The joke goes, "The only way to get suspension to work in the 1970s was to not let it!" We've come a long way, and that was the beginning of the suspension revolution that brings us to today's generally great components and all the world-class stuff going on in racing. Editor-in-Chief Mark Hoyer and Technical Editor Kevin Cameron start with the basic forces at work including what's called V-squared damping (say "ouch!") move to friction dampers and damper rods, and finally get up to the beautiful and easy-to-work on high-performance cartridge dampers on the best bikes of today. And the side stories are almost half the fun. Ride with us!
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SportsTranscript
00:00Welcome back to the CycleWorld podcast. I'm Mark Hoyer, Editor-in-Chief. I'm with Kevin Cameron, our technical editor.
00:07This week we're going to talk about V-squared. What is V-squared?
00:12V-squared damping. Damping in general, how a shock and a fork works on the motorcycle
00:19inside, the magic inside, or the lack of magic, as
00:22we discovered on my
00:2472 Yamaha XS650, which
00:28boings hither and yon,
00:31and makes squeaky spring noises, and probably hasn't had fish oil in them since
00:371977.
00:39So yeah, that's what we're here to talk about.
00:41You know, we're going to talk about oil going through an orifice, and then
00:45controlling the orifice with a valve. So
00:49yeah, lots to talk about in a
00:54small area.
00:57Well, a vehicle is a mass on a spring,
01:02and if you disturb that mass by, in the case of the vehicle, hitting a bump,
01:07and you don't have a source of friction in that
01:11oscillator system, mass and spring, doink, doink, doink, it will keep on
01:17doinking.
01:18And I remember a 49 Ford following the school bus. I could look back at the thing, and the front of it was just
01:26nodding and bowing, and it just went on like that.
01:29Nothing in the dampers.
01:31So in the early days of motoring, of course, all people wanted was something that would run.
01:37And
01:38then they started having races,
01:41and cars without dampers, but with springs,
01:45would sometimes get into oscillations that were uncontrollable, and just
01:50dive off the road and kill everyone on board.
01:54So
01:56before 1900,
01:58the friction damper was invented, which was basically like a miniature clutch
02:04with levers coming out. One lever controlled the steel discs, and one controlled the friction disc. Friction came from leather,
02:14oiled leather.
02:16And then holding this pack of discs together was a big wing nut
02:21on a screw.
02:22Variable damping? Variable damping, that's right. Very advanced.
02:27And the problem with that type of damper was that
02:32getting it to start moving produced a spike
02:36in resistance force, which then fell down to a more or less flat resistance
02:42that was not notably sensitive to velocity.
02:46So what you did with those vehicles was you tighten the damper down when you wanted to go fast,
02:52and if you're riding around town, you'd slack off those nuts.
02:57And then
03:00everybody,
03:01yeah,
03:02everybody in the damper biz. We just got to check the box here and say
03:08sticking friction, stiction,
03:10that's on the list, because you just kind of
03:12went by that. It's very hard to get moving, but once it gets moving, it's pretty linear. Yeah, true. We'll get there.
03:21I think
03:22engineers were aware of the
03:26hydraulic recoil absorption mechanisms on
03:29early
03:31early modern artillery, such as the French 75,
03:35and
03:37they used an oil-filled cylinder
03:41with a rod coming into the cylinder through a seal,
03:45a piston on the end of the rod,
03:48and a hole through the piston so that when the gun fired,
03:52the piston was driven forcefully through the oil, causing
03:57the oil to accelerate to a high speed as it went through the orifice, and thus consuming energy.
04:05And so the
04:06gun would recoil for three or four feet and be brought to a stop,
04:10the whole process was more gentle
04:13than
04:14Napoleonic field pieces, which jumped out of battery with every shot and had to be re-aimed.
04:20So
04:22about 1906,
04:24here's good old Louis Renaud,
04:28his company is still in business,
04:31and he decided hydraulic shock absorbers, hydraulic damping, would be the way to go.
04:37And
04:40even though
04:41his ideas didn't catch on immediately,
04:45those friction dampers under various names like Andre or Hartford
04:50carried on
04:52into the early
04:53post-war years. I think
04:55either Gillera or
04:59one of the other Italian firms still had friction dampers when they started out.
05:06But
05:07here came
05:08the
05:09McCandless brothers, who have invented everything,
05:13and when they built the featherbed chassis for the Norton team in 1950 season, they used Citroën parts
05:23to make hydraulic rear dampers, so their
05:29featherbed bike
05:31had fluid
05:32damping, which didn't suffer from stiction of the kind that the dry friction dampers did.
05:41But
05:42people noticed very quickly that having a simple orifice through the piston
05:47was very upsetting when you hit bumps, because when you hit a bump, the bump throws the bike up in the air,
05:55and
05:56the resistance of forcing fluid through that hole
06:00made it worse.
06:02So it was very upsetting to hit bumps.
06:05So they put a one-way valve in so that there would be damping on rebound,
06:11but
06:12just a simple orifice on compression.
06:17But the terrible fact and the reason for
06:21entitling this episode V squared
06:25is that the resistance of fluid to being pushed through that hole
06:31faster and faster does not increase in direct proportion to the velocity.
06:37It increases as velocity squared,
06:40which means
06:41an exponential curve
06:43that quickly turns vertical
06:46and was responsible for
06:49riders
06:51exiting the infield at Daytona from turn five onto the 32 degree banking
06:58with a great thump.
07:00And it was so upsetting they had to
07:03arrange to have a gear change there so that the rear wheel would be more free.
07:10The shock absorber manufacturers were aware of this and they decided to build what they called a pop-off valve
07:17on the compression side,
07:19which
07:21was a large orifice
07:23closed by a ball or there was a row of orifices around the piston
07:30drilled all around in a circle with a washer sitting on them
07:34backed by a spring.
07:37And either way, as
07:40the
07:41compression velocity of the damper rod increased,
07:46at first it would be
07:48V squared from the simple orifice that we began with.
07:52Then this pop-off valve would lift and let through
07:57a lot of fluid
07:58and it would sort of level off.
08:01And then as the velocity increased, if the velocity increased even more,
08:07the
08:08variable orifice would open more and more so it would
08:13rise at a moderate level.
08:15But when it became fully open, it went back into the same V squared situation. A big orifice
08:23with fluid trying to go through it
08:25would soon become
08:27what they called orifice limited. It would enter the vertical part of the resistance curve
08:33and that's what was happening at turn five. And it was happening worse
08:38in
08:39motocross because in motocross you're constantly
08:43having very large and rapid movements of the rear suspension.
08:50So this brings us up to
08:54the early 1970s.
08:57And
08:58I remember talking to Cook Nelson, who was
09:02the original editor of the refurbished Cycle magazine.
09:07And he had been given a set of racing shocks
09:11and with the shocks came this beautiful damping curve,
09:15which was sort of rounded on the top and a bit flattened on the bottom. Very popular
09:21item in the 70s. We had a shock dyno at Cycleworld and we would run our shocks on the dyno and then that would be
09:28an analysis. And we had to look at this smooth curve
09:32and somehow
09:34square that with our
09:36experience of motorcycles that were quite harsh over sudden bumps.
09:43But then
09:44we could shrug and say, well
09:47the testing machine
09:50is telling us the truth.
09:53But all
09:54all along what was happening was
09:57that where
10:00riding on pavement was concerned
10:02someone in the depths of history had decided, oh the maximum
10:07damper rod velocity can't possibly exceed
10:11X meters per second. So the testing machine was made for that. Yeah, shaft speed. We're talking about the
10:17that's the difference between high speed damping and low speed dampening.
10:21If you're riding along on the road and you have an orifice damper, like he's talking about, and like a damper rod fork
10:28that if you make the compression hole small enough to control low shaft speed, like waves in the road,
10:36you
10:37you make it small enough to do that and then you would get rid of wallow. You wouldn't, you might get rid of wallow.
10:43But as soon as you hit the big bump, that small orifice,
10:47the fluid effectively stops flowing at a point. The ramp of friction goes vertical and it becomes
10:54rigid.
10:55Basically incompressible. You've got a liquid in a container and there might be some air to compress depending on the design.
11:03But you run out of all of that as you possibly have felt before when it goes kabang.
11:08And when you hit a square edge, let's say a two inch
11:11block in the road and you hit that at 30 miles an hour, the shaft speed
11:16of the compression, the axle traveling up, is incredibly high.
11:21And then you think about super cross, what you were talking about, landing from super cross jumps,
11:26hitting bumps at speed with massive amounts of fork or suspension movement.
11:31So if you make then, if you make on the street bike on the fork, you make that damper rod hole big enough to work at
11:39hitting a big bump with a big shaft speed, it's doing nothing for wallow.
11:44There's no damping at around town speed.
11:47Because the hole is so big, the oil is just like, I don't care.
11:51Yep. And so, you know, what we're trying to do is control the size,
11:57basically the size of the orifice
11:59and the volume and velocity of fluid so that it doesn't, well, some people
12:04want to eliminate V squared completely. They want a giant valve
12:10with great big holes in it and then a shim stack to control that
12:14so that you don't get the spike. You can have a small amount of damping at low shaft speeds and then
12:20good controllable damping at high shaft speeds.
12:23The question that I often get is, well, can't you just
12:28fix that on the clickers?
12:32And the problem there is that the clickers
12:35are only adjusting low speed damping.
12:39And that's why in the good old days of road racing in the 70s,
12:44when all these factories were afoot,
12:47there was Ray Plum for Honda, pushing down on the seat
12:52with a
12:53considering look on his face
12:55and
12:56experiencing goes down easy, comes up
13:01and then he would nod to himself and
13:04test completed.
13:05That's, I call it doing it Ray Plum.
13:09And
13:10what you're doing there is you're adjusting
13:14a needle in an orifice to control low speed damping, which is the first part of the curve, first part of the
13:22velocity versus
13:25resistance or damping force.
13:28So
13:30at some point people like
13:33the Fox brothers and some questioning minds at Honda and elsewhere
13:41just happened to have a device handy to measure
13:45damper closing rate and they must have stuck it on a road race bike.
13:51Holy Toledo!
13:53It's not x meters per second. It's x times five.
13:58Well, let's turn up our test machine.
14:02Oh, sorry, we've already got it on maximum. It can't go that high.
14:07Our thinking about damping and the drawing of those beautiful damping curves were artifacts
14:14of an unsatisfactory test procedure,
14:18namely
14:19a damper testing machine that couldn't close the shock or open it rapidly enough
14:25to model reality.
14:29So
14:31people with a budget,
14:34in the 70s there was some,
14:37created
14:39shock testing machines that could achieve these higher velocities.
14:42And when they tested existing shocks on those higher speed machines,
14:48it broke the shocks to pieces.
14:51It tore the damper rod out of the piston or it damaged the machine.
14:57So
14:59over lunch and possibly a beer or two they
15:02considered the matter and realized
15:06that compression valves, even with a pop-off valve or a blow-off valve that I described earlier,
15:14were going into orifice limitation even with the valve all the way lifted.
15:21So for this reason
15:23they turned to a completely different system in which
15:27the washer covering the holes
15:30performed the function of one,
15:33opening and closing the holes, and two,
15:36being the spring itself.
15:39It was either held down at the outer edge or at the inner edge so that the pressure of fluid trying to lift
15:48this
15:49washer off of the damping holes
15:53actually deformed the washer into a slightly cone shape.
15:58And this is what Mark was referring to earlier when he referred to the stack of washers because they quickly found
16:05that you could tailor
16:08the resistance
16:10in its relationship to damper rod velocity
16:15almost infinitely by using
16:18washers of different thicknesses,
16:20washers backed by a spacer, backed by a stiffer washer that came in later in the curve.
16:28People became tremendously clever at this and I used to watch one of the...
16:34I used to enjoy seeing one of the early very experienced technicians in this field
16:41trotting around the paddock with a
16:44piece of wire around his neck on which were all these washers
16:48in their proper sequence for somebody's shock.
16:51Somehow he kept this all
16:56arranged properly in his mind.
16:59But
17:00when you hear people talk about, I had my damper restacked,
17:06it means that the sequencing and the choice
17:09of those washers was changed to alter the curve
17:14of damping force versus
17:17damper rod velocity. Yeah, it's really something. I mean to look at a complicated valve stack or you could have like three stages
17:25what you were describing earlier and you have that first stage where you could just put like one little,
17:29call it one little thin thin shim on there
17:32and that's your low speed, low shaft speed and it comes off nice and easy.
17:37But as soon as you hit something hard
17:39there is a spacer and in a very very small gap is the next spring that does nothing at the small amounts
17:46but as soon as the pressure blows that thing up it
17:50contacts the next
17:53washer, which could be quite a bit stiffer and start to resist what we might say a mid speed.
17:59Yeah, and and then you could you could have a high speed phase or you could do that with the stack alone.
18:06Gil Valancourt of works performance was, he used ball valves and springs
18:13as far as I recall and he was also
18:17he said he used a combination of v squared and
18:23valve damping
18:24in his valve bodies and that he would use v squared as part of his damping curve
18:30and I suppose in it, you know, if you've got your mind on it like your buddy with the necklace of shims
18:36and you paid attention to all the details you would have a feel for that and how that would manifest
18:42itself in actual use. So it's
18:46massively interesting.
18:48What you were talking about with, you know, the low speed damping adjusting with the screw
18:53that is usually the orifice
18:55damping only at that low speed. And you're you're trying to use it
19:00in the in the non-vertical part.
19:03Non-vertical part and what happens why that one reason that works is like well
19:07doesn't that influence the other part of the damping is like no because once that thing goes vertical
19:12it's kind of taken out of the circuit. It's not flowing enough to make any difference at all and it's forcing
19:18the oil to actually go through the valve. So that's how you're
19:22sort of using v squared in the in the low speed circuit in that case.
19:26Motocross stuff now, you know, you have high and low speed damping adjustments.
19:30You got all kinds of stuff on the shock and
19:33and then the valve body. Like the old days you used to have to take your shock apart
19:37and then you'd have to take all the shims off the
19:39shaft or off the valve inside the shock and now they just stick it on the outside so you can
19:44unscrew it and leave the shock in place. In the olden times
19:48or the middle times. What olden times? Yes, in the middle times
19:54when they had
19:55begun to make
19:58bending washer style damping
20:03rear shocks were made with a remote reservoir
20:06that was connected to the damper itself by a small pressure hose and that allowed you to mount your
20:14reservoir wherever there was room for it.
20:17And
20:18in those days
20:19the compression flow
20:22was not driven by the piston but by the piston rod.
20:26The fluid displaced when the rod entered the cylinder
20:31was controlled by its own stack of washers to control
20:36compression movement.
20:38And
20:40later they decided
20:43well, a basic principle is the more fluid you pump the finer the control that you can exert over it. So
20:51they began to make dampers with rather larger pistons and that was especially important in front forks where
20:59there's not a lot of room inside.
21:02But this business of the remote reservoir brings us to the question of cavitation.
21:12Somebody gave me a tremendous
21:15horse syringe, just a monstrous thing.
21:19And
21:20if you filled it halfway with oil it was no trouble at all to just pull the piston back and see
21:27nothingness in there. And then when you let go it would close up and it was like, oh the nothingness disappeared.
21:35That is cavitation.
21:37Imagine the piston moving back and forth in the oil-filled cylinder. If the piston moves faster
21:44then the low pressure side can refill
21:48either through holes in the piston or valving at the bottom.
21:52It will pull the oil apart.
21:55And if the system reverses motion
21:59now we're on rebound, the first thing that's going to happen is it'll close up that
22:04emptiness and hit the solid oil with a thumb and you'll feel that. No control and then you won't like it.
22:13You won't like it.
22:15So they thought, what if we pressurize the oil?
22:19Because then
22:22we can
22:23crush that cavitation down to nothing.
22:27So they found that with 10 or so atmospheres of pressure, that's
22:32150 psi roughly, or a little more,
22:36they could eliminate the trouble with cavitation.
22:40Okay, how do you keep the inside of the damper always pressurized? You add an accumulator. An accumulator is another
22:49cylinder with a free piston in it, not attached to a rod. The piston is well sealed. On one side
22:56is the damper oil and the hose going to the damper body.
23:00On the other side
23:02is gas pressure, which you've put in there through a Schrader valve or
23:06something else you had to pay for.
23:11And
23:13this maintained pressure on the damper oil.
23:18Even as the piston rod went in and out of the cylinder, the motions of that free piston would accommodate the extra
23:26volume of the damper rod entering the
23:29oil-filled chamber.
23:31So that crushed
23:34cavitation out as a problem.
23:38But then they thought,
23:40oh, we're getting complaints from riders that our
23:44compression damping is crude,
23:47it isn't working well.
23:49Maybe we need a larger compression flow.
23:53So they hit upon the idea
23:56of
23:57having no valves or washers on the piston at all,
24:01and simply pushing fluid back and forth through a valve body that was piggybacked onto the damper
24:09in which the washer stacks
24:11were located. One for compression
24:14and one for rebound.
24:16And easily accessible. You didn't have to
24:20take the whole shock apart, dump out the oil, spend your days with your hands feeling
24:26sickeningly warm
24:29from
24:30being immersed in oil at all times. Instead, it was a fairly surgical
24:34operation.
24:36And that's pretty much where we are
24:39today.
24:40There are other ways of accommodating the volume of the rod going in and out of the damper cylinder. In the early days,
24:49for instance, if you ever rode a bike with girling shocks on it, the British made,
24:55I bought a set for my TD1.
24:58It was a
25:00double wall shock.
25:02The inner cylinder was filled solidly with oil,
25:05and the damper rod entered through a seal, and the piston moved back and forth in that inner cylinder.
25:11The outer cylinder
25:13was half filled with oil, and communicated with the inner only at the bottom.
25:18So that as the rod entered
25:20and the fluid in there, where can I go? It went out the foot valve
25:26and compressed the air that was above the oil in the outer cylinder.
25:30Another way to do that was to take some bubble wrap out of a package that you just received,
25:36cut out a little square, and tuck it into the outer,
25:40fill it right to the top,
25:42and
25:43put the cap and seal on.
25:45That way the air in that bubble wrap being compressible would allow the damper rod to
25:52vary the volume.
25:55So,
25:56and then there's a last method of accommodating damper rod, and that's called through rod construction, and you've all seen it
26:04in steering dampers, which have
26:08a rod going in and a rod coming out the other end, and the damper piston is in between joining the two rods
26:16together. So it's a constant volume system.
26:19There's no problem with
26:22having to compress gas or any of that nonsense. It's
26:26also widely used in fork dampers. The through rod damper is popular for forks because
26:34adding the pressure feature
26:37just means more junk going up and down with the wheel.
26:40There have been a lot of interesting solutions. So in your vintage, you know, your 70s, like Yamaha XS650, and well
26:48into modern times, still using damper rod fork
26:52because it's simple, low cost, and sort of adequate.
26:57Racetech has a solution for a damper rod fork called the cartridge emulator,
27:02and that's a pretty neat thing because, you know,
27:05once you've tasted good damping, you get really picky.
27:11And so being able to take a vintage fork and giving it something that resembles cartridge damping,
27:16so what you do there is that you hog out the compression hole on the damper rod
27:22so big that it's outside of the velocity range that you're probably going to hit, and then on the top
27:29so big that it's outside of the velocity range that you're probably going to hit,
27:34and then on the top of the damper rod you put a valve body with a coil spring and a valve on it,
27:42and that closes that area and uses the spring as the compression damping element in a vintage fork.
27:50And then for rebound, using an orifice is pretty adequate, if it's the right size orifice,
27:56because rebound is generally not as wide a range of shaft velocities.
28:01You bet, because it's the spring pushing the fluid through the orifice.
28:06Yeah, and you know, I mean, gosh, everything influencing it,
28:12the movement of the axle and the wheel, the weight of the wheel, the diameter,
28:18how heavy are the brakes, you know, all the things that add up to trying to control the mass.
28:26One of the problems that you can get into with rebound damping, I mentioned earlier that
28:34they decided to have much less compression damping and have most of it on rebound,
28:39so that the bike doesn't get, isn't given as much whammo energy upward on compression.
28:48But if you have 100% of your damping on rebound and you go ride through a bumpy corner,
28:55each bump compresses the suspension, but the rebound damping slows the rebound,
29:02so that as you pass through the corner, your bike is pumping itself lower and lower on suspension.
29:09We're packing.
29:10Packing, yes, and now we're dragging the frame rails,
29:13if we're riding an old motorcycle old enough to have a frame.
29:17And otherwise, it's we're dragging the cases or dragging the exhaust pipes.
29:22And in any of those three cases, you're likely to be lifted up off the wheels
29:28and go sliding in ignominy off the road.
29:32We don't want that.
29:34So there needs to be enough compression damping to discourage that.
29:39There are special places where compression damping, it's a question in the tuner's mind,
29:47whether to use more spring, that is make a stiffer spring,
29:51or more compression damping, the dynamic solution.
29:54One of them is the bottom of the corkscrew at Laguna Seca, which is a kind of a pull out.
30:02You dive down the side of the hill and then you go on to a level.
30:07And of course, it compresses the front end quite a bit.
30:11Well, what we're trying to balance there is the velocity and mass in compression
30:17versus where the suspension is going to settle,
30:21because all the spring does is hold the motorcycle up.
30:24It's going to hold it at a level because the spring has an area
30:29where it's effectively supporting the motorcycle.
30:31There's going to be some preload on the spring, which is there's a free length,
30:36and then the weight of the motorcycle compresses it some percentage, often on a street bike, 20%.
30:42That's the ride height, is how much the spring gets compressed by the load that it's carrying.
30:47But that's what the spring is doing.
30:49And even in the sense of oscillation, if you set up an oscillation with no damping,
30:55if you take the energy, if let's say you're parked and you hit the bike and it goes boing,
31:00boing, boing, eventually it will settle back to its sort of normal state.
31:05So part of the magic with the corkscrew is having,
31:09slowing the compression enough that you don't blow through and bottom.
31:15So you could do that with damping, or you can have a stiffer spring that will
31:20hopefully keep the maximum amount of squeeze from binding the bump stop.
31:26There have been a lot of opinions about this.
31:29In general, Ohlins like to support a bike dynamically.
31:34They want the bike to have suspension that works 99% of the rest of the terrain that you're
31:44covering and not screw that all up in favor of solving the one problem at the bottom of this
31:52steep hill.
31:53Yeah.
31:53Laguna Seca presents a setup challenge, I think, for everyone.
31:59Everyone.
31:59You know, Freddie Spencer.
32:01I've seen a lot of first timers tip over the first time they come down there.
32:05Well, yeah.
32:06Trying to turn the bike and have it nose down at the same time.
32:10And it kind of, Oh, I don't think I solved that equation properly.
32:14Yeah.
32:14Isle of Man TT.
32:16I rode that course in 2017, not as a racer, just as a spectator.
32:21But I was with Freddie, Freddie Dew, who's David Dew's son.
32:26David is the press guy for TT and he does other things, but he was very gracious in
32:31helping me experience the TT in a very thorough way.
32:35And part of that was Freddie and I getting on some borrowed Hondas and riding the course
32:42before racing began.
32:44So they were closing the course, meaning the streets were empty, but we got to haul ass.
32:48We were doing, you know, 80, 85 on, on these Honda street bikes going through the trees
32:52and all that.
32:54The number of bumps and the magnitude of bumps is mind-blowing on certain parts of that
33:02course.
33:03And then the rest of, you know, out in the country, it can be quite smooth when you go
33:06over the mountain and all that stuff, you know?
33:09And I just thought like, how in the, you know, like, how do you set up a motorcycle for this?
33:13And you have to find the window of compromise.
33:16Perfect suspension.
33:17What would perfect suspension be?
33:18It would be a perfectly smooth, unupsetting.
33:22It would be a perfect ride with the maximum amount of grip available.
33:26That's, you would have, you wouldn't, would you feel bumps?
33:30You wouldn't, I don't know, but that's what you'd get.
33:33You'd get a, a ride that doesn't disturb you and you get the maximum amount of grip
33:37available.
33:38You'd need to have wheels that had a zero weight because if, if a wheel is thrown at
33:44your motorcycle at X velocity, stopping that wheel from just clunking at the end of its
33:50travel is going to exert some force.
33:53We'll have to work on that.
33:55Yeah.
33:57Zero mass wheels.
33:59Yes.
34:00Well, I tell you what, it is one of the greatest changes you can make to a sporting
34:03motorcycle or a motorcycle of any kind is light wheels.
34:07I rode a GSXR 750 that had a significant weight loss program.
34:11And one of those was carbon fiber wheels.
34:13And it was a mind blowing difference in motorcycle dynamics and a real lesson for me at
34:19that time.
34:20Just lightening the wheels, you get to the double benefit.
34:24You get a linear lightness, like the straight line, like just accelerating, like your brain,
34:29like your head, your, your body, but it's also rotating.
34:33So your acceleration is better.
34:34Your braking is better.
34:36Your suspension action is better.
34:37You would, you would revalve for wheels that weighed three pounds less.
34:43It's anyway.
34:46When Kenamoto was doing, um, call your carbon fiber wheel supplier at the race, uh, at,
34:54at track side, he, he used rim width as a means of controlling tire grip so that you
35:02could balance it front to rear.
35:05Cause if one tire begins to slip sooner than the other, that puts an end to your attempt
35:10to go any quicker through that corner.
35:12So he had rims in increments of one 10th of an inch of width.
35:20And of course, along came, uh, the rules makers and said, not anymore.
35:26You don't, because this is a democratic sport.
35:33I'm trying to envision him with a necklace of rims.
35:36One 10th of an inch, you know, like he talked about, he talked about meeting a guy at the
35:40airport who is bringing him some, some carbon fiber wheels.
35:45And he said, he looked like a pizza delivery guy because he had these big flat boxes made
35:52me hungry.
35:54The wheel turned out to be too stiff.
35:56That's a, that's another thing is that, uh, people are paying some rider quite a lot of
36:03money.
36:03Are they going to tell him, no, we're, we're not going to make wheels that are, uh, what
36:09you like.
36:09You're just going to have to make the best of it with what we give you.
36:14Um, I think that's, that's a self-answering question, but certainly reducing the mass
36:23of stuff that goes over bumps is wonderful.
36:28For the same reason that the stylus that played, uh, 33 and a third RPM records had to be
36:36extremely light so that it could follow the motion of the wavy grooves in the record.
36:41Oh, it's part of your setup of a turntable is, is getting that weight.
36:45You got your, your screw at the back and you go through the process to make it weigh nothing.
36:50Yeah.
36:51Can't leave her.
36:52And of course, brake discs, uh, in, in 1972, when I built my 750 barn job road racer Kawasaki,
37:04the each brake disc weighed seven pounds.
37:09When we first got our 1974 TZ750A Yamaha, each caliper weighed four and one half pounds.
37:20Now the calipers that, uh, Brembo give supply for MotoGP weigh one pound each and the brake
37:32discs being made out of carbon carbon, which has a density of like half the density of stone
37:40and stone has like close to a third of the density of iron or steel.
37:50Break discs are wonderfully light.
37:52So if you've got either forged magnesium or carbon fiber wheels, you've got tubeless tires
38:00and they've made the tires thinner constantly, both race tires and street bike tires.
38:07And you have lightweight brake discs and calipers.
38:10It can make a tremendous difference.
38:13I put all the junk from the rear end of a, uh, CB900F on the scale.
38:20And I found that what was moving up and down over the bumps at the rear of that bicycle
38:26was weighed 65 pounds.
38:29Yeah, I, um, one of my favorite, uh, one of my favorite motorcycles of, uh, recent times
38:38by recent, I mean, 20 years, but is that, is that XR, the Harley-Davidson Sportster XR1200X.
38:47We have one in our family, uh, the rear wheel assembly with the pulley and everything is 43
38:52pounds.
38:54It's that's a lot.
38:56Yeah.
38:56And you know, that's not a race bike.
38:58It's not dynamically.
39:00It's a lot of fun, but yeah, 43 pounds.
39:03That's a lot going on, man.
39:05Well, uh, when people were dirt tracking, uh, two strokes, of course, a two stroke has
39:14its power is sort of proportional to a, to an organ pipe.
39:18If you blow into an organ pipe at the wrong frequency, it doesn't resonate at all.
39:22So it has a response curve.
39:24That's a sort of a haystack.
39:27And, uh, if you are trying to come off a corner, you'd like your power, your torque to be your
39:38driving force to be smooth enough that the grip on dirt can, can accommodate it.
39:45So guys said, well, let's make the wheels heavier to make the rear wheel heavier.
39:49So that it'll act like a huge flywheel and kind of smooth the engine out.
39:54So they used to fill them, fill the inner tubes with water, and they made a rule against it
40:00eventually.
40:01But I always thought that was wonderful that, that you might get to the end of the race
40:05and the three top bikes are there on the podium and you can hear this sloshing and the water
40:11is still cool.
40:12Water was away.
40:15Dirt track wheels in recent years have had significant mass added to them.
40:21Uh, metal mass at the, at the outer ring where it will have the most effect.
40:25And, uh, I think they have a limitation on that, but yeah, big, heavy, big, heavy wheels.
40:32Um, I was thinking back to what you said earlier about, you know, bouncing on the suspension
40:39and, uh, you can kind of get an idea of a rebound by compressing the rear and letting
40:46it go and saying like counting one, 1000, you can sort of get an idea like, yeah, that's
40:50probably in the ballpark, but it's also important to think that the suspension, the oil is probably
40:57not warm at that point.
40:59And there's no, there's nothing going on.
41:01That's the actual riding condition.
41:03And like you can bounce on the fork, but you shouldn't hold the brake and you can kind
41:08of like look at it and say, yeah, the rebound is, yeah, it looks about right.
41:14Like you get, you would eventually get sort of a judgment for it.
41:17And then you can also feel if like, oh my gosh, the compression is very stiff.
41:21You might get an idea of what's going on.
41:23And then you can kind of like look at it and say, yeah, the rebound is, yeah, it looks
41:28about right.
41:28Like you get, you would eventually get sort of a judgment for it.
41:32You might get an idea of that, but you really need to be five laps in and riding around
41:37and trying to be sensitive to what's happening.
41:40And I think that's one of the, the things that I've observed over observed over many
41:46years of riding is, um, you know, a few clicks on, on a damping adjustment.
41:54If perfect rebound damping gives you the mythical a hundred percent traction or some near,
42:00cause I call it 90% cause it can't be perfect, but good.
42:03Whatever.
42:04Call it, call it a 90%.
42:05And that's the, that's the best that the fork has.
42:09And you're, you're on either side of that and you go a couple of clicks out.
42:15It, it might be 87% and the sensitivity to knowing the difference is really where a lot
42:22of that tester and rider magic is.
42:25And then working with a crew chief and translating.
42:30There are many crew chiefs who do not want their rider to come in and say, I need two
42:34clicks of rebound.
42:36Yeah.
42:37Right.
42:37No, no, no, no, no, no, no.
42:38What's the bike doing that makes you want to say that.
42:43Yep.
42:44And that, anyway, that's one of the interesting things about that very, very ability, variability
42:49and damping is you're talking about a lot of times, very small amounts or in the old
42:55days, like.
42:57Like shock rebound.
42:59Oh, it's adjustable.
43:00It has four positions.
43:02Yeah.
43:02You know, position one is like somehow less than zero.
43:06It's like nothing, nothing.
43:08Position two is like, eh, position three is maybe there's something in four is eh, yeah,
43:15I guess we got some, but it was never enough.
43:18Yeah.
43:20It's so interesting tuning damping also for street bikes versus sport bikes.
43:27And then the percentage of sport bikes that go to the track that actually go to the track
43:32is really low.
43:33Like a CBR 1000, most of those get rattled around on the street, drag raced, wheelied,
43:39you know, sport riding, but actually going to the track is a really low percentage.
43:44So when you're deciding in product development and tuning what to do, it's, it's a real
43:51philosophical decision on how to set it up.
43:54Because like, if you go back to the VTR 1000, uh, SP, the, um, RC 51 and the CBR, you know,
44:03nine to nine, nine 54, those were two philosophies at the same time.
44:10And the RC 51 was more like race damping, more, more, more stiff, uh, more like race
44:18damping nine 54 true to the CBR.
44:22Like Tadal Baba, the large project leader for the CBR 900R wanted the, he always called
44:29it the bigger circle.
44:30So it was light.
44:31It had the 16 inch front wheel, even though the rolling diameter of the wheel was similar
44:35to a 17.
44:36It was do, he was doing all these things to make the CBR like a really great street bike
44:41sport street, you know, it was like to make more riders happier in more conditions.
44:48That was the bigger circle philosophy.
44:51And so the nine to nine, nine, five, four, carry that forward.
44:55And it had more street bias stamping.
44:57It was softer.
44:59I always liked the RC 50 RC 51.
45:01I liked the way that suspension felt.
45:02I felt like it was where, where I want it to be.
45:06And then you got Ducati's and, um, I think one of my favorite, uh, one of my favorite
45:12quotes from a, an old, uh, comparison test, we used to let, um, competing tester manufacturer
45:21people ride each other's bikes.
45:23If there was time and the people had the inclination, everybody had to agree and whatever.
45:28But, uh, one of the guys from a Japanese manufacturer went over to, uh, uh, you know,
45:33nine, nine, eight.
45:34And, uh, and he's like, everything about that bike is hard.
45:40It's just hard because the seat was thin and the suspension was stiff.
45:44And the, you know, the, the riding position on those was pretty, uh, pretty extreme.
45:48And the, you know, the Japanese were not doing that as much.
45:52They were trying to hit a, hit a broader target.
45:55Then like, Hey, here's the thing.
45:59If you, if you put sticky tires on your car, um, about the only suspension response you
46:07can have to that is, um, anti roll bar stiffness, because the tires are going to let you go
46:16faster around the corner, which means more weight transfer to the outside and excess
46:23concentration of load on the outer tires.
46:26But on a motorcycle, the act of going around the corner also compresses the suspension.
46:32So if you're going to have a soft motorcycle for around town, you're going to have a low
46:40rate spring with, uh, enough preload to get the ride height that lets you not drag the
46:50frame through corners.
46:52But then if you decide to take off your, uh, wheelbarrow tires that the bike came with
46:58and put on super sports tires, um, you can now compress the suspension more as you're
47:05going around the corner.
47:07And if you put on MotoGP tires, you're going to be up the Creek because there's now so
47:13much force compressing the suspension that you have to make everything hard.
47:18Well, that's what, that's what was happening there is that the, that the actual, the act
47:25of going through corners compresses the suspension and the better the tires, the faster you go
47:30around the corner, the more it compresses and the more you have to fight against it
47:35by putting in, well, here's some stiffer springs and you slide them down in the oil.
47:40So that one droplet doesn't get you in the eye and it's, uh, you end up with something
47:47you end up with something stiff and you think, uh, I, I wanted to do the occasional track
47:53day, but the main result is I have to pee every 20 miles.
47:57Well, there's, so what you're saying is we, we need to make it, we're getting more grip.
48:05We need to make it, uh, stiffer and we need to, to be able to go around the corner to
48:09race speed, but within that band or in that, in that sphere of performance, what you're
48:16talking about reminds me of two 50 Grand Prix at Daytona.
48:18I want to say in 2003, maybe a classic battle between rich Oliver and a Roland sands.
48:30Oh yeah.
48:31In two 50 Grand Prix and the riding style and philosophy difference of those two riders
48:38is Roland was extremely fast and rich Oliver, like unbelievable.
48:43Rich in, in a way was an incredible total package because he had all of his binders
48:49for jetting every track that he'd ever been to.
48:53He had all of the data.
48:54So when he showed up, he knew what the parametric pressure was for jetting, all of that stuff.
48:59And one of the things he said to me in an interview years ago, he says, the, I found
49:04that the looser I gripped the bars and the slower I moved my hands, the faster I went.
49:11And I think Roland was always like aggro, you know, aggro on his bike.
49:16He was like, and so Roland's bike was very stiff and you watched them go back and forth
49:22at Daytona and Roland's like options.
49:24I, he could do things with his bike, but I think ultimately he had lower grip and rich
49:30would set up his bike to be more supple and give him a greater outright grip, but he couldn't
49:35be as aggressive with it.
49:38And to me, that's a beautiful expression of how many ways there are to win and lose stuff.
49:48I remember that race.
49:49If we're talking about the same thing that Roland was behind, right.
49:54Stuck with him and they went round and round like that.
50:00And at a point, I think Mitch Oliver decided, I don't want to take a chance that this guy
50:09has some kind of plan for the last lap.
50:14So I'm going to have to break this guy.
50:17And he just, he lowered his lap times.
50:20And you could see the pursuing rider beginning to make bigger mistakes and to waste more
50:27time getting them gathered up again.
50:30And finally, he made the rational decision, which is second is better than gravel.
50:36And that's the way they finish with some respectable gap between, but for the first
50:44quite a few laps, they were nose to tail.
50:48And of course, other riders have spoken about that, that looser grip.
50:53Mike Baldwin talked about riding the banking at Daytona.
50:56He said, a lot of people want to be at a certain place on the wall.
51:00He said, I stopped doing that when I realized it was pulling the tack down.
51:06So I let the bike go to where it liked it and I'd see the tack creep up.
51:13It's good to have some brain left over to observe the little things while you're riding.
51:19Yeah, definitely.
51:19There's a testing pace.
51:20You know, when you go out and you want to, you're trying to get a lap time, you still
51:23have to, you have to have some brain left over, but if you're actually testing for me,
51:28anyway, I, I need to back it down.
51:31It's a different pace.
51:33It's still, you know, I hope respectably fast and confident, but you, you really want to
51:40leave the brain power and then have your hands be, uh, you you've got to feel those minor
51:48movements.
51:48You had to feel what's happening and try to discern what's going on at the back and what's
51:52going on at the front.
51:53And the, the slight differences in feeling when you roll the throttle on exiting, trying
51:57to exit the corner and, and, and all of that.
52:00There's another, there's another, there's an energy question here too.
52:03Um, one of the Loudon races that Rich Schlachter rode on my seven 50, um, well, Boston cycle
52:12750, he rode the motorcycle.
52:19Like he was having, uh, judo practice, harsh muscular movements, and he led the race and
52:31he wheezed out because he used more energy than he had available.
52:37So at the end his energy was dropping and the other guys just, I'll, I'll, I'll take
52:42it from here.
52:43And it was, it was disappointing because of course you always want your, your guy to stay
52:49up front there.
52:51Didn't happen that day.
52:52So that's another argument for not holding the motorcycle in a death grip, because how
53:00are you going to tell, how will you hear its questions and its complaints?
53:06Absolutely.
53:08And that brings me to the idea of figuring it out.
53:12If you don't know what too much spring preload feels like, or not enough, uh, if you don't
53:20know what harsh, you know, like too much compression, damping, not enough rebound, all of those
53:26things within the, and except, you know, you don't want to put yourself at risk.
53:30You gotta be careful.
53:31You have to be thoughtful about your changes.
53:33But if you have a motorcycle that has adjustable suspension, go ahead and take your fork and
53:40put the maximum amount of spring preload in your fork and don't change anything else and
53:45ride a familiar piece of road.
53:47And typically if I'm road testing a motorcycle, I will find a section of road.
53:51Like there's a really nice mountain road that's kind of windy and low speed.
53:56And then the other side, it's a big flowing piece of road.
53:59And I would go up and down that.
54:01I'd go up with a certain suspension setting and come back down, think about what I was
54:06feeling.
54:07And that's, that's a situation where I would say, I'm going to wind full spring preload
54:12into this fork and see what happens and see what that feels like.
54:14And then that's when you feel.
54:17When the spring is over compressed, you can feel how it doesn't have the supple range
54:21and you can feel that in your hands.
54:24Hmm.
54:25And you just repeating that with your own motorcycle and going through the range of
54:31adjustment, take, take out all the rebound damping and carefully ride up the road,
54:37incrementally add pace until something happens that you don't like.
54:41Yep.
54:42And this is basically what Mike Baldwin talked about.
54:45He said, uh, I like to start with, with nothing and then dial in rebound until I get what
54:56I like and then add some compression and see how that feels.
55:03Because if you're not familiar with how these controls translate into your super fine drive
55:14feeling, as one of those wonderful manuals of the 1960s put it, you'll never know.
55:21And I see riders who are riding along with their shift pedal too high.
55:27And I think about that crampy feeling you get in your ankle from that.
55:32How can you ride like that for more than five minutes, relax, set up your motorcycle.
55:39So you are comfortable because if you're uncomfortable, your body is going to say,
55:47the first message we have for you is that we don't like this.
55:51The other thing is you should lean over more.
55:53We'll go into the guardrail there.
55:56And you want to have the important messages on the top of the stack.
56:02And that means getting rid of all those negative feelings from bars that are at
56:07the wrong angle for your wrists, control pedal heights that are wrong for your ankles,
56:15things of that nature.
56:18We've come far afield.
56:20Yeah.
56:20Well, if you get, you know, one warning is if you get, if you start to become very
56:25sensitive about your dampers, when you, when you've got your 1995 Ducati 900 SSCR that
56:32doesn't have an adjustable fork and doesn't have a beautifully set up cartridge,
56:36then you find your aftermarket supplier for drop-in cartridge inserts with compression
56:41damping on one side and rebound on the other and your string preload adjustments because
56:46you got to have it.
56:47And I have to say, these are Andriani inserts and they're, I think the retail is about
56:52600 plus you have to install them.
56:54And if you're really doing it, you're going to bush and seal the fork and clean everything
56:58immaculately because that's what you do.
57:00And Andriani has a sonic cleaner that will accept an entire fork assembly.
57:07And so they make it, it's, I believe he said it was $20,000, but you do all that.
57:15And, but for a thousand bucks, you can have a race-ready cartridge fork on your vintage,
57:20whatever you can do that with on your Yamaha R7.
57:23Or you can blow the same money on the weekend at buying rounds.
57:28Yeah.
57:30Which would you rather have?
57:32Or tires.
57:33Yeah.
57:33That kind of thing.
57:36Well, it's too late to talk about chatter.
57:40Well, we can chatter about chatter on another occasion.
57:44Yeah.
57:44We can, we can do a sidebar on chatter in the next round, but thanks again for listening.
57:50That'll, that'll be it for V Squared.
57:52We hope that's enough of a title on the video to get people to listen to this point.
58:00It's yeah.
58:04Learn about your damping, learn about what's on your bike, go through the adjustment ranges
58:08and see what happens.
58:09It's, it's a lot of fun and you can start develop your sensitivity and then you can
58:15start spending money.
58:16But ride what you have and find its limitation before you think you should change it.
58:25Yeah.
58:26That'll save you some money.
58:28Work on your riding first until the bike actually tells you and you understand the
58:34message of what's wrong.
58:35That's a, I think that's a, that's a lesson I learned a long time ago from guys like Don
58:42and Jimmy Lewis.
58:42Like, Hey, how about revalving this fork?
58:46What's it doing?
58:47Yes.
58:48That makes you say that.
58:50Yeah.
58:50I'm like, ah, fair enough.
58:52Yep.
58:53Anyway, thanks for listening folks.
58:55See you down in the comments.
58:56Subscribe.
58:57We do it every Wednesday.
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