used to have happen at Daytona all the time
25:11was they'd arrive at a corner and the handle bar,
25:15the brake lever would come to the bar.
25:17And of course they would instantly take another bite and there would be
25:21lever and they could get stopped or just run wide.
25:25But what was going on was if,
25:28if this,
25:30the fork you imagine as a,
25:32a pair of,
25:33uh,
25:34cantilevers with an axle at the bottom,
25:36side force applied to the wheel can make the wheel tilt between the fork
25:41legs by bending the axle and its points of attachment to the lower
25:46sliders.
25:47And we don't want that.
25:49We want your intentions transmitted from your brain to your hands to
25:54happen right now.
25:57And that's what gives these late model,
26:00uh,
26:01recently designed motorcycles,
26:03such a lovely response that,
26:08that everyone exclaims about.
26:12And I'm,
26:13I'm really pleased with that because here are things which have come to us
26:17from the cutting edge,
26:19whether it's in motocross or,
26:21or road race or various other disciplines.
26:24And they have been incorporated in production and they are democratically
26:29available to many.
26:35So,
26:36uh,
26:39for the moment,
26:40there is no competition for the telescopic fork.
26:44And when the various alternatives were tried in racing,
26:51for example,
26:52Claude Fior,
26:53uh,
26:54a very dashing Frenchman,
26:56uh,
26:57created a series of beautifully made motorcycles,
27:01um,
27:02several of which competed and Kenny Roberts,
27:07uh,
27:08who always liked to wander around the paddock,
27:10talking to people,
27:11um,
27:12went up to Fior and said,
27:15tell me about this wacky thing you've made.
27:18And Fior told him,
27:21well,
27:22we,
27:23we have had terrible problems with chatter.
27:25And now with this new system,
27:27uh,
27:28we've eliminated the chatter and Kenny kind of shrugged and said,
27:33okay,
27:34you got rid of the chatter.
27:36Now you got hop.
27:37I was watching that last practice.
27:39So,
27:40and one by one,
27:44when these things were tried and in particular,
27:46the elf Honda program,
27:48which stuck with it for several years,
27:50uh,
27:51whatever points of superiority,
27:57such as shorter breaking distances were never sufficient to make any other
28:02manufacturer want to field anything,
28:07but a telescopic fork.
28:08And the telescopic fork has come a long way since the beginning.
28:15For example,
28:17right after the war,
28:18when Jalera designed their,
28:19um,
28:21unsupercharged transverse four cylinder bike,
28:24500,
28:25they gave it 32 millimeter fork tubes.
28:28And I'm sure the riders must've complained about that.
28:34And somebody did the old triumph test of standing in front of the bike,
28:38facing it with the front wheel between the knees,
28:41and then trying to turn the bars and finding that surprisingly easy.
28:46And not only could you easily turn them,
28:50but they would stay turned.
28:52They wouldn't spring back all the way indicating that it was slipping in the
28:56joints enough to stay where you put it.
28:58So,
28:59yeah.
29:00Who,
29:01who hasn't cartwheeled their dirt bike and taking it up and whack the front
29:05wheel against the tree to try and straighten it out.
29:07Yeah.
29:08Well,
29:09it's an important,
29:10it's an,
29:11that's an important component of reassembling your front end is doing it in
29:15an order and getting,
29:17uh,
29:18leaving the lowers,
29:19uh,
29:20leaving the lowers loose,
29:21tightening the uppers,
29:22leaving the axle loose,
29:23and then compressing the fork a few times and getting all that stuff to say,
29:27be roughly more centered.
29:29I put the springs in last because I want to make sure that it goes full
29:33travel and doesn't get a tight thing at the either extreme.
29:37Yeah.
29:38Because it's very easy to do that.
29:39You find lots of bikes that have,
29:41uh,
29:42that tighten up at the bottom or someplace along the way.
29:44I helped the,
29:45my neighbor is a,
29:46is a young motorcycle rider with a pretty beat,
29:48uh,
29:49Ducati,
29:50uh,
29:51like a six 20 monster,
29:54just horrible condition,
29:56very high mileage.
29:57I mean,
29:58it's a pretty nice,
29:59but,
30:00uh,
30:01it's a good bike for him.
30:02He wanted a Ducati.
30:03We fixed the clutch because the center nut came off while he was riding it.
30:07So we,
30:08yeah,
30:09we took all of that apart and it did that.
30:11And I said,
30:12well,
30:13let's,
30:14uh,
30:15he asked me if the clutch fluid should be orange.
30:16And I said,
30:17well,
30:18I,
30:19I'm not really sure.
30:20He called me because it happened on,
30:21it happened.
30:22His clutch wouldn't pull in.
30:23It's because the hub dislodged and the rod,
30:24you know,
30:25it just locked up solid because the hydraulics couldn't move.
30:27And he asked me if the brake fluid or the clutch fluid should be orange.
30:30And I said,
30:31well,
30:32I don't,
30:33I don't really know.
30:34Normally it's,
30:35it's very close to clear.
30:36I guess it could have an orange tint,
30:37like it was paste.
30:38It was like orange toothpaste coming out of it.
30:40So we fixed all of that.
30:41And then we went to do his tires.
30:43Cause I said,
30:44dude,
30:45you got your tires or,
30:46or like 14 or 12 years old.
30:48We got it.
30:49You got to change your tires.
30:50They were different brands.
30:51I think also.
30:52And,
30:53uh,
30:54so I was helping him with that.
30:55And I,
30:56um,
30:57uh,
30:58we,
30:59which I couldn't figure out why the axle wouldn't come out.
31:03And I figured it out because I undid the lower pinch bolt on one of the
31:07forks and the whole front end went.
31:09So the thing had been crashed and like never,
31:12it had been never been realigned.
31:14And so he wrote it a,
31:16we,
31:17we fixed the clutch and it was the,
31:19the feel and subtlety and smoothness.
31:23He's like,
31:24I can't believe the clutch.
31:25And he's also like the bike rides so much smoother now because the fork
31:28was not,
31:29was no longer twisted and bound up.
31:31Yeah.
31:32Resisting all movement.
31:33So we're,
31:34you know,
31:35it's a,
31:36an extreme form of stiction,
31:37I guess.
31:38Well,
31:39they're in the opposite direction.
31:40I got a call from a man who had a very elderly.
31:44We'll taco one 25 TSS,
31:47which was the road race two stroke single that,
31:50uh,
31:51we'll taco built in the beginning,
31:53in the early sixties.
31:54And he told me,
31:57he said,
31:58I,
31:59I've ridden this bike for years.
32:01And I've updated it.
32:02It's now a six speed.
32:04Uh,
32:05but he said,
32:06it's,
32:07it's never,
32:08how shall I put this?
32:10It's never had any front end damping.
32:13So,
32:14so,
32:15uh,
32:16I took the fork apart and the dampers were made all out of brass.
32:20Ideal sort of home project on the lathe.
32:23And the clearances in them were huge.
32:26All the parts were there.
32:29That you would need for a fork that goes compress easy
32:33returns slowly.
32:37So I just made a couple of parts that closed up the clearance,
32:41put it together,
32:42put the oil in it.
32:43And it felt like a fork,
32:44but it came like that from the factory.
32:46So,
32:47uh,
32:48it's just checking.
32:50Brass is a dream on the lathe.
32:53You know,
32:54it sure is.
32:55It's cuts like butter.
32:58So,
32:59uh,
33:00that's why,
33:01well,
33:02numerous things that have happened to me and I'm sure to you,
33:05uh,
33:06and many of the rest of us.
33:08Persuade us that it's good to check the front end of any.
33:12Like that.
33:13You,
33:14uh,
33:15buy particularly used to make sure that everything is free.
33:18I have to check everything.
33:20I've been thinking about this a long time and,
33:22and,
33:23um,
33:25You should leave.
33:26No questions.
33:27I can't,
33:28I can't I'm riding a motorcycle.
33:29I mean,
33:30what's what precariousness is there to that?
33:32I mean,
33:33there's lots,
33:34uh,
33:35we get factory prepared test bikes all the time,
33:37but I still check.
33:39Is the front tire mounted in the correct direction?
33:42Are the axle bolts tight?
33:44How's the chain?
33:45All,
33:46all of that stuff,
33:47because every,
33:48everybody's human.
33:49You can have incredibly meticulous work being done.
33:52And then somebody's hasn't had their cup of coffee.
33:56It's Monday,
33:57whatever,
33:58but we've had test bikes.
33:59So why not check,
34:00especially use?
34:01I mean,
34:02looking at,
34:03looking at my friends,
34:04Ducati,
34:05six 20.
34:06He just was like,
34:07Hey,
34:08have you ever bled the clutch?
34:09Like what?
34:10Like doesn't even know that you're supposed to do that.
34:14How about the brakes?
34:15Have you bled the brakes?
34:16No.
34:17Okay.
34:18Well,
34:19if the clutch fluid looks like,
34:20you know,
34:21toothpaste,
34:22it might be something.
34:23It's all precarious.
34:24We want everything to be good.
34:26Let's check the steering head bearings.
34:27I have that previously 853 mile Ducati,
34:30900 SS.
34:31And I checked the steering head bearings and check the grease.
34:35And,
34:36you know,
34:37you just have to,
34:38you got to look at everything in my opinion.
34:40Well,
34:41I did a short time,
34:42a couple,
34:43three years as an AMA tech inspector and one of the most useful tests,
34:48which I would commend to a street bike owners is to take hold of the top
34:55one after the other,
34:56the front tire,
34:57the rear tire and shake from side to side.
34:59Because if there are any loose pivots anywhere,
35:02you're going to feel them clicking.
35:04It tells you right away.
35:06It's especially important with your Norton commando with ice elastics.
35:10Oh dear.
35:11Yeah.
35:12Because there's so much going on there.
35:14That's maybe ice elastics.
35:16It's its own program.
35:17But,
35:18yeah,
35:19there's,
35:20you know,
35:21the veneer ice elastics were a big upgrade from the shimmed ones.
35:24You used to have to put shims in your big rubber bushings,
35:27allowing the,
35:28you know,
35:29the swing arm and the engine cradle to move inside the main frame.
35:33That's how the commando eliminated vibration,
35:36but remaining in the same plane,
35:38not clicking from side to side or tilting,
35:41allowing this rotation because that's what the,
35:45the parallel twin,
35:46when,
35:47when you,
35:48even when you counterbalance,
35:49it's still trying to do some version of a circular rotation.
35:52Yes,
35:53sir.
35:54To follow.
35:55And that's,
35:56so that's what ice elastics did is it allowed the,
35:58the engine to do this for an aft and up and down sphere,
36:02you know,
36:03orbital.
36:04It was orbiting,
36:05allowed it to orbital orbit without moving side to side.
36:09Although your ice elastics,
36:10you could go closer than 10 thou laterally,
36:13but then you would get more vibration.
36:15And then you,
36:16with the veneers,
36:17you could experiment with putting,
36:19tightening one more than the other.
36:21And the vibration would leave your feet and lots of interesting things.
36:26Anyway,
36:27that's not the fork.
36:30So riding,
36:31you know,
36:32riding the TRX 850,
36:35it was beautiful in some ways.
36:37It didn't seem to have a particularly large amount.
36:39So the TRX 850 was the hyper pro.
36:43The TRX 850 had a lot of v-shaped track.
36:45It was a V shaped track.
36:46And it was all,
36:47it had a few sliding,
36:48a rolling element bearings on a V shaped track,
36:51essentially that,
36:52that,
36:53and that isn't that not sort of what.
36:56Niko Bocker did was at least.
36:57Exactly right.
36:58Yes.
36:59He used a rectangular track,
37:00I think.
37:01Right.
37:02So they're putting a track,
37:03like he's trying to get rid of that.
37:05That torque on the bushings that is causing a heavy amount of.
37:10Contact force.
37:11All the oil out.
37:12It takes a thump to get the suspension moving, whereas if you had rollers in between, you
37:22won't get as much of that thump on the motorcycle and the tire will be able to track the pavement
37:30more easily because there isn't that unsticking force required of it.
37:36That unsticking force can unstick the footprint.
37:40Not the telescopic fork.
37:42So the observation of the TRX was with those rolling elements and not a particularly large
37:49amount of low-speed damping, which is where you're rolling over these kinds of bumps,
37:58these kind of bumps being where the shaft speed would be low or the velocity of the
38:03axle.
38:04Like a square-edge bump that is one inch tall and you hit that, the fork accelerates at
38:08a massively high speed versus rolling along the road.
38:13It had very little low-speed damping and it was really nice to ride for that reason.
38:21You did get good information and you got a very smooth and supple ride in those small
38:26movements and it resisted dive pretty well.
38:30It had a fairly steep angle, I want to say it was like 18 to 20 degrees.
38:34Yeah, it was 15 to 18, I just read about it.
38:37Okay, yeah, 15 to 18 and then the trail was variable, I mean you could adjust the trail
38:43between I think 3 and 4 inches, something like that.
38:46So that was an interesting experiment, it certainly was a prototype, it wasn't production,
38:52you'd have to figure out how to resist wear on the track because on this bike the rollers
38:58were steel and the track was steel and it was V-shaped and the clearances would be very
39:02important there because they would wear.
39:06And the dust seal.
39:07Yeah, and having some way to keep that clean in production would be important, but it was
39:12never deemed advantageous enough for anyone to say I'll buy that and put it on their Kawasaki
39:19or their Yamaha.
39:20Yamaha bought the rad design, the James Tarker, the front swing arm, similar to a Tazy.
39:28Yes.
39:29And again, we said yeah, you can really break the daylights out of this big sport tour but
39:35also it's a little bit vague and getting the bike to change cornering line was another
39:40complaint in that road test about once you were committed to a line it was difficult
39:44to get it off of that.
39:46One of the things that I think should be said about the alternative front ends is that there
39:51are a great many ways to make a practical motorcycle.
39:56And if some experimenter wants to build something, has an idea and wants to build something and
40:02comes up with a well-engineered, rideable front end, there's nothing wrong with that.
40:11The ultimate durability of the telescopic concept seems to stay with us where the difficulty
40:23of control is the greatest, right at the ragged edge.
40:26That's where people are saying, well, I want to feel the front end like my handlebars are
40:34an extension of the front axle.
40:36And the simplicity of the telescopic fork having one pivot only is, I think, its greatest
40:44strength.
40:46And on the other hand, I think it's fine if somebody that's running a machine shop class
40:55for young people sets them a project and they want to try different ideas, I'm all in favor
41:03of that because I'd like to see people get to grips with reality and enjoy it.
41:12To be fair, BMW has continued with the telelever.
41:17There's an R1300GS back there somewhere, still has a telelever front end and that's an A-arm
41:24connected to the frame at basically the height of where the lower triple clamp is and it
41:29goes out with a ball joint to the center of pivot and it adds an element of rigidity.
41:34Having ridden many street bikes with that, what you just said is very true about the
41:40ragged edge of control.
41:42Riding as hard as you can, there's a certain point where telelever becomes vague.
41:48When you really lean the bike over and you're really trying to ride it hard, my experience
41:53is the information starts to go away at that ragged edge.
42:00There's the Haasac version of suspension that's being used on the Honda Goldwing and I think
42:04that's a beautiful application of that.
42:07Yes, because it solves problems there.
42:11It's there for a reason, not just because someone said, wow, this is different.
42:16And BMW continues to use a similar solution on the K1600s.
42:23It's not a telescopic fork, it's essentially Haasac style.
42:31There are places where it's solved a specific problem, but if we want to go win the world
42:36championship, that's not where it's solving the problem, is it?
42:41Yes.
42:42They've gone to bat there, notably the Elf Hondas, a whole series of them over a number
42:50of years, and they got into the top five.
42:56But it didn't seem that it was going anywhere.
43:00Now, it could have been that they didn't have an absolutely top-level rider, Ron Haslam
43:05was a good rider.
43:08He was actually the rider who broke in NR500 race engines during that program.
43:17But there are all these what-ifs that you could say, oh, well, was it the NHTSA that
43:24said a motorcycle with the rear wheel steering is much safer for some arcane reason, and
43:32then nobody could ride it?
43:34Then their response to that was, well, let's get riders who've never ridden a motorcycle.
43:39Well, they did ride a bicycle.
43:41That's contaminated them.
43:43They couldn't ride it either.
43:49Supposedly that's why Auto Union, with their rear engine V16 pre-war Grand Prix car, great
43:55big monstrous thing, got a rider with mainly motorbike experience to drive the rear engine
44:03car, reasoning that he would not be slowed down by inappropriate reflexes.
44:12But those are what-ifs, not something to base a big future on.
44:20Yeah, the high-end telescopic fork is a beautiful thing.
44:25It really is.
44:26It is.
44:27Quality damping and lack of stiction with all these magnificent coatings.
44:31I would love to try a MotoGP front end, even though the only thing taxing it would be my
44:36weight.
44:37Yeah.
44:38They have springs.
44:39Yeah.
44:40Yeah, we do have springs.
44:41But it is, it continues to be the winning solution, and its disadvantages continue to
44:52be solved, or let's say mitigated.
44:55Yeah, handled.
44:57Handled bit by bit, and the advantages remain.
45:00Yeah, namely direct steering.
45:03Direct steering.
45:04That's what we could call it, yeah.
45:07And many of the alternatives are extremely ingenious, and I think we can say that Nico
45:13Bacher and Osterhoff constantly focused on getting rid of stiction almost completely.
45:22I think the latter said that they had 1% of the stiction of a telescopic fork.
45:30Well-
45:31Party in the engineering house.
45:33Yeah.
45:34Right.
45:35So it reminds me of Eric Buell's religious adherence to the rim brake.
45:41Yeah.
45:42You know, yep, it can be lighter, but the pads won't last for an entire world superbike
45:49race, will they?
45:50No.
45:51They won't.
45:52It was a difficult thing for him.
45:53And there were a lot of things overcome there, and all for that lightening of the front wheel.
46:01Well, we have to admire him for the stubbornness that enabled him to stay with Harley Davidson
46:10long enough to have an influence on things.
46:12Now, Harley Davidson is a strange organization.
46:16It's not particularly back when he was there, and farther back when I applied for a job
46:23in the spring of 1966.
46:27They had their way of doing things, and if it wasn't your way, then you could walk.
46:34So I think Eric's stubbornness is a disadvantage when it comes to the rim brake.
46:42It was an advantage in some other areas.
46:47Each of us emerges from the mother with a personality, and we have to cope.
46:55Yeah.
46:56We're just laying the groundwork for the next program, folks.
47:01I think Eric Buell would be the Buell motorcycle, and I don't know, Opus, would be really something.
47:11We will talk about that, because from his time with Harley Davidson and back to the
47:18tube frames, all the way up to the last bikes he made as EBR, that was a really good motorcycle.
47:27Still had the rim brake.
47:28We had problems during testing that the disc wasn't ground flat, and we had to get a separate
47:34wheel shipped out, and they were like, sorry, but it would vibrate heavily under braking.
47:39They fixed that.
47:40There was a self-servo feeling in the front brake, where you would apply the brake, particularly
47:46on the CR and RS, the Harley versions that first came out with the 60 degree.
47:54You would be trail braking, and you would get a servo effect of more, let's say you're...
48:03As you're trail braking, which is braking down to the apex while you're turning, you
48:07would normally have a slow release of the brakes as you're trading cornering force for
48:13braking force, or braking force for cornering force, with let's call it 100% available traction.
48:23You're spending it braking and turning, and you would normally...
48:26The circle of traction.
48:27Right, and you would release as you're coming down to the apex.
48:30What would happen on that version of Buell is that it would be as if you're still squeezing
48:40a little harder.
48:42It was not a good feeling going down to the apex.
48:45They fixed that with the last EBR, and it was basically essentially equal to the Ducati
48:51of the era.
48:52Was that 2014?
48:53It was essentially equal.
48:59So let's make some notes, Kevin, and we'll throw our Buell on the list.
49:05The Buell Opus.
49:06Yeah, that'd be good.
49:07All right.
49:08Well, thanks for listening, everybody.
49:11The telescopic fork keeps winning.
49:13We don't see that changing anytime soon.
49:15We didn't talk about Honda's great experiments with the leading link on the motocrossers
49:20in sort of...
49:21What was that?
49:2284?
49:23God, there were so many.
49:24There have been so many interesting experiments.
49:27I saw that thing leaning against the wall next to their dyno years ago.
49:31Amazing.
49:32Yeah.
49:33Isn't that great?
49:34All those linkages and belt cranks and things.
49:38Yeah, girders, beautiful machined girders.
49:43So many different experiments.
49:44We'll try to mention that Kevin's writing these podcasts into stories, in fact.
49:49So we'll have noted versions of this on the website that you can check out, and maybe
49:55we'll dig up some pictures of that.
49:57I think it was a CR500.
50:01Thanks for listening, everybody.
50:03This was a topic suggested in the comments, so get down in there.
50:08We're going to attack some more of those.
50:12In fact, our next episode will be about KTM.
50:16A massive evolution of KTM from a quirky dirt bike maker into world transportation,
50:24pure mobility.
50:25What is that even?
50:26You know, right?
50:27Yes.
50:28So thanks again.
50:30We'll catch you next time.