Not surprisingly, MD readers tend to be brilliant. The following responses to our Yamaha MotoGP prototype article prove it. You may remember that we asked “What is Yamaha up to?” with regard to their twin-shock, upside-down swingarm, test mule. (Look back at our article for the photos our readers analyzed.)

• Here are the immediate advantages I can see to this design.
  
  
  1) Lighter exhaust with fewer bends. By being able to run right under the bike and up through the swingarm the exhaust length and number of turns can be reduced providing better flow and lower weight, as well as keeping that weight centered.
  
  2) Longer swingarm on a shorter chassis. Without having to make space for a central linkage the swingarm pivot can be moved forward so that shock travel velocities are more constant without having to increase overall wheelbase.
  
  3) Less swingarm flex. With the forces more evenly distributed across the swingarm it can be made more rigid for the same weight since forces aren’t concentrated at the front of the swingarm.
  
  I can see some disadvantages to the system, most of which would be minor and more than offset by the advantages listed above. Such as matching the shocks (which has never seemed to be a problem for front forks) weight carried higher (but not significantly), and it doesn’t seem to make the bike any wider.
  
  I’d love to see Yamaha develop this further and Eric Buell steel it for the next generation of his wild chassis 😉
  

• The idea is that ONE really good shock is cheaper than TWO really good shocks so this is the route to go for cost reasons with the exception of offroad jumping, possibly. However room must be made between the engine and the rear wheel and the swingarm must be made heavier for the same degree of stiffness in the same way that single sided arms are heavier than twin arm setups. A single shock mounts way to the front leaving a long, long lever especially where swing arms might be 22 inches long, maybe getting longer.
  
  
  Moving the shock mounts much further towards the rear axle decreases the lever length decreasing the amount of metal and weight required.
  
  How much bulkier could swingarms have become before someone revisited the concept.?
  
  I have often wondered if the swingarm pivot could not move forward of the transmission output sprocket
  

• Hi guys…I think Yamaha is trying to come up with an answer to Honda’s Unit Pro Link rear suspension…I don’t think the M1 is down on power to the RC211V, but putting it to the ground is another story…I believe Honda’s approach to Tuned Flex in their chassis is an intriguing subject to the Yamaha engineers…Thanks for the great free website…I was suckered into paying for another site that promised the latest scoop on everything…I knew everything they knew 2-3 days prior to seeing it on their site.
  

• Well hopefully Yamaha will be able to better challenge Honda this year. In moto GP with such huge amounts of HP available, maybe handling could be something that gives one team the edge over another. Also, the idea of frame flex is really intriguing- just think of the handling possibilities with tuned flex!! It is almost like a machine that is able to react to different conditions the way a living thing does.
  

• Of course there measuring chassis flex. I´ve have seen companies testing sideway suspension on the frame of speedway bikes, these frames are flexing up to 100 mm sideways in worst cases. Frame rigidly is not always a good thing (do you remember when McGrath made a switch from Honda to Suzuki because he got arm pump with the new aluframe Honda). Speedway bikes got steel frames for a reason. The hard thing is to build in flex where you want it and the right amount. I remember
  when I was riding a Suzuki 1982 1100 the bike had its own life ower 200 km/h. My new aprilia 2002 (I’m getting a 2003 this year) RSV milleR was/is the best behaving bike I have ever ridden (I had a 2000 Fireblade with the “flex frame” as well which wasn’t as good) I have tried R1´and other 1000cc bikes and there all behaving differently due to different suspension tyres and frame constructions. If you take a look at MX-Bikes the only mayor companies who got aluminium frames is Honda, most people that I know prefer Yamaha
  4-Strokes. I think steel frames are behaving better on MX-Bikes (more flex takes away hard blows). Yamaha is a innovative company who likes to test new things with Öhlins here in Sweden. About the twin dampers. I think one of the reasons of twin dampers is to have an even strain on both sides which you don´t get if you put the damper on one side of the frame. In this case they want the exhaust in the middle of the bike which forces the dampers on the sides. Another reason for the dampers on the sides is cooling, Due to heat the dampers are working differently (look at Sachs MX-Damper which
  got fins). I´ve heard of companies who have been testing watercooling of their dampers with various results.
  

• Looks like some sort of computer controlled-suspension?
  

• In your article about the YZR-M1 prototype experiments you asked for reader’s thoughts why Yamaha experiments with twin rear shocks. Well I’m not an expert but I could think of the following advantages:
  
  1. As described in your article, Yamaha is investigating the possibility for frame-flexibility to solve the suspension issues at large tilting angles. Using twin shocks might allow to build-in a-symmetric stiffness, which could be an advantage when more flexibility is needed in a few identical curves.
  
  However, I don’t think that’s the (main) reason since finding the right setup with twin shocks doesn’t make life easier…
  
  
  2. More likely is the whish for more horsepower, especially at high revs. Last year the V5 engine of Honda demonstrated to be (slightly) superior over the 4-cilinder M1. That might explain why the experimental M1 version has this new seat-exhaust with perfect aerodynamics for the acoustic waves high revs.: nicely symmetric, yielding equal path lengths for all cylinders and no additional sharp bends. Furthermore, the bike is more balanced when using seat pipes. Because of this design constraint, no space is left for a single-shock absorber. The logical consequence is to use twin-shocks.
  
  3. But notice that also the link-system has gone, or at least I can’t find any on the pictures. This means that quite some weight-reduction both on the frame and suspension is achieved. Except from the link itself, also hinges on the frame and rear-suspension are massive. The frame and suspension have ‘natural’ stiffness at the outsides. A singe-shock means that additional
  hinge stiffness is required in the middle of the bike. By using twin-shocks, suspension hinges can be built at those spots where stiffness is already available.
  
  Maybe I’m totally wrong but these are just some of my ideas that went through my mind when I saw the experimental M1 pictures for the first time. Keep up the good work with your MotorCycleDaily site, I enjoy it!
  

• Well the first thing I think is that the twin shocks greatly simplify exhaust routing
  for underseat exhaust.
  
  Secondly, torsional (twisting) loads are now handled by the swingarm differently than
  with a single shock. With a single shock, any torsional flex in the swingarm is undamped.
  
  I suspect that Yamaha is experimenting with having more torsional flex in the swingarm
  that usual, and if they used a single shock, the result would be ‘wobbly’ and rear end grip
  hard to get a good feel for. With the dual shock, they can have some torsional flexing on
  the swingarm and still control the swingarm better, and therefore the wheel better.
  
  I’m not 100% sure what effect well-damped torsional swingarm flex would have on handling.
  The bike might feel less sensitive to road imperfections and therefore create more consistant
  grip.
  
  As far as the linkage, I don’t see much room at the top for a linkage, It might be a bit
  hidden at the other end of the swingarm. A dual shock opens up great possibilities there too.
  I’m just trying to figure out if they could do something cool with the linkages, like maybe
  using a single 3-D linkage instead of what we all expect as 2 2-D linkages.
  

• I suggest reading the book from Tony Foale (see http://www.tonyfoale.com/); he describes the lateral suspension (complete file: http://www.tonyfoale.com/book/LATSUS.PDF ), which is analogue to this.
  Furthermore somebody saw a transducer on the other rod (left-side).
  

• Regarding those rods tied to the steering head: I’m not sure that they’re measurement devices. After all, with modern CAD tools engineers have a pretty exact idea how the chassis will flex before it’s even fabricated. My guess is that they’re dampers. Specifically, Yamaha may be experimenting with somewhat dramatic levels of tuned chassis flex, dramatic enough that active damping of the flex is required.
  
  The odd double-shock design may be for similar reasons. A traditional swingarm is designed to allow rotational movement around the axis of the swingarm pivot and disallow independent movement, or flexion of the two sides of the swingarm (which would result in torsional motion of the rear wheel). It’s hard to see how a dual-shock design would be helpful in this case, since there is only a single axis of motion to control. Suppose, however, that Yamaha’s inverted swingarm design intentionally allows some independent movement or flexion of the two sides of the arm. This may allow the rear tire to maintain better contact with uneven pavement when the bike is leaned over, allowing earlier acceleration out of corners. The dual shocks could be used to control this swingarm flexion.
  
  That’s my best guess, anyway, but what do I know? I’m a Honda man.
  

• I think your bang on with most of your thoughts. In the from-rear-action shot, you can see a sensor measuring suspension travel that looks similar enough to the front strut that you think is measuring frame flex from the steering head. Where it attaches to the top shock mount looks less than permanent as well. I think though that Yamaha’s explanation is pure bunkum.
  
  Yamaha can’t have a single shock rear end and still have that large exhaust collector coming up the center. If they stayed with the single shock, they’d likely have a heavier swing arm due to the bracing that they’d have to add. The twin shocks would allow a lighter swing arm, and less unsprung weight … do the shocks count as unsprung weight? Why do they really want the center up exhaust and underseat muffler? Aerodynamics!

  Heck, maybe they just get more sponsor money from Ohins depending on how many Ohlins products they have on the bike at any one time.
  
  Those are my thoughts.
  

• The linkage at the top of the shock is probably a ride height adjuster. The rod, as you suggest, is a linear pot to measure frame flex.
  
  
  The twin shock design provides up the center room for the exhaust and set to each side the shocks get air flow to keep them cool.
  

• It’s obvious to me that MotoGP is going to be the development lab for future commercially released machines. After looking at the Ducati 916 series for ten years, and after seeing the exhaust setup on the new Honda 600RR, Yamaha recognizes the elegance and utility of under seat exhausts and is currently trying to find a way to incorporate the system into it’s showroom lineup.
  
  
  I feel that the twin shocks on the M1 serve a dual purpose. First, it makes sense to me to simplify the suspension design on the bike. After 15+ years of attempting to perfect single shock linkage design, I believe Yamaha when they say twin shocks get the 200+ HP MotoGP power to the ground in very effective fashion. Secondly, the dual shocks simplify the task of routing under seat exhaust. Look at it – it’s quite interesting that they’ve taken a page out of the past to go forth to the future. I for one think it looks great! Unfortunately I think it’s too late to get the setup on to the 2004 YZF-R1…
  

• Why not 2 shocks? Maybe rebound damping in one, compression damping in the other. More total volume than any single shock? Finer control through dual springs _vs_ one?
  
  The fore-aft rods being strain gauges to measure frame flex makes much sense.
  
  All just One JAG’s Opinion. (JAG = Just A Guy)
  
  BTW, thanks for posting the press releases daily. It’s a nice touch to an already fine site.
  

• Looking more closely at the fore-aft rode, looks like they could be frame flex Adjusters! Why not have dampers (like a steering damper) with adjustable settings to add/remove flex for testing? Why not for track-to-track changes?
  
  
  As always, just One JAG’s Opinion.
  

• Possibly for exhaust clearance? www.motorcyclenews.com has a few pics as well.
  
  Did I win the free subscription? : )
  

• I love your site! I visit it pretty much every single day. Keep it up!
  
  About the Yamaha/Ohlins twin shocks, this is what I was able to find out:
  
  – They allow the bike to keep more of its weight low and central;
  
  – They allow the exhaust to take a simpler route, aiding aerodynamics;
  
  – They may improve traction and tire life by reducing chatter under heavy braking;
  
  – The rods tying the rear of the frame to the steering head are actually damper rods;
  
  – Yamaha have patented this new system.
  

• Just a wild guess but I think they may have the entire rear swing arm assembly on a pivot. This would allow the front and rear wheels to respond to road irregularities separately. They would only have to allow for a few degrees of rotation, but it kind of explains the twin shock/spring thing.
  

• They are implementing a similar rear suspension theory that HONDA has already proven with their MOTOGP bike of last year…..and the new CBR600F4i of this year!
  
  Isolating the suspension forces to the swingarm, which allows the rider to get on the gas sooner in the corner. The rod looks to be related (but not part of) the linkage. I wouldnt get too carried anyway with the “frameFlex” notion : fuzzy frame = fuzzy handling.
  
  I would say the rod is adjustable and they are trying to get a feel for how much tension to add in so the frame does NOT flex.
  
  PS: Yamaha owns part of (most of) Ohlins, so they are using TWO shocks….very curious…..if this setup works, and it makes it to production sportbikes, the number of after market shocks required for racing the 2004-5 R6 and R1, JUST DOUBLED! ($) 🙂
  
  Great work by the way….keep the spy vs spy cameras rolling!
  

• I think, Trying to cause a suspension revolution (right…), or just trying to be diffrent, and I think they are thinking: “why not try something new? (or old for this point) we have nothing to lose, and we might invent something good”
  

• Pretend that you are in a Yamaha brainstorming session and follow this line of thinking….
  
  Ok, so we want to get the exhaust pipes out of the windstream because they add a lot of drag. So let’s route them to the tail section, which will help aerodynamics even more by using hot, expanding gases to fill the drag inducing low pressure area at the rear of the bike. But a single shock would be in the way of the pipe and routing the pipe around the swingarm and shock will result in lots of undesirable contortions or both the pipe and swingarm, not to mention blocking cooling air flow to the shock body. OK, what if we put the pipe where the shock is and then use two smaller shocks on either side of the pipe? That gets the pipe out of the airflow along the side of the bike (which reduces drag), puts the shocks where they can get some cooling air so that they won’t be as prone to heat induced fade, allows the exiting hot exhaust gases contribute to reduced aerodynamic drag at the tail section, and makes the shocks easier to get to for adjustment. Cool, why didn’t somebody do this before?
  

• Well I can’t imagine there being any kind of weight advantage or even a ride advantage with twin rear shocks. Anything those 2 shocks can do, 1 could do. My theory then is that maybe the rear tire is designed to pivot along the longitude length of the bike. Imagine the bike being banked in a turn, and the rear wheel is a bit more upright than the bike, this would allow more power to be applied earlier out of the turn. Maybe that linkage somehow links the front to the rear so that when the front wheel turns to the right the top of the rear tire is pushed out, and vice-versa. All these new MotoGP designs are so cool though. New engine philosphies. It’s great. Only a matter of time before it all trickles down!
  

• It looks to me as that Yamaha is experimenting with active suspension control, using linear transducers to feed information to a (brain) to control the shocks hydraulics and thus the suspension.
  

• Yamaha is trying to lighten the frame and swingarm. The lighter the swingarm the easier it is for the tire to stay on the ground. It doesn’t look like the shock is attached to the rod.
  I think they have given the upper shock mount an adjustable mounting point. The rod may be there to limit frame flex, or maybe to measure it. I still wonder why they have not tried 2wd.
  

• I have no idea. Perhaps the swingarm has flex built in and this is an attempt to control it precisely from each side. Making the chassis completely tuneable for every circuit, left and right handers.
  
  Or, maybe it’s just an effort to make life easier for Ohlins. If they have 2 shocks doing the work of one, we can conclude that they’ll run cooler and therefore more reliably.
  
  Honestly, I think it’s just a space issue. That new exhaust is sweeping right up the middle, leaving no room for a standard single shock. That’s really the best of my three guesses.
  

• Some random thoughts on the Yammaha two shock design testing:
  
  1. Makes for a nice clean underseat exhaust system without excessive bends around shocks, etc.
  
  2. Makes for half the work for each shock, therefore they can be lighter in design, and possibly increase resistance to overheating during hard use.
  
  3. More rigid chassis design for less weight (as a package), since the swing-arm rear can now be a lighter weight with the two shocks providing increased resistance to flex due to their mounting points. (ever play with legos? a two shock design is inherently more stable)
  

• Though small, each increment of gain is fairly important at this level of racing. The first advantages probably accrue from the swing-arm. Its mass is now lower overall. The stiffening triangulation is below the axle line rather than above.
  There is no longer a need for an apparatus on the swing arm assembly to harness the large single shock as now those forces are handled by the twoforks. Those forces are now transferred directly into the main spars no longer requiring a centrally located frame apparatus to handle the shock/spring force. The absence of shock/spring/framepiece frees up area for an easy exhaust path. The smaller springs behave differently than one large one – response is likely to be more sensitive – less inertia
  Shocks similarly, plus more relative area for valving Overall, lower CG, less moving weight, less overall weight, better shock spring control/tuning, freer path for exhaust – Looks good to me in theory – lets see how it works
  

• it looks to me like they are trying to control sideways chassis flex, or to damp it some way. the way the twin rear shocks are not exactly vertical suggests that they have some effect on swingarm movement side to side,
  which could help control bump absorption and reactions when the bike is heeled over. that’s my guess anyway.
  

• It appears that the twin shocks are an attempt to maximize space without messing up the aerodynamic profile of the bike. They can tuck the shocks into the bodywork and then route the exhaust right up the center thus necessitating fewer bends in the exhaust pipe, which makes more power. Those telescoping rods in the picture are most likely accellerometers or some similar measuring device. They can measure everything from frame flex, to rear wheel travel with the things.
  

• Yamaha is measuring deflection (flex) from right to left on the rear and also to the front. That is not shock linkage but measuring devices.
  

• I am typing from Brasil, and I am a racing pilot here in South America. I own a CBR-600 and the biggest problem of my bike is the rear shocks.
  I think yamaha and ohlins are starting a new idea for hi performance motorcycles, and that´s very good because the most problem in that kind of racing bikes is the shocks starts to loose the capacity after 10 fast laps, and maybe two of them in the rear can work better than one! Last year the biggest problem of 4t bikes, specilly honda, was the tires, is very difficult to make a soft compound capable to make one entire race…..
  Maybe is a good start for yamaha, if this configuration of the rear “could improve traction and tire life” yamaha could use soft tires than honda at races, and that is more stability, more traction, maybe the most important gain in the race for seconds!!!!!!!
  Hey, and I am sending a picture of racing here in Brasil!
  

• It appears that the tops of the shocks are mounted to a common, connected bar running across the chassis. Question: Does the shock mount pivot?
  

• My guess???
  
  It looks to me like a twin shock full floater similar to the old Suzuki full floater but employing two shocks. A linkage compresses the shock from the top and the swing arm compresses it from the bottom. Why duel shocks? I believe they are evaluating weight and packaging options. Those shocks look small and maybe there is a weight savings with the swing arm, small shocks, small linkage, no super structure in the frame for the upper shock mount.
  
  The big advantage would be air box or in this case exhaust routing. I think your right on the shock looking thing on the top of the frame, I think it is to measure frame flex. At first I thought maybe it was hooked to the top linkage on the shocks and transferred the frame flex into the shock. That red rod hooking the sub frame to the swing arm is most likely a shock clock
  type of devise for information gathering.
  
  Also noteworthy is the rear caliper hanger mounted off the back of the swing arm. And, is that a vented rear rotor?
  
  Is this bike a V-twin?
  
  I have designed may clean sheet suspensions for the fun of it. My favorite is one that employs two leaf springs (one for the front one for the rear) that mount under the engine and have adjustable progressives via adjustable ramps the leaf spring compresses over. The front suspension is also a swing arm type connected via a pull rod to the leaf spring. Advantages being
  light weight, weight placement, packaging, adjustability, tunable antidive in front, tunable geometry. I can send a drawing some time if you like.
  
  Thanks, that was fun.
  

• Way out there: Different damping for upright and leaned over with microprocessor control? Not so way out there: Separating high and low speed damping into two shocks for greater precision?
  

• If the frame is flexing that much to have a linkage of any type, I would not be riding it.!!
  
  I think the piston/linkage is a steering stabilizer, mounted at a convenient spot for on the fly adjustability. ( Photo “1” and “3” ) The Black colored rod/piston linkage seems to be mounted to the “top” of a lever-arm that *might* have different ratios.
  I notice the welded part of the frame and the bolt and nut thru the linkage to the frame tabs, or to the lever tabs
  
  The Red linkage/rod/pistons mounted to the swing arm might indicate a form of measurement on the swing arm rotation as compared to the fixed frame.. Years ago a rod with rubber washers was used by some tuner to find the “sweet-spot” for the correct feel of the swing arm and tire contact with the road.
  
  I did notice that the shocks are offset from the center of the swing arm looking forward ) towards the sides of the bike.
  This seems to be done for space for the exhaust. Maybe the Red linkage/rod/pistons are measuring any “twist” that might occur between the “right” side and “left” side of the swing arm to frame, or differences in the shock rates between “right” and “left”.
  
  Great photos, and I am looking forward to the “answer
  

• If that rod isn’t equipped with a transducer of some kind it isn’t recording anything. We can’t see the front so that is unknown. Could be that they are making adjustments to it to tune the chassis.
  

• The rod tying the rear of the frame to the steering head is probably a damping rod which eliminates/reduces forces transmitted to the frame from the rear shocks upper mounts – which can cause chatter (the rapid oscillation of the wheels typically seen under heavy braking which reduces tyre life) in a normal setup.
  
  BR>
  I’ve taken this info from todays issue of the UK weekly paper Motorcycle News (Feb 26th edition) which has a more detailed explanation of the damping rods AND the setup around the rear shocks. Without a diagram it’s a little hard to explain, but their text says:
  
  BR>
  “When the swingarm moves upwards, it pushes the shocks lower end at the same time as the ride height adjuster rod which connects to the shocks top via a rocker arm. The shock is compressed from both ends. Any forces transmitted to the frame from the shock’s upper mount are minimised by the damper rod to the headstock. “Hope this is useful…
  

• OOOH!! I’d sell my friend’s kids to be able to scratch and sniff at all that mechanical beauty! What are they up to? From what I can see of the pictures, and that’s not saying much…, all of those mounting points are fixed. Sure, they may look coupled at first glance but, in my “obscure picture”‘d opinion, those “preload adjustable longitudinal frame tensioners” look like they might do just that! Newly patented “AFDBx Frame” Adjustable Flex Delta Box frame… To me they look like fancy internally preloaded turnbuckles linking the highly stressed upper shock mount frame area to the steering head. One frame, many venues, many riders, many smiles… Good work, great site!
  

• The rods on the Yamaha GP bike appear to be small shock absorbers to control the oscillation of the designed flex the engineers built into the frame.
  

• I’m not an engineer, and just an average rider. But it seems they are trying to isolate, the stress variables that a tire has to endure.
  
  
  With the flex of a frame, the movement of a tire under stress(cornering,acceleration) the variables of wear must be quite exstensive with all the different movements between the bike/frame/ and tire envolved.
  
  
  Maybe the twin shock reduces c e r t a i n aspects of frame flex, and allows a better “mapping” of tire wear = grip = wear.and where they start and end, during different circumstances.ie; entering, exiting corners
  
  
  Trying to gain as much accurate information as possible in any senario is expedited by removing or understanding what data is applicable, to which circumstance at what time
  The more accurate the information the better the results. I tried!
  

• It’s nice to see a manufacturer (besides Honda) try something new and unique. MotoGP is supposed to be a racing series where manufacturers can invent and test new ideas that will forge new frontiers in motorcycling. But so far, nothing of any real interest, aside from Honda and Proton’s V-5s, and Aprilia’s pneumatic valves, have really been very interesting. But now, Yamaha comes out with this new prototype. WOW! New fresh ideas!
  
  The twin shocks could easily be used in order to have good low speed and high speed rebound/compression/preload. One shock has to make sacrifices in order for it to work over large and small bumps, this could resolve that. The rod between the rear of the frame and the front of the frame probably doesn’t measure chassis flex, but instead controls it. Honda and other manufacturers have played with variable chassis flex ideas in the past. Maybe Yamaha wants to develop a bike that bends and twists purposely, to allow better traction and control. Also, chatter could be prevented by damping out unwanted vibrations. Chatter is a problem when stiff (read: fast) chassis setups cause the front tire to bounce on the tarmac faster than (or in different directions than) the suspension can move. I hope Yamaha succeeds with this prototype, and proves that a company do! es not need a Honda sized budget to succeed in Motorcyle racing.
  

• It looks as if Yamaha is tired of getting it’s ass handed to them and is focused on Rossi & Hayden being 2nd & 3rd on the podium!
  

• You say “it almost appears like the shocks employ linkage at their top mounting point,” and ask for our thoughts …. You only show one side of the bike, but If the “linkage” is common to both top shock mounts, and those linkages are attached to a common rod/tube running across the bike, then another “link” (arm, actually) on that tube connected via screw-thread to the frame would allow simple and quick adjustments to ride height without concern for ensuring both sides/shocks remained equal length.
  

• Truth revealed: the little red thingies are the real shocks while the Ohlins are just to confuse the competition.
  

• The depicted linkage looks to be ‘ride height’ adjustment hardware. Dual rear shocks permit an opening for a seat mounted exhaust and mark the return of chassis tuning to Yamaha Motor Corporation. It’s gratifying to see this leading proponent of ‘monoshock’ technology has finally determined, after 30 + years of effort, that Norton’s original ‘featherbed’ chassis design is a valid technology base! Where did I put my old Koni and/or Bilstein shocks?
  

• The “rods” running up either side of the frame on the YZR M1 prototype are almost certainly dampers, not sensors. This is the next evolution of the controlled flex frame development started by Honda and now pursued by all major manufacturers. The objective is of course to provide lateral “suspension” so accomodate sideways forces imparted to the chassis while leaned over in curves. This has been accomplished by reducing the lateral stiffness of the chassis while preserving (or even increasing in some examples like Yamaha) torsional and simple longitudinal beam bending stiffness. The drawback of these solutions is that the resulting lateral defection of the chassis is undamped or at least damped only by the dissipation in the frame metal itself. It is difficult to fabricate a frame with anisotropic material characteristics. Anisotropic performance characteristics can be obtained by constraining the forces coming in from different directions to be carried by beams of varying cross sections (current state of the art) but varying the material characteristics would require advanced composite materials not likely to ever be cost effective on a production bike. Yamaha seems to have chosen instead to employ an “evolutionary” approach of fitting hydraulic dampers acting on the lateral flex motion to accomplish the needed damping. This feature may well be on a production bike within the next few years. A engineered composite frame with anisotropic stiffness and damping characterisitics is technologically possible but would probably never be offered for sale at mass production prices.

  The reason for twin shocks may be to reduce the peak loading on the swingarm at the shock attachment point. The shocks are attached further away from the pivot point which lowers peak stress. This makes it easier to increase the torsional stiffness of the swingarm while maintaining or reducing weight. By allowing more flex in the frame (because it is now damped by those lateral dampers), Yamaha can increase the lateral stiffness of the swingarm but you need cross bracing in the crossover front part of the swingarm to do this. Similarly to increase the torsionsal stiffness of the arm, you need to add depth to the crossover portion. Both of these goals are easier to achieve with twin shocks compared to a single shock. Twin shocks with linkage at the top opens up the area under the crossover portion of the arm for more efficient (i.e. lighter weight) bracing to gain torsional stiffness. Less unsprung weight is the result and this will give the claimed reduced tire wear and greater traction. Improved swingarm torsional stiffness may also provide the same benefits while also improving directional stability.

  The drawbacks to this design approach are some reduction in mass centralization and possibly a slight increase in total weight from two shocks. For a production bike the twin shocks will also add some cost but this is not a concern for the race machine.

  Thats my 2 cents worth.
  

• Well I was pretty pleased when I saw those photographs! I remember reading something about ten years agao when some chap from a suspension firm said twin shocks were not inherently worse; it’s just they were not trendy and most designs of the actual shock used were ancient. Not only that, i remember the rotary Nortons that won the british superbike championship, and were so fast the big four appeared to get together to force a ban on them in racing had yep…..twin shocks.
  

• I always recognized the monoshock 1974 Yamaha YZ250 as the greatest single improvement to motorcycling, so it’s quite a surprise to see them toying with a dual shock’er. What could Yamaha have up it’s sleeve? More weight, more complexity, more things to go wrong. Baffled….
  

• i think they are on to something. if they can get more traction and better tire life they may have a chance of running with rossi on a more regular basis. yamaha has always been a leader in chassis design. we’ll have to wait and see. nice pictures!!!
  

• That twin shock set up on the Yamaha MotoGP bike is just an indication that the Yamaha boyz are up to some heavy development to get competitive with the Honda Monster RCV-211.

  Let’s face it, the Honda, coupled with Bah-leh-teen-o on its perch, is a hard combo to beat. Only other RC-employing riders were able to best him last year. Young Nicky will come up to speed and the competition just better look out.

  I have heard from reading some off-line pubs that Max Biaggi never complained about power last year, but rather chassis composure and excessive wheel spin. So, it comes with no surprise that the Yamaha development techs are looking at Frame Flex and other chassis components to improve upon last year’s almost-capable MotoGP unit.

  Honda offered street bikes with “Tuned Flex” back in 1998 on their VTR1000…the idea was to improve contact under hard cornering and I am not sure if it was ever carried over to the MotoGP bikes. It was contrary to the idea that the more rigid a frame you have the better it will handle hard bumps, under braking while mid-cornering at speed.

  Now that Max is gone, it is the perfect time to break in the new riders to a new bike. I suspect that dual shocks, couple with a “tune-flex” chassis will be two of many new ideas, or new ways to use old technology to the forefront of race-bike development.

  It is fantastic to see that the competition is not lying down. I would really enjoy a more competitive season. I got a little tired of seeing Rossi hone his Champagne bottle opening skills.
  

• I think they are:
  
  1 trying to eliminate twisting at the swing arm pivot and shock mounts
  
  
  2 they also are putting all force from the rear suspension in a parallel pattern in line with the spars in effect triangulating the swing arm to the steering head
  
  
  3 an attempt to control frame flex accurately for precise feedback to the rider
  
  
  4 all the rods from the swing arm to the frame and the rods that go from the shock mount to the forward part of the frame are measuring instruments for telemetry.I think the top shock to frame rods are for independent reading of both sides of the frame.
  
  
  5 I think each shock can be independently adjusted for desired flex effect of the frame and for a specific track
  
  6 by the design it enables them to lighten the frame significantly enough to allow twin shocks and this allows the shocks themselves to control frame flex making it easy to adjust to specific tracks and riders.
  

• Ya know a long while back there was a fellow that designed a dual back tired swing arm for parapalegics that locked in place at stops, giving the machine a small tripod. Underway both back tires leaned together and tracked just fine, the tester that wrote the article raved about how it tracked in corners.
  
  Could we be looking at the same type of arrangement here on a lesser scale of course.
  
  
  Or, with it tied to the rest of the frame and balancing out the flex from both sides instead of the twist that a short tripod experiences could be tranfered out to a bigger foot print. Thereby increasing the stability but also giving you some wallow when it is on it’s side.
  
  
  My understanding is this would be going in the absolute opposite direction that honda is going which is to isolate the torque from the tire on accelleration from the frame. Just some thoughts, I am no engineer just a machinist, but yamaha sure has spent there time on suspension, whereas everyone else of the big four is more about motor. Just ride an fzr 400 from back in the day, and I would still wager its one of the sweetest handling machines ever made.
  

• i think the top mounts for the twin rear shocks are simply ride height adjusters and not any sort of linkage assembly.
  

• Consider if Yamaha are combining the twin shock with flexing swing arms and some form of active suspension setup. The two shocks will allow feedback not just to the vertical movement of the wheel within the chassis, but also the flexing side to side movement. If flex is as important as we are now being lead to believe, this could result in a significant increase in control over the bike at extreme lean angles… just a thought from an engineer.
  

• The single-shock was originally adopted because it freed the rear sub-frame from suspension loads. All it had to support was the rider, a saddle and a taillight and so could be made much lighter. Perhaps more important was that it freed stylists to indulge their fantasies about what riders think the back of a bike should lool like.
  
  More recently, the single shock has become a design obstacle. The upper shock area is right where you would like to put an airbox, or battery, or cylinder head. The ascent of the v-motors has made things worse; now, the shock must be nestled up to a nice hot exhaust pipe. Or two, now that underseat pipes are so fashionable.
  
  Yamaha solves the space problem and avoids the old subframe problem by mounting two short shocks very near the swingarm pivot. Now the big pipe has plenty of room, the structure is compact and rigid, and the shocks are out in the breeze. Don’t look for the twins to return to dirt bikes, though.
  
  Note also that Honda solved the space problem in a different way on their GP bike, by mounting both ends of the shock on the swingarm. They said it was to increase rigidity and reduce frame parts up high, but I can’t help but think they were getting pretty desperate to find somewhere for the pipes from the rear bank of that v5 to go.
  
  Thanks for giving us Motorcycle Daily–it and advrider.com are my only _daily_ moto necessities. Besides riding, of course! Keep up the good work.
  

• I’m amazed that nobody has done this yet…
  
  By spreading the burden of rear suspension between 2 units, surely the level of adjustment must be far superior to just one…
  
  The only reason I can think of that would have initiated the original change to a rear monoshock unit is that it allowed the exhaust to be mounted higher and closer to the rear wheel, increasing ground clearance…
  
  Now that the current trend is towards a centralised exhaust – underseat or whatever – the monoshock is a problem…
  
  Just look at the fiasco that was the TL100S rotary damper…
  
  Then you have the single sided swingarm, primarily for the easy replacement of rear wheels under race conditions, it complicates the routing of an underseat exhaust system…
  
  The twin shock system has eased the routing of the exhaust and undoubtedly spreads the sprung weight across both units…
  
  The claims of improved traction and less chatter would seem to me to be obvious bonuses of this setup…
  
  More inbuilt redundancy with 2 units sharing the load…
  
  The whole thing just smacks of such obviousness, that it’s quite amazing it hasn’t been done before…
  
  It just shows that no matter how far we’ve come with bike technology, we still haven’t come far enough…
  
  I’d put money on it showing results…
  

• Your right on the rods being to measure movement, they are linear movement transducers. My guess as to what their up to; first the 2 shocks,, first notice were they are.. on the outside,, as opposed to inboard,,why? motor placement,, wouldn’t removing the inboard mono shock system out of the way allow more freedom in rearward engine placement and also swing arm lengths? If they are messing with flexible frame systems this would also allow for more “flexible” structures than would a single point loaded sub frame, its tough to control axial twist and deformation at a center point without massive structures, the loads are placed at far ends of the center and thus have a large amount of mechanical advantage, moving the control pieces (shocks, springs) to the load allows for not only smaller (lighter) units to be used, but also a possibly faster acting suspension. I noticed the one transducer looks as if it’s run to the streering head to just about the top load point of the rear, Id say they were measuring total flex, probably playing with different materials in an effort to try and take up some of the movements that may otherwise be dealt with by the tire (take the force up in the head, save the meat) I would venture a guess that there are at least 2 more sensors across the chassis , over or under the motor, and maybe across the rear section to measure twist. I think the big thing they are looking for is motor placement (more drive off the rear) less tire spin, better life, take braking weight off the front, soften up the head, less tire wear on the front. Just my speculations.
  

• The twin shock set up is no big deal. It just frees up a large amount of space to route the exhaust. Twin shocks will allow for more piston surface area. This will allow for easier/wider range of tuning. The rod you refer to looks to be a stain gauge/linear travel sensor though I cannot see any wires from it. I am fairly certain of what it is because they will need to know these measurements with the unsupported portion of the frame bending all over the place (intentional or not). I am sure you see that the tower that the upper shock linkage mounts to has nothing to keep it from bending for/aft. I can’t help but wonder why they did this. Yes it could be another tuning option but one that requires modifying the frame. Or maybe they are thinking of changing the diameter of the rod that will replace the stain gauge to suit their goals. Interesting none the less.
  

• Yamaha is the most progressive thinking motor corporation on the planet. They are not afraid to cut new paths, or take a proven design and perfect it, because it obviously wasn’t perfected if Yamaha is using it now.
  

• In regards to the suspension on the new Yamaha M1, what is that long narrow red hydraulic looking thing attached to the rear swing arm? In the past, I’ve noticed similar looking devices on the front suspension of GP and WSB race bikes. Is it by any chance a measuring device, or is it really a functioning part of the suspension? Just curious.
  
  
  What do I think about the whole thing? Well, as an Engineering student and an avid motorcycle enthusiast, I love to see motorcycle manufacturers experimenting with new ideas in order to push the bounderies of performance to the next level. Whether or not this design is advantageous is yet to be seen.
  
  
  Bring on race season!
  

• I think Yamaha is trying to increase their profits again this year by showing that they can compete in MotoGP. So far, the future is bright for the M1. Can I get a free subscription to MotorcycleDaily.com now 🙂
  

• My thinking is that Yamaha is using a system like they use on the front & rear of an IRL car. That is they are using a piveting tortion bar that would take the flex of one side and load the other side. The IRL cars use this to control their roil center. You always hear then talk about sway bars and the weight jackers. This is how they do it. Take a close look at the front suspension on an IRL car and you will see the same type of bar running from their twin shocks through a pivet where the travel sensor is then back to the tortion bar. We just can’t see this on the Yamaha becouse it is hiden by the body work.I could go more into flex and rool centers but that would take too much time and space for just a theory on what Yamaha is doing. I would interested in just how close I am or how far off base I was.
  

• In the photos of the Yamaha YZR-M1 prototype it look like they are employing the similar technology that is used be some of the full suspension bicycles. What I feel they are try to achieve is the same effects that BMW is getting with the swing are on the R1100 bikes. Several of the full suspension bicycles had used a cam action frame to control the amount of rise and fall when power or braking is applied.
  
  The rod tying the rear of the frame to the steering head, on each side of the bike is an additional damper to control the rise, or dampen frame motion under heavy acceleration.
  
  Well that’s my read on your photos
  

• I’d bet the underseat exhaust routing necessary to maximize cornering clearance has caused inconsistent damping in the single shock design and that Yamaha reckons they can ameliorate that problem by using double the shocks.
  

• 1. A single shock with linkage is Heavy.
  
  2. A single shock with linkage makes the wheel base longer.
  
  3. A single shock with linkage is not optimally located for proper mass centralization.
  
  1. A twin shock setup can allow the shocks to specialize. 1 for damping 1 for rebound.
  
  2. A twin shock swing arm can be lighter because of where loads are concentrated.
  
  3. You can do interesting things with spring rate with two springs to play with.
  
  I have no idea what the horizontal rod is for.
  

• You’re right about Yamaha measuring chassis flex ! I haven’t seen anything with so much diagnostic equipment attached to it since the time I slid past two telephone poles on my buttocks !!
  

• The dual shocks could have a few design benefits over traditional single shock configurations.
  
  
  1. Two smaller shocks allow for different mounting and locating options in an area where space is critical due to optimal engine exhaust design needs. An exhaust header snaking around the outside of a swingarm can rob power as opposed to this central routing.
  
  2. Two shocks allow for twice as many rebound and compressions dampening circuits and thus more adjustability. One of the shocks may be designed to control low speed dampening and the other high speed.
  
  Without the ability to see the complete upper linkage it is difficult comment on its design objective.
  
  
  The telescoping mechanisms appear to be temporarily mounted for frame flex telemetry.
  
  
  Your site continues to be one of my favorite. Keep up the good work.
  

• Thanks for the great pics of Yamaha’s prototype.
  
  It’s obvious to me that this bike is a VERY elaborate test mule. They appear to be looking to measure frame and swingarm flex/twist at every location possible. I don’t believe that is a linkage at the top shock mount though. At least not in the rising rate capacity of a “linkage”. It looks to me as though it is used to adjust ride height. This would be a good method of insuring that both shocks are set at precisely the same length throughout the setting range. That would be accomplished by the “linkages”, or as I’d call them “yokes” at the top of each shock being attached via a common tube that runs across the frame and pivots on the frame bolt you see at the top portion of the triangular frame casting. It would be an easy way of making quick and minute ride height adjustments. Maybe…huh? Who really knows what lurks in the minds of those guys. No matter how you cut it, that is on trick piece of equipment.
  
  It’s interesting that as the four strokes evolve in their development everybody, except for Aprillia and Suzuki to this point anyway, seems to want to take a shot at getting the exhaust can out of the air stream. Personally I hope that they don’t all find it to be that beneficial. Otherwise all these “new” bikes will end up looking very similar in their outward appearance. Much the same as “the old bikes” (the 500’s) did. I can certainly see where a big tube hanging out in the wind blast at 200 mph would create some drag…maybe A LOT OF DRAG but none the less it would be nice to see the bikes retain some individuality other than in the arrangement and number of cylinders behind the fairings.
  

• My take on the proto Yamaha is this, twin shocks will do the same amount of work as one so each one will develop
  half of the heat. This means more consistent oil temps and damping
  performance over race distance. This may help tire life.
  
  The linkage at the top is the same setup the Ducati uses. The bottom of the
  shock is mounted to the frame, the top works the linkage, the other side of
  the linkage goes to an adjustable pushrod (seen in the attached pic)
  connects to the swingarm. The only benefit is packaging as far as I can
  tell.
  
  The twin struts I think are an attempt at frame twist damping. As the frame
  twists, one link will get longer and the other would get shorter. The strut
  on the left side seems to have a displacement sensor on it (also seen in the
  attched pic). This would be used to evaluate damping performance. The
  amount of travel will be under 2 millimeters so the damping element would
  most likely be a preloaded rubber disc so there is no lag in damping
  performance. Very simple system, Not a bad idea at all. This on I would
  expect to see carry over.
  

• The twin shocks could allow the tuning of each shock for a different handling régime; i.e. one shock for exiting corners under acceleration then other for mid corner handling. Each shock, spring and linkage could be tuned separately to give different sum total suspension. Finer control would be possible than wih one shock, spring, linkage setup.
  
  The unusual mechanism from the frame to head may be a very short stroke damper or damper spring combination. These could be used to tune the lateral flex of the frame. These could be piezoelectric dampers similar to those used in skis in recent years. I think this because I can not see any electrical wiring (say for a transducer) and they are very robust for a transducer. Secondly, Yamaha professes that frame flex is being studied with this machine.
  
  That my story and I am sticking with it, :^)
  

• I would like to speculate about the “old fashioned” twin shocks.
  
  First, the obvious answer is they did this do make room for the trendy central exhaust routed out the tail section, aerodynamics are superior w/o tail pipes in the breeze.
  
  Then the long red sliders are probably LVPTs (linear variable potentiometer transmitters) for data collection on suspension travel, rates and dwell.
  
  I would suspect the black object adjacent to the suspension is unrelated, maybe a dampener/springunit or master cylinder?
  

• I do not believe these shocks have any linkage. The top mount piece looks to me like a simple forging.
  
  Notice that there are position measurement devices on both sides of the swingarm. Also, it appears to me that there are two shocks in one photo, and one shock in the other. It would appear they are trying to see if they can control swing-arm flex with two shocks.
  
  
  Similarly the two rods leading up to the stearing head are clearly measuring frame flex, again on both sides. They are wondering if two shocks can help control frame flex. Curiously, these rods change in color from black to unfinished aluminum from one photo to the next. Perhaps they found their first attempt did not have sufficient measurement sensitivity. Note the airbox was formed to let these rods through, these rods were designed in on the CAD terminals, not added on later.
  
  
  The center-up exhaust makes routing the exhaust pipes a complete pain, esp. with these new 2 1/2″ exhaust pipes. They certainly would not use the precious mid-bike space on something with such a low density without a good reason. Clearly they believe the center-up exhaust aids aerodynamics by filling in the vacuum behind the bike, and doing it completely symetrically both vertically and horizontally. They may also hope to help control drafting with this.
  
  The lower tie rods for the rear sub frame take a rather unusual path, having to squeeze in between the exhaust and the shocks and meet the lower frame cross-brace instead of the more common position on the frame itself. Another concession to the placement of the exhaust and the shocks. This substantially lowers the rear subframe resistence to flex, meaning either they are accepting more flex in the sub frame, or they’re prepared to pay a weight penalty there too for dual shocks.
  
  
  This looks to me like exactly what they represent it as: a data collection bike for new ideas. They are getting very serious about finding out what Honda is talking about with their “controlled frame flex” statements. They must be very jealous of Rossi’s drives out of corners. It would be interesting to see a picture of the steering head – an obvious question is if they are somehow prepared to alter the flex characteristics of the main frame tubes. The swingarm, they can just build a few different ones and measure what happens both in flex and in track time.
  
  Too bad the best use they can find for Abe is collecting data. I had hopes for him at one time, but it appears he was a one-race wonder.
  
  Free subscription? That’s the best you can come up with? Even SW airlines gives peanuts and cokes. . .
  

• interesting prototype..
  
  there could be a whole bunch of reasons for the twin shocks..the ones i can think off.
  
  1) create space of routing the exhaust
  
  2) remove solid shock mount to the chasis with a softer linakge and
  reduce chatter etc.. just like the unit-pro from honda (and ducati)
  
  3) also create more space for a lower tank, etc
  
  
  4) more importantly with chasis flex etc the twin shock can provide important damping for the swingarm and pivot area flex…. they seem to have two data logging potentiometers.. one on each side of the swingarm.. but located at slightly different positions and these could be measure swingarm/chasis flex.
  
  also the rods typing the steering head to the rear of the frame seem to be damping rod and not just to measure chasis flex.
  
  all this coming from yamaha.. who have been know historically to make the stiffest frames is interesting
  

• Yamaha must have dynamic analytical models of motorcycles for design work.
  With these models they can compare design changes with existing designs to
  look for improvement in weight and stiffness. The challenges with
  analytical designs are that, while they are very accurate for comparative
  purposes to other analytical designs, there is error in the correlation to
  real world components. Weight can be measured on a scale and compared to
  the model for evaluation of model accuracy, a fudge-factor is added, and
  then every subsequent model is accurate through that fudge factor. The same
  can be done with other mechanical properties such as stiffness. But many
  test rigs only allow static analysis, and with dynamic analysis there is
  always error in frequency and amplitude of inputs compared to the racetrack.
  In addition, errors pile up when putting together systems. Some component
  stiffness’ add in series, some parallel. Force transfer through bearings
  and bushings are unknowns and properties change with temperature.
  
  Ultimately, Yamaha may simply be trying to validate their design
  techniques through measurements on the racetrack. This allows them greater
  accuracy for future design work. If they know exactly, for example, the
  dynamic response of the chassis through measurements, they can better
  optimize the design of the springs and shocks for placement and rates.
  

• the rods going to the steering head and the twin shocks may be a countersteering setup to improve turnin in corners
  

• I believe that Yamaha is trying to allow the rear tire to remain in better contact via a more flexible swingarm supported by the twin shocks that will dampen and control flex . This might reduce the amount of tire slip and allow earlier throttle application.
  

• By moving the linkage off the bottom of the shock it would appear that Yamaha is taking unsuspended weight of the swingarm and moving it elsewhere. But they could be trying move the traditional stress pull of the linkage to the frame and redistributing it to a more neutral location.
  
  The damper that is on the side of the frame would be for controlling chassis flex when the bike is leaned over in a corner and hits bumps in the track. Instead of having undamped chassis flex Yamaha is trying to have damped chassis flex.
  

• I strongly suspect that the designers have taken a look at some of the mountain (off road) bicycle rear suspension setups as per linkage and shock placement. Although Mt. bikes use only one rear shock. I also side with your thought that the rod (rear frame to steering head) is to get a measure of frame flex. It looks like it has a moveable collar on
  the rod so that measurement can easily be taken. I know that this measure can be had – along with a lot of other parameters, on a fully instrumented bike, but that would add to the weight and possibly change handling to a very small degree. This rod is a great ‘keep it simple’ approach to obtaining that data. I hope I won!
  

• I am not to sure what to think. The idea behind the design sounds good, in theory. We will just have to wait and see how the suspension works. They look really cool though. Great website.
  

• This is wild!!!!! It’s just amazing how we go from 2 strokes are the bomb and then the 4 strokes are just smokin. Not having a mechanical engineering degree, but having riding motoX for 15+ years as a novice/intermediate. I could see where this may help with all the HP that the 4 strokes are making now. Have a good one and keep up the good work on the website.
  

• Different is not necessarily better and the Japanese hate to copy cat their competitors, which drives them to try different concepts. However, I believe that there is merit to this approach for three reason:
  1. having two links for the shocks means less stress on the swing arm; 2. it is an opportunity to learn and discover things that you may not have thought about or even contemplated (considering that the frame is also
  different); 3. I have to believe that the people at Ohlin know what they are doing
  
  Thanks for the interesting information and coverage at MotorcycleDaily.
  

• Your right on the rods being to measure movement, they are linear movement transducers. My guess as to what their up to; first the 2 shocks,, first notice were they are.. on the outside,, as opposed to inboard,,why? motor placement,, wouldn’t removing the inboard mono shock system out of the way allow more freedom in rearward engine placement and also swing arm lengths? If they are messing with flexible frame systems this would also allow for more “flexible” structures than would a single point loaded sub frame, its tough to control axial twist and deformation at a center point without massive structures, the loads are placed at far ends of the center and thus have a large amount of mechanical advantage, moving the control pieces (shocks, springs) to the load allows for not only smaller (lighter) units to be used, but also a possibly faster acting suspension. I noticed the one transducer looks as if it’s run to the streering head to just about the top load point of the rear, Id say they were measuring total flex, probably playing with different materials in an effort to try and take up some of the movements that may otherwise be dealt with by the tire (take the force up in the head, save the meat) I would venture a guess that there are at least 2 more sensors across the chassis , over or under the motor, and maybe across the rear section to measure twist. I think the big thing they are looking for is motor placement (more drive off the rear) less tire spin, better life, take braking weight off the front, soften up the head, less tire wear on the front. Just my speculations.
  

• The dual shocks could have a few design benefits over traditional single shock configurations.
  
  
  1. Two smaller shocks allow for different mounting and locating options in an area where space is critical due to optimal engine exhaust design needs. An exhaust header snaking around the outside of a swingarm can rob power as opposed to this central routing.
  
  2. Two shocks allow for twice as many rebound and compressions dampening circuits and thus more adjustability. One of the shocks may be designed to control low speed dampening and the other high speed.
  
  
  Without the ability to see the complete upper linkage it is difficult comment on its design objective.
  
  The telescoping mechanisms appear to be temporarily mounted for frame flex telemetry.
  
  Your site continues to be one of my favorite. Keep up the good work.
  

• Sent you a theory last week on possible engineering reasons to go with this design. After reflecting a bit, and considering that most things are
  driven by marketing and not engineering, it could be that since Yamaha owns Ohlins, the engineers were just given a mandate from marketing to come up with a
  design the “shows off” the pretty and pricey Ohlins shocks, instead of hiding them in the bowels of the bike.
  

• Here’s the low down on Yamaha’s new prototype rear suspension. Its a side motion system. When a bike is leaned over past 45 degrees the rear suspension doesn’t function well in terms of absorbing bumps. The rear suspension has to move progressively further to absorb the same size bump as the lean angle increases. There is a trade-off between full acceleration compression and corner compliance. It needs to be stiff for power delivery and soft at full lean angle.
  The two individual shock absorbers are connected to two separate swingarms that are joined near the front pivot point (but behind it) with a sway type bar, look at where the pipe goes, right through the main central part of the swingarm. It operates by allowing the rear wheel to twist about the fore/aft axis with the contact patch of the tire moving in a lateral direction relative to the bike when it is on its side. Look at the two red linear transducers on each side of the swingarm, they are measuring the twist or the relative motion between each swingarm. Better pictures of this part on www.motograndprix.com.
  The 16.5 inch rims with the high side walls also allow for a degree of side motion of the rear contact patch of the tire. For instance 50% of the rear suspension motion is a F1 car is in the tires.
  Side motion suspension is usually taken up by the flex in the frame, however frames have no active dampening, that’s why they shack and highside, with two shock absorbers on the swingarm this motion can be damped out. By allowing the swingarm to twist the frame can be made significantly stiffer (hence the frame flex transducers) thereby actively controlling and allowing for infinite adjustability for all types of tracks. By the way ever wondered why front forks will never be replaced by front swing arms? The front forks also have side motion suspension, the degree of side motion is controlled by the stiffness of the front axle.

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