The Kneeslider

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Monocoque Motorcycle Chassis Possibilities

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Ev-0 rr electric motorcycle with monocoque chassisOur story the other day about the Ev-0-rr electric motorcycle designed by Mark Wells, mentions the composite monocoque chassis. One of the comments asks:

This implies those may not be fairings, but are in fact the chassis. Any confirmation on this? What prevents a ICE motorcycle from doing the same? I know there are perimeter frames, so it doesn’t seem impossible.

Mark Wells, was kind enough to leave a lengthy comment in which he says:

The carbon-fibre monocoque chassis that the Ev0-rr will run is an evolution of the planned Lotus superbike, which was seriously considered by the Norfolk firm in the late 1990s, designed by legendary racer and engineer Peter Williams. The bodywork for the Williams-designed motorcycle is made from two parts of carbon fibre, which clamp together around the engine. Once they are bolted together they form a stiff shell, providing all the rigidity the motorcycle needs. Based around an eggshell design, it is split vertically down the middle with an aluminium section to hang the electric motors and batteries from.

Think about the possibilities of using this method of construction. Although we are used to seeing frames providing the strength in motorcycles, sometimes in conjunction with the engine itself for mounting various pieces, the automotive world has long used the monocoque chassis to great advantage. Now 2 wheelers, instead of using fairings that simply cover the sometimes untidy mechanical components, can use them to serve both exterior design functions and as chassis, too.

However, with different components to work with, electric motorcycles are under less constraint in the design process and sometimes, designers try to emphasize the difference. What happens, though, is traditional motorcyclists are less enthusiastic and sometimes put off. As Mark says:

We really feel the trick with zero emissions vehicles, at this stage in their development, is to give motorcyclists (and petrol heads in general) what they know and more importantly love. This is why the illustrations we have made for the EV-0RR are very ‘MotoGP’ in proportion and stance.

In a way, by designing an alternative power motorcycle in such a manner that design doesn’t become an issue itself, attention can return to the actual powertrain and whether or not it works as intended, winning converts, one motorcyclist at a time.

Whether the monocoque chassis becomes more common in motorcycle design will depend on other factors beyond function, cost will be a big issue, ease of working with the material and the different knowledge necessary to form a strong and safe chassis among others. All will come in time, but efforts like the Ev-0 rr show us it’s possible.

There will always be a strong attraction to exposed metal and mechanical function but this monocoque composite construction represents some very interesting design and engineering. I like it.

Comments

  1. The Britton had a monocoque frame, what litte frame it did have anyway. everything else bolted to the engine, swingarm, shock, front suspension, etc.. The “frame” was also bolted to the engine (as opposed to the engine being bolted to teh chassis) and basically a place for the pilot to sit and navigate the bike.

  2. What interests me the most is how the frame works, how stiff will it be? Will this monocoque composite frame be so stiff that even us average road riders will be able to feel the “chatter” as soon as it’s leaned over.
    Most likely this problem has already been solved, but then how? Was the direction of the composites “lay” changed to allow more flex or some other method. If anyone knows let me know.

  3. The bike must flex somewhere, whether it’s the frame, the engine, or the suspension. Michael Czysz came up with a trick suspension that flexes on different axes, which enables a carbon fiber frame to be used. I’m interested in how the engineers will deal with this issue.

  4. That is an interesting concept. The previous comments bring up interesting engineering challenges and as a mechanical engineer I can appreciate them. But also as some one who wrenches on his own bikes serviceability is my first thought. If the monocoque provides the structure to locate the wheels and provides the cover for all the internal parts do you have too disassemble the whole motorcycle to do simple maintenance? On an electric motorcycle small doors could be incorporated in the monocoque to allow access to the few internal parts that would need service. But if there was internal combustion power inside the monocoque there would be so many service holes in the monocoque what was left would essentially be a frame.

  5. Which rider has`nt dropped their bike or come off and had to re-paint the tank or replace the fairing..How much will a new carbon fibre shell cost to replace? And to put it on an electric bike?! The consumer expects electric vehicles to be convenient not expensive. Sure some cars have carbon fibre chassis but they cost half a million $ at least…Build a bike with a monocoque of another material say steel like cars, be sure to add impact protection like fenders and watch the weight add up, would`n t help the already poor performance..Maybe some motorcycles designers should design toys instead, like transformers or those electric buggies for old people, they`re electric also..

  6. easy Markkit….I’m sure those designers thought of tip over incidents, crashes, & overall costs just like all of us have.

    Since this is a racebike in a first of its kind TT, they weren’t concerned about those issues. This is all new, so many evolutions of this idea will unfold (great time to be alive). Brand new ideas will also be unveiled like this generation hasn’t seen. It must have been awesome to be a motorcycle fan a hundred years ago when just about everything was tried.

    You’ve seen the integrated Victory Vision tip over protection, right? If the above design gets to a consumer market, they might be able to incorporate various protective points.

  7. Again I really feel I should stress that the chaps who are behind this project are at Evo Design Solutions Ltd. It is the pure enthusiasm and determination of Rick Simpson, the project leader that is driving the project. Our brief was to create some evocative and exciting images which would get people/sponsors excited about the concept.

    I think it’s also worth pointing out, as it’s not mentioned in this article, this is a race bike which is in the process of being developed solely to compete in the TTXGP.

    Bruce, i believe the internal spine will be enough to hold the components together whilst the Shell is removed for servicing so as far as I understand access shouldn’t be a problem.

    Markkit your point is very valid for a production road bike but this is a pure race bike. As with almost all racing an ‘off’ usually signifies retirement from the race, and in fairness this is by no means the first, I believe Ducati are running a Carbon Fibre monocoque in MotoGP this year.

    “The consumer expects electric vehicles to be convenient not expensive.”

    Well yes of course, but in the same way that some people want different things from an internal combustion engine, 160bhp GSXR vs a 75 kms per litre Honda Scoopy, I believe the same will be true of EV’s.

  8. Didn’t the NR500 have a monocoque frame about 30 years ago? Kawasaki’s last 500 GP bike had something close to a monocoque chassis not too long after that. They were not considered successful chassis designs at all. And nothing has changed since then.

    The only way monocoque motorcycle chassis will ever make any sense is the day the FIM pulls its head out of, among other things, the thinking (or lack thereof) behind their archaic steamlining rules. The TTxGP rules aren’t very encouraging, either – too little room for innovation rationalized by too much FUD.

  9. Nobody,
    Monocoque motorcycle chassis’ are already in mass production. The ZX-12R and ZZR1400 both have them. What this article is discussing is where the engine is inside the frame, like a yolk in a egg. The most obvious advantage being weight reduction, no more need to go out and buy lightweight composite fairing replacements to get rid of the heavy plastics.
    The design of an attractive(read geometrically complex) would be a nightmare, i don’t want to even begin to contemplate the structural calculations or the manufacturing process if something similar went into mass production

  10. I seem to recall Armstrong built a carbon fiber “Tuning Fork” chassis for their early 250/350 racer a while ago. Subsequent models reverted to a similar design but in metal. I recall that easy of chassis repair &/or modification was the reason for the change. More a foam core twin spar than a monocoque in structure though. Kieth Turner had a slick aluminium monocoque Suzuki TR500 in the early ’70’s. Looked lovely as he passed me “many times” in the ’72 Singapore GP. Santiago Herraro rode an aluminium monocoque OSSA 250 in the GP’s in the ’70’s. How about the once seen at Daytona then disappeared “Monotrac” again in the early ’70’s. It had a magnesium monocoque frame as well as many other futuristic bits & pieces. Some of these are more of a monocoque fuel tank with the gubbins hanging on the edges. Still, proves that some of these ideas are worth being recycled.

    rafe03

  12. The best true monocoque that I can think of was the DH Mosquito fighter/bomber of ww2. When you looked at it you were seeing the balsa cored plywood frame fuselage that was the main load carrying structure. There were only a few penetrations. Windshield, man access hatch, bomb bay doors,etc to break up the elegant streamlined shape.

    rafe03

  14. I think a lot of popular definitions of “monocoque motorcycle chassis” is incorrect but somewhat understandable. The old Honda NR500 (well, some of them) had a stressed fairing – calling the ZZR/ZX frames “monocoque” is an abuse of the term, in my opinion. But that doesn’t stop journalist/marketing sorts from saying it. The term “Box frame” isn’t very sexy and, therefore, a lot harder to market to “technically savvy motorcyclists”. Otherwise, ALL frames are monocoque – after all, tubing is just stressed skin conveniently preformed for the builder.

    Said Kawasaki Z…. bikes don’t have their engines bolted to the fairings:
    http://world.honda.com/history/challenge/1979grandprix/text/07.html

    A number of Bonneville streamliners have monocoque structures – the fairing is the frame.

    An article from 1 year ago:
    http://www.motorcyclenews.com/MCN/News/newsresults/mcn/2008/march/24-30/mar2608revolutionarylotusmonocoque/?&R=EPI-99432

    Virtually ALL WWII aircraft had monocoque fuselages & wings.

    The best picture I’ve found of the NR500 stressed skin chassis is in Tony Foale’s book – can’t find the picture on the web. The mechanics in the picture do not look very happy.

    That said, I hope the subject bike works well – glad to see adventurous sorts in racing. An FFE makes a lot more sense than a steering head with such a design.

  15. The BUB Seven streamliner is also a monocoque shell/frame. The engine is supported by the skin, just like an “egg” concept. The aerodynamic shell is the frame surrounding the powertrain, rider, etc. But, I guess since the rider sits in that machine, its construction is closer to F1 rather than any other “ride-on” machines.

    But, I think what Wells shows above is much more than just a traditional monocoque bike frame, so it shouldn’t be compared to them. There are no doubt many examples of traditional monocoques, regardless of materials, going back to the dawn of motorcycling. The Morbidelli square-four race bike in riveted aluminum is one of my favorites, with it’s “aircraft” architecture. But this EVO bike is modern, and I think a great idea to showcase new technology. I’d personally like to see more of an exoskeleton along these lines that reveals some of the internals, without detracting from aerodynamics.
    -b

  16. Vespas have been using monocoque chassis since 1946. If you lay down a Vespa, the only way to repair it is by panel pulling, like a car. This can be quite expensive. With a composite monocoque, either there will have to be a “sacrificial” plastic fairing on the outside, or else chassis replacement may be the only option.

  17. I can see the disadvantages as others do here but what are the advantages ?
    the load paths on a bike are pretty well defined, a weight comparison would probably yield a heavier monocoque complete bike versus a twin spar complete bike
    One could also argue that a traditional twins spar is essentially a monocoque with the non-bearing material stripped away
    in other words we’re already there

  18. Plastic Kayaks have a rubber molding around the gunwale partly to cover the joint but also to provide a resilient bumper to protect the shiney glowing epoxt surface when coming along side. There’s also aftermarket bumpers available for most bikes that help protect the expensive bits if your pride & joy goes down the road sideways.

    rafe03

  19. There was a monocoque final degree project bike in a motorcyclist issue somewhere in the 90’s. It had an upper and lower carbon fairing, similar to this bike and looked like a cross between a naked bike and a faired bike…very interesting looking and it had an air-oil cooled Suzuki GSXR1100 engine if I remember correctly

  21. Mark Wells,

    I am an electric motorcycle enthusiast (a small niche among this readership) and highly encourage your innovative approach. The way I see it, your designs are another step in the same direction as the many concepts shown on the Kneeslider in which a major design piece centers on the notion that battery arrangement as part of the chassis is only limited by the designers’ imagination.

    In fact, I envision replaceable battery packs shaped like fairings or (like yours) a part of the support structure (as a quick swappable part). Or arranged aerodynamically to reduce frontal area (like a wind tunnel thru the center) and possibly to improve road grip. Or even movable packs that change the center of gravity to reflect riding conditions on the fly –i.e. starting low and centered at low speeds or straights and then moving to a higher center of gravity for the twisties.

  22. That is a pretty damn sweet gsxr, now i want more!
    The tank section reminds of FZR1000 EXUP custom i saw in PB mag a while back, the tank, seat and rear subframe were all replaced with a prepreg carbon fiber unit with the tank section looking very similar. The damn thing had the kitchen sink thrown at it, It was fitted with a supercharger but the weird thing was the oil cooler was mounted behind the seat in the subframe.

  23. The 250 cc Ariel Arrow & Ariel Leader motorcycles of the late 1950’s were but two of severeal designs, where a monocoque chassis was used. The latter Ariel was fully enclosed. They were succesful, but were soon swept away by the wave of inexpensive small cars.

  24. @Nobody: Tnx for the info on that! I remember that bike (I was subscribed to Sportrider and Motorciclist then) and that bike was a stunner in every way and still is and yes that is/was a real monocoque…

  25. good looking bike! i think i could see how a monocoque electric bike might be a little lighter in weight, but i really dont think a monocoque could be lighter than a twin spar or britton style ICE bike. i would think that bike-specific electric motors could be designed in the future with multiple attachment points to be used as a ‘stressed member’ like twin spar/britton style bikes, though most electric bikes will have some sort of fairing since batteries and an electric motor aren’t as ‘pleasing’ to look at as an engine.

  26. The main problem with monocoque frames are that in the case of an internal combustion engine, it’s very hard to service- you have to basically take the motorcycle apart in some cases.

    I think that for an electrical motorcycle, this problem is probably reduced because an electric powertrain does not require as much service as an ICE engine.

    Cost is another major issue. On a racing bike there’s no problem as teams can afford to buy pieces, but what about consumers? If I laid my bike down, how much would I have to pay to replace part of an entire monocoque? Are there still going to be fairing pieces on the bike that are replaceable in the event of a crash?

  27. I have to admit, that GSXR is exactly what I was talking about, and seeing the top bid makes me wish I had seen it earlier!

    Lots of good history in this thread as well!

  29. Carbon Fiber is the current state of the art for composite monocoque structures but aluminum sheet or honeycomb panels have been used successfully. The design of electric vehicles brings new challenges and opportunities. Electric motors do not require the same amount of maintenance as a gas engine. Most components such as battery packs, capacitors, and controllers can readily be housed in structural members. An electric motor is quite happy with some cooling air and adequate torque restraints. While FIM aerodynamic restrictions apply to racebikes, street bikes are free to employ more efficient fairings. Street bikes need to provide better crash protection. Race tracks don’t have trees, cars, wild animals or bridge abuttments in close proximity to the riders. Protection may come as foam filled plastic fairing sections coupled with touring bars or box sections. Restraint systems may include air bags on the bike or in clothing. Some of the protective gear uses aluminum honeycomb panels. The whole bike should be considered as a system and the monocoque as part with multiple functions. Modern cars use crush zones with geometry and material strength calculated to direct and convert forces to crumple metal. Composite materials are oriented to do the same thing and yes you will need to do your homework.

  30. Cost seems to be a huge issue for general customers. The Ev-0-rr electric motorcycle is a beautiful bike but with my 1990 GS500 I can take it all apart tweak tinker and play for hours. Usually very very cheaply. The electric moto brings a complete nother level of complexity. But it would be fun to learn.

  31. Does anybody know about my 1972 Suzuki 750cc reverse trike? It is tube framed and monocoque body in the cent. I will send photos! Thanks

  32. When racing MX in Sweden in the 70’s we often talked of how to cut weight, and decided a WELL-DESIGNED monocoque/engine unit is a good way to do that. Yes, we went so far as to imagine the engine as part of the entire system (as marine engines were, I worked in a shipyard, the hulls were the lower crankcases/oil-tanks/oil-coolers).

    I was so mad I was into pressed-steel engines!

    I still am, I still think a good design would be lighter and more reliable and much quicker and cheaper to make than a cast-alloy unit. I’d use a standard air-cooled alloy cylinder if not going water-cooled.

    I sat during the cold winters and designed an MX bike with the entire rear-end in mono, frame/air filter/tank/seat/suspension, bolted to a normal, tube front, that (in theory) saved weight, and certainly made servicing and repairs easy – just undo 5 bolts and swap!

    There has been an MX monocoque, but with a separate, normal engine. Back in the days of yor there was a competitor to the South Sweden-based Lindstrom company, in a place called Amal, up in mid-west Sweden, called Flink. The son was still racing sometimes when I started, though on a standard HVA, but I never met him – I did ask, interested in seeing the monocoque if it still existed (I think it does). Some recalled the bike. The monocoque contained the lot, including the expansion-chamber, to which the footrests were bolted. An earlier version used the internal volume of the solid footrests as PART of the expansion-chamber, but this was soon banned as they had now realised folding footrests avoided injury. With the Flink-modded HVA roadbike Guldpilen (Golden-Arrow) motor it was exceedingly light and was said to be a real go’er. I think money and lack of time stopped development.

    There is always a trade-off in design, and, of course, rust and crash-damage would be a problem for a steel monocoque MX’er, but when it comes to winning races that doesn’t matter. A good design would not be so delicate, m’thinks, it’s lightness helping here, I never seriously damaged a bike in all the years I raced, just mudguards, handlebars, levers etc, but never a totalled fork, wheels or even a twisted frame. Believe me, I TRIED. I had some lovely crashes the first years. I’d love to turn time back and give making a more modern Flink copy a go, though the weight-limit the FIM introduced would negate some of the advantage (but this limit DIDN’T actually apply to local Swedish races, only international ones!) I would also use rubber-suspension at the back, there are much improved units now available for industrial purposes. This would negate some of the high forces otherwise put into the frame in the wrong place.

    Isn’t getting old great!

  34. Just an update. There were about 5 Flink bikes racing, they were working on a ‘final’ design when the father died. The son had his time cut out keeping the company afloat and the bikes disappeared from the scene.

    I also recall the Hägglund army bike from 72-74, both versions were monoqoque with single-sided swingarms, shaft-drive, automatic gearboxes (Salisbury converters?) The original version even had a single-sided leading-link front fork. Due to various complaints about ‘you can’t build a bike like that!’ the original bike evolved into something looking more like a normal motorbike, hence the 2 types. I was to test the bike for an Australian magazine (during the effing winter – minus 20 degrees centigrade and snow up to me ar##! But try and tell that to the idiot sitting in sweltering Australian summer heat!! “But I need it for next months mag.”)

    And when I got there, halfway up the country, a long way (to all but an Aussie, where a 1,000miles is ‘just up the road’) I find a completely different bike to the one he wanted a test of.

    But it was very good. It coped with the snow and ice without problem, and I had asked for a bike without skis on it (I did have a short run with skis on another bike, but didn’t see the point, more likely to hurt yourself if you fell off). The big problem was that he rubber-belt in the transmission only lasted 100 miles in the hands of a conscript and the army wanted total reliability for 30,000 miles. The factory engineers got about 250 out of a belt, which was easily changed with a couple of simple tools in 2-3 minutes, several belts being carried in the built-in toolbox. The HVA auto that eventually got the contract was never that reliable either, and even if it was, cost a fortune to replace when it did need doing that, plus if it proved troublesome in the field nobody could fix it. The belt-drive, as noted, was easily fixed, albeit often. Which would YOU prefer, looking into the barrel of a Kalashnikov….

    The bikes was light, handled very well, rode the wheels of it around an mx-track without a thought of it being shaft-drive or not an actual mx:er. In fact, I probably would not have gone faster on my HVA 250 mx.

    The engineers told me the original bike was better….

    But all (about 12, I think) were posted out to regiments, so I never even got to see one.

    Hägglunds went bankrupt a while back, I believe. Hard times for a company only making military stuff. None of the bikes have even turned up on the market.