Reflections on the potential of human power for transportation

Saturday, March 14, 2015

Transcending the Pedicar: The EcoVia, Part 3


Let us review the human powered commuter vehicle criteria that were the requirements for the design of the EcoVia.

1.       Weather Protection

2.       Statically Stable

3.       Reasonable Cruise Speed

4.       Cargo Carrying Capacity

5.       No Wider than a Bicycle

6.       Same Height as an Auto

7.       Comfortable posture and ease of entry

8.       Two-wheel drive

9.       Car-type Wheels



The completion of the faring essentially brings the EcoVia Mk1 project to a close. In this post, I will discuss the construction of the faring and reflect on how well the design criteria were met, comparing the EcoVia to the yardstick for commuter vehicles, the Pedicar.

 


The foundation of the faring was a lozenge shaped rectangle of ½” dia. cro-mo tubing. This rectangle is orientated parallel to the ground. The front of the rectangle screwed on both sides to a framework that attached to the trike chassis. Pivoting around the axis formed by the two screws allowed the faring to tilt forward for rider access. Attached at the front of the cro-mo rectangle was a smaller vertical rectangle of 3/8” dia. cro-mo tubing. This is where the nose cone attached
The nose cone was made from EPS insulation foam, five 2” sheets glued together and formed to the correct shape. The final shape was coated with Styrocoat to form a hard-protective shell. The back surface of the nose cone was glued to a 1/16” thick sheet of polycarb and the polycarb was in turn screwed the vertical portion of the cro-mo frame.
The skeleton of the faring was made from ½”x 1/8” soft aluminum strips screwed to the cro-mo frame and pop-riveted to each other. ¼” x 1/8” aluminum strips were used between the larger strips.

 

The two sagittal strips along the top of the framework are spaced about 10” apart. With the nose cone removed, a rectangle of double-stretch fabric wrapped around the cro-mo frame tube at its bottom and the aluminum strips at the front, back and top. The fabric was sewn in place with Kevlar thread. The fabric was Spandura, which in addition to being double-stretch that could be made water repellant with a spray like ScotchGuard.

Screwed to the framework along the faring top between the fabric strips and behind the nose cone was a polycarb strip. Behind the nose cone the strip was left clear. Around the rider’s head the strip stopped to allow for a polycarb windscreen. A second polycarb strip continued behind the riders head. A third polycarb strip enclosed the back of the faring and was hinged at the top to allow opening and access to the luggage compartment. This hatch was held closed by a magnet screwed to the framework.

 

Wireless turn signals were mounted behind the front window facing forward and at the top behind the rider’s head facing backward.

 

The front turn signal is shown above.
A wireless speedometer was attached to the inside of the windscreen along with the turn-signal controls.

 


Rear view mirrors, which really didn’t work very well were bolted to the framework through the fabric.

 

 
A handle was attached to the framework just behind the nose cone to allow the vehicle to be lifted and moved around.

 


The weight of the entire vehicle was 83#. The weight of the faring, without the front mounting bracketry and rear faring support, was 16#.
 
Of course, the nagging question was how would the faring improve cruise speed of the EcoVia? In an attempt to assess that objectively, I spent two weekends doing four test rides over a 6 mile stretch of road that, except for one gradual downhill, was essentially flat. Three of the rides were without the faring to familiarize myself with riding behavior and the fourth was with the faring in place.

I must say up front that I no longer ride recumbents but instead ride an upright mountain bike. I never could go as fast on a recumbent as an upright, despite 21 years of riding an Avatar 2000.

I noted two speeds from each run. One was a speed past a traffic monitor set up to advice motorists of their speed that I encountered early in the ride. I had routine readings on an upright of between 17 and 19 mph. The second speed was the average for the entire six mile run.

Without the faring the speed past the speed monitor was 17mph and the average over the six miles was 14mph.

With the faring the corresponding speeds were 20 and 16mph respectively.

Needless to say, the speed increase with the faring was unexpectedly low, despite the faring appearing relatively streamlined.

Three reasons for the low improvement come to mind. One is the added drag from the flow under the faring, since its bottom is open. The second is that mechanical losses from all the drive components dominated the aerodynamic losses. The last is that a vehicle as high as the EcoVia has a large cross-sectional area than typical streamlined vehicles, even though its width approximates that of a bicyce.

The day I used the faring was a chilly 40deg F and the space within the faring was comfortably warmer that the outside with only my face and neck feeling the chill.

So against the original design criteria and compared to the Pedicar (below), how did the EcoVia fare?

 


1.       Weather Protection: Assuming the fabric was sprayed with ScotchGuard, only the riders head is exposed to moisture. Internally the wheels were covered with fenders. So like the Pedicar the EV provides weather protection.

2.       Statically Stable: The EV has a lean-lock to make it statically stable and the Pedicar is naturally so.

3.       Reasonable Cruise Speed: I feel the EV fall short here, at least with me riding it. The 16mph average should be closer to 20mph. The Pedicar had a 15mph cruise speed.

4.        Cargo Carrying Capacity: Currently the EV has about a 2cu.ft. cargo capacity which could easily be increased to 3cu.ft. The Pedicar easily has twice that.

5.       No Wider than a Bicycle: The EV has a width of 28” and the Pedicar 38”.

6.       Same Height as an Auto: Both the EV and the Pedicar meet this criterion.

7.       Comfortable Posture and Ease of Entry: Again both vehicles satisfy this criterion.

8.       Two-wheel Drive: Both vehicles satisfy this criterion.

9.       Car Type Wheels: The EVs wheels can be removed with one screw. They are all the same and it carries a spare. It is not clear how the one would remove the Pedicar’s wheels.

10.   Electric Assist on Hills: Attempts to add electric assist to the EV have been put on hold indefinitely because the electrical engineer assisting me had more important obligations. Two attempts to develop a motor controller were unsuccessful. Only a small fraction of the motor’s 600 Watt potential were delivered by the batteries. The Pedicar has no electric assist.

I would say the EcoVia met seven of the 10 criteria. Bumping up the cargo capacity to 4cu.ft. should be straight forward. Bringing the cruise speed up to 20mph appears to be a lot more difficult.

 Some final thoughts:

 
1.       Starting and the lean lock: The procedure for starting on a recumbent bicycle requires supporting the bike with one foot and keeping the other foot on the pedal. The pedal is thrust forward and the bike needs to be moving fast enough to maintain balance until the second foot can thrust on the pedal. With the EV starts in this fashion were usually successful. If a start failed due to lack of speed, one foot could be put down to maintain support.
 
With the addition of the faring it was difficult to get the support foot back to the ground after unsuccessful launches. The presence of structure and the narrow width of the faring inhibited getting a foot back on the ground. Several painful crashes ensued during unsuccessful launches. 
 
So successful launches with the faring required the use of the lean lock. Below, the disk brake that acted as the lean-lock for the EV.

    


When the lean lock is engaged the vehicle is like any other statically-stable tricycle. The level of static stability is therefore a function of the c.g. height, the track width and the load distribution of the wheels.

Engaging the lean lock also makes climbing slow-steep hills much easier. You don’t have to waste energy and concentration on trying to balance the vehicle at very low speeds, which is where balance is poorest.  

So for the EcoVia Mk2 I will be lowering the seat height from 24” to 20” and increasing the track from 20” to 24” to improve static stability when the lean-lock is engaged. The other improvement will be pivoting the faring at the back instead of the front to eliminate the weight and the foot interference produced by the faring-support structure around the front wheel.

Below is the EV with the seat height reduced about 4”. Compare this to the second picture in the post.

 


 
2.       Aerodynamics and the Delta Trike layout. Despite the poor performance of the faring, I am still bullish on the rear-drive delta-trike layout. The drive to the rear wheels does prevent clean streamlining of the wheels, but the overall package is very compact and that should keep the wetted surface of the faring at a minimum. The most logical addition to the faring design in a panel under the vehicle to enclose the faring. It is in this area that the rear-wheel drive and pivoting-wheel beams presents problems.
 
I do take hope in the success of the Velotilt design. While the Velotilt drives the front wheel instead of both rear wheels it is the design that is most similar to the EV.

 
 Granted, the Velotilt is much lower than the EV and the streamlining much more sophisticated, but the 6okph speeds the vehicle is capable of obtaining indicate there is hope for the EV to sustain 35kph.
3.       Future weight reductions: I feel that is should be possible to pull about 20# out of the current weight of 83# for the EV. Most of this will be in a significant simplification of the chassis.

a.        An 11 x 1 drive will replace the two-stage 7 x 3 system with it twin bottom brackets.

b.      The structure for front faring pivoting will be eliminated.

c.       The Soft-Ride-type seat suspension will be eliminated in favor of a mountain-bike shock connected to a link that holds the linkage that synchronizes the pivoting wheel beams. This will remove one large frame tube

d.      Hydraulic disk brakes will eliminate the brake synchronization linkage that allows one lever to activate both rear brakes.

e.      Tube size and gauge will be optimized and not overdesigned as is currently the case.

So I consider the EcoVia Mk1 to be a successful proof-of-concept of a two-wheel-drive tilting trike, but much must be improved in production prototype.

Hephaestus

Saturday, July 12, 2014

Graeme Obree's Beastie: The Lure of the Linear Pedal Drive




This post was inspired by Graeme Obree, two time world hour record holder on modified upright bikes who, at the age of 48 rode his Beastie streamlined prone bicycle into the record books last September. Obree was attempting to break the flying 200m sprint for human-powered vehicles which stands near 83mph. At 56.6mph, Obree came up a bit short. Nonetheless, he did break the record for a streamlined vehicle using a prone rider position, and more significantly, in my opinion, he broke the record for a vehicle using a non-circular pedaling motion.

The two pictures below show a kinematic model of the Beastie's drive mechanism and an enlargement of the resulting pedal path. The path is an elongated ellipse whose major axis is tilted slightly downward front to back.




In the pictures above the cranks rotate in a clockwise direction and the pedals move in a counter-clockwise direction around the ellipse.

Obree bested the existing record for a linear-drive and prone-posture streamliner held by Richard Byrne on Steve Ball’s Dragonfly of 54.9mph. The Dragonfly used both arms and legs moving in straight paths for propulsion. The picture below is from Human Powered Vehicles by Abbott & Wilson.


For the purposes of the following discussion, I consider linear motion to include pedals moving in a straight  line, pedals moving in large arc over a small portion of a circle, and numerous curves generated by four-bar linkages having paths that are significantly longer (in the leg-extension direction) than they are wide. These coupler curves could be egg shaped, elliptical, figure-eight shaped among others. In the case of the Beastie, the pedal path is an elongated ellipse.
When someone of a technical bent takes a close look at the bicycle for the first time, they invariably comment that there has to be a more efficient means for the body to generate mechanical power than circular pedaling. Since a runner’s feet don’t go in circles, it makes no sense that feet going in circles on a bicycle are neither natural nor efficient. More often than not, the conclusion is that feet moving in a near-linear path would be a significant improvement.
The drive mechanisms that will be discussed here fall into two broad categories, oscillating treadles and constant-torque treadles

Oscillating treadles consist of an input link permanently connected to an output crank through an intermediate link. When the output crank moves continuously, the output link moves back and forth between its extreme positions or oscillates. For a constant crank speed, the speed of the input link varies over the cycle and often comes to a complete stop at the limits of travel. By its very nature, one important characteristic of the oscillating treadle is that one cycle of the input link results in only one rotation of the output crank. Some form of gearing is usually required between the crank and the wheel. These systems work best with fixed gearing so that the vehicle motion carries the pedals through their motion-dead spots
 The crank slider (the core of every IC engine) is an oscillating treadle. The mechanism used in the Beastie was a offset-crank slider where the slider track is not lined up with the crank pivot. In addition, the pedal is located above the connecting rod. This produces a relatively horizontal-flattened ellipse located above the crank center, which accommodated the rider being located above the crank center.


Because friction associated with the slider can waste energy, a rocker link often replaces the slider for mechanism used for human power generation. The connecting rod moves through a short segment of a large arc instead of a straight path.

When used by Kirkpatrick McMillan in the mid 1800’s the crank-rocker mechanism was the first bicycle drive.

Oscar Egg, a world-hour record holder on upright bikes, used a crank rocker for a streamlined recumbent design. Notice that this is a fixed-gear system where the vehicle motion prevents the pedals from stopping at their dead spots.

And the prolific Gary Hale produces his Glider which employs a crank-rocker.

And the crank rocker is still used to propel most children’s kiddie cars.
Referring to the crank-rocker diagram again, if the pedals are located at point A, they will travel in a circle. If they are located at point B, they will travel in a large arc. If the pedals are attached to the connecting rod, at point C, they will travel through a hybrid of the circle and the arc, an elongated teardrop. These coupler curves have the advantage that the pedal continues to move at the ends of the stroke conserving some of the kinetic energy of the moving limbs. The downside of locating pedals on the connecting rod is the pedals are connected to the frame through two pivotal joints instead of one. This can result in more flexible connection (read sloppy) than a connection through only one joint.
Another oscillating treadle mechanism is a rocking slider. The slider is attached directly to the crank instead of through a connecting rod. To compensate for the transverse motion of the crank, the slider must rotate about its sliding point.
 The K drive, nicknamed because Miles Kingsbury used it on one of his streamliners, is derived from an elliptical trammel. The mechanism can produce a straight pedal path but as configured here it produced a long-thin ellipse. The pedal path produced by this configuration is very similar to that employed in the Beastie.

The other drive mechanism that will be discussed is the constant-torque treadle.

Unlike the oscillating treadle, the ratio of input lever speed to output shaft speed is constant (and as a result, so is the torque). There is a one-way clutch located in the cable drum which allows the input lever to return to the beginning of stroke without reversing the motion of the output shaft. Additional stops must be inserted to limit the input link travel. The ratio of input link motion to output shaft motion can be adjusted by changing the position that the cable attaches to the input lever. This is one big advantage of the CTT; it can incorporate a very simple means to achieve multiple gearing. Some form of return device, usually a spring, must be used to reverse the input link motion at the end of travel.

The CTT is the mechanism most often reinvented by those who would improve the design of the bicycle propulsion mechanism. It is also has been the most prevalent drive system after the rotary crank. It was used on the American Star pre-safety bicycle in the late 1800’s and you can still find numerous prototypes today. Steve Ball’s Dragonfly used a modified version of the constant-torque treadle, as did the Pedicar.




There are several reasons why a person designing a human-powered vehicle (HPV) would use a pseudo-linear pedaling motion.

1.       There is interference between the pedals and the steered wheel with circular pedaling motion.

W. D. Lydiard used a rocking-slider mechanism to reduce pedal-steered wheel interference on his entry for D. G. Wilson’s 1968 Human-powered-vehicle design competition, the Bicar. The picture is from the first edition of Bicycling Science by Witt & Wilson.

I experimented with a crank-rocker mechanism in an attempt to reduce pedal-steered wheel interference in my EcoVia commuter trike design.


I employed a two sided pedal in this design. The outboard side of the pedal holds the rocker link that supports the pedal. In this location it is spaced wide enough to clear the turning wheel. The inboard side of the pedal holds the connecting rod which is located above the wheel and includes a bend to clear the wheel. This is my interpretation of D.G. Wilson’s crank-rocker concept sketch for a recumbent bicycle.

2.       The foot and knee moving through a pseudo-linear motion take up less volume than circular pedaling
A classic use of linear motion for this reason is in the Pressodyne streamliner form the late 1970’s. The article is from the Spring 1980 issue of Human Power.

Here are a few highlights relevant to the current discussion. The pedal motion was truly linear using rollers to support the pedal arms. The stilts-version of the Pressodyne used cables that connected the pedals to one-way clutches. This was a constant-torque treadle approach but no efficient means of limiting pedal travel was provided and the pedals crashed into the stops. The three-wheeled version used a crank-slider approach which was much smoother. The smoothness was also due to the fact that there was also no freewheel in the system (fixed gear). So, when the vehicle moved the pedals moved and there was no issue with dead spots in the motion.
The shape of the Pressodyne was not far of the mark for the optimal streamliner shape. Notice the similarity with probably the epitome of streamliner design, the Varna Tempest. The tempest required a bigger nose to house the circular pedaling but had a smaller canopy.


And reducing swept volume of the leg and foot is undoubted the reason Obree employed a teardrop-pedal path in his Beastie.
3.       The linear drive is simpler that a pair of cranks, a chain and two sprockets.
The Mergamobile was a pretty simple approach as was the 1921 J-Rad. One used the different pedal locations to obtain three different gear ratios. Both design use constant-torque treadles.

4.       The linear drive is more efficient than circular pedaling motion.

The constant-torque treadle is the most popular design proposed for improving the efficiency of bicycle propulsion
.
The most publicized use of a constant-torque treadle was in the 1973 Pedicar.



Trevor Harris, a race car designer and designer of the iconoclastic Can Am Shadow produced the Harris Vertical in the mid 1970’s.

The Alenax Trans-bar bicycle was commercially produced in the 1980’s.

The Alenax was an almost a direct copy of the Svea manufactured in Sweden in the late 1890’s. Paul de Vivie, Velocio, the pioneer cyclo touriste, supposedly experimented with the Svea in his quest to find the perfect touring bicycle.
Notice both the Harris and the Alenax have adjustable cable-attach positions on their pedal levers for variable gearing and both have synchronization mechanisms to move the pedals in opposition to each other. The Harris uses a rocker linkage and the Alenax uses a cable loop.
When discussing the reinvention of the constant-torque treadle, I can’t help but hear Santayana’s quote “Those that cannot remember the past are condemned to repeat it”. In this case “know the past” is more appropriate. The following optimistic declaration that the bicycle has been greatly improved is a fun foil to discuss the shortcomings of constant-torque treadles
.

It also may be useful for the reader to review the section on Power in the following post.


Let us begin with why the constant-torque treadle appears to be more efficient than the rotary crank. Assume the rider exerts a force of F in a straight line with each leg. With a rotary crank the torque that is transferred to the wheel is F*sin(theta) where theta is the crank angle. The average torque over a cycle is 2F/Pi or .64F. So from the start, from a torque standpoint the CTT is 57% more efficient.

Unfortunately there are two factors that prevent this increase in torque from being converted to an increase in power
.
Our linear-motion bicycle salesman states that his drive develops full power from the beginning. That is not true. At the beginning of the pedal stroke, the foot is stopped but the output shaft is moving at full speed. It takes a portion of the pedal stroke for the pedals to catch up to the output shaft and during this catch-up phase no force is being produce and, as a result, no power is produced. Both the Dragonfly and the Harris Vertical incorporated cams to gear up the pedal stroke in the beginning to allow the pedal speed to more quickly match the speed of the output shaft. However the cam must be designed for a specific gear ratio. So on the Harris Vertical, the cam will only be effective for around one gear selection.

Another problem is the pedaling speeds that can be sustained with linear drives are significantly lower than those that can be sustained with a rotary crank. This is due to the kinetic-energy fluctuations of the moving limbs. With linear motion the foot stops at the pedal extremes and the kinetic energy drops to zero. With circular cranks, speeds of 300rpm have been achieved because the kinetic energy is relatively constant.  Since power moves the bike and since power is the product of torque times angular velocity, lower pedal speeds result in lower power levels.

The rider is very diplomatic when asked for his impressions riding the linear bicycle. He says it is much better than the first prototype but he doesn’t say it is better than a regular bicycle.

The linear bicycle riders comments that his leg muscles have gotten bigger riding the linear bicycle is an indication that things have become less efficient as opposed to more efficient. When Paul Dudley White, President Eisenhower’s personal physician and bike advocate, rode the Pedicar, he also noticed that it put more strain on the thigh muscles.

One factor that is inconsequential for light-weight vehicles like bicycles but becomes a problem for heavier commuter vehicles is that with the CTT drive, the vehicle cannot be rolled backward. The one-way clutches lock up going backward causing the input levers to jam against the motion stops. This is the reason the Pedicar incorporated a reverse gear at the cost of a significant increase in complexity of the transmission.
There appears to be a means of accelerating the foot at the beginning of the pedal stroke that remains effective throughout an adjustable gear range. When cams were used above, they were inserted in series with the drive cable. I advocate using springs in parallel with the drive cable.

Assume a synchronizing linkage is used to connect the pedals and move them in opposition.  Springs are located so each pedal compresses the spring as the pedal is pushed forward. The springs exert no force at the beginning of the stroke and exert maximum force at the ends of the stroke. Assume the force at the end of the stroke is 2*F.

The combination of the synchronizer mechanism and the springs results in the force vs. pedal position shown in the first graph. With no external load, the zero-force position for the pedals will be at midstroke. From the beginning of the stroke to midstroke, the springs act to move the pedal forward, accelerating the foot. From midstroke to end of stroke, the springs resist forward motion and add to the force required to propel the vehicle. If the average force required to drive the vehicle is equal to F, then each pedal sees a force vs. displacement curve shown in the second graph. The pedal encounters an increasing force from the beginning to the end of the stroke. Since the leg can exert more force as it extends, this matches the pedal force to the legs ability to generate force.

One approach to determining the spring rate for theses springs is to select them so a resonant condition occurs with the moving leg mass. Let us say the moving leg mass for each leg is ½ the mass of the thigh plus the mass of the shin and the foot. From anthropometric data, that comes to about 13.5% of body weight. With a 170lb. rider that gives a moving mass of 23lb. Let the resonance be at 75rpm or 1.25Hz. That requires a spring rate of approx. 4lb./in. Assume a pedal stroke of 180mm or 7in., then F is 28lb.

28lb at 75rpm and a 14” stroke corresponds to 110W. So at a power level of 110W, the pedal force is zero at the beginning of the stroke and 56lb. at the end of the stroke.  The spring rate could be increased so negative to low forces are encountered at the beginning of the stroke for power levels higher than 110W.
After thinking so much about the Pedicar, I couldn’t resist speculating about a drive-system redesign that would address its shortcomings. I also assumed it would be a banking-three wheeler with front steering. As a result the pedal levers are two-piece with the support link outboard of a two-sided pedal and the input link inboard of the pedal. ( See my crank-rocker design for the EcoVia, above.)

 I have included a synchronizer linkage and accelerator springs to smooth out the pedaling. Instead of the Pedicar’s five speeds covering a range of 6:1, I use a shifting quadrant on the input link that can be rotated over an 8:1 ratio, but a range divided into 21 steps. The 8:1 ratio using 16t freewheels as the one-way clutches required a gear-up mechanism. I incorporated a forward and reverse gear set into that mechanism. Recall that, since the one-way clutches prevent the vehicle from being pushed backward, some means of disengaging the drive or having a reverse gear is necessary to move the vehicle backwards
.
When I stood back and looked at the design, I realized that although it addressed the Pedicar’s design deficiencies, it is probably no-less complicated than the Pedicar’s drive, and no lighter in weight. Since the cost of all-weather human-powered commuter vehicles seems to be the greatest factor preventing their popularity, this would not be a good design approach. An ultra-wide range cassette with a single chainring is cheaper, lighter weight and allows the vehicle to be pushed backwards.

So the next iteration of the EcoVia will pass on the constant-velocity treadle.

There is one circumstance where the constant-torque treadle performs significantly better than conventional circular pedaling is when climbing the very steep hills typically encountered in mountain biking. Outstanding hill climbing performance is mentioned in regard to the American Star of the late 1890s and the Pedicar.
A more detailed explanation of hill-climbing problems associated with conventional circular pedaling can be found in the Kinetic Energy and Cyclic Energy Storage section of the Why Hill Climbing is Hard post.

From the standpoint of power generation efficiency (mechanical power out/oxygen in) producing power in pulses interspaced with rest periods is better that producing power continuously. The extra energy produced during the pulses is used up during the rest periods and this energy is stored in changes in the kinetic energy of the vehicle. If the vehicle speed drops below a certain level, the power cannot remain pulsatile and the rider must produce power around the complete pedal cycle instead of the usual pulses produced from 1 to 5 o’clock in the pedal cycle.

The constant-torque treadle is cadence limited but this is not a problem because the low cadences associated with steep hill climbing are low. The dead spots in the pedal cycle are only momentary with the CTT and torque is produced for almost all of the cycle while the foot only moves through its normal force generating range. Adding acceleration springs just improves the performance assisting foot motion at the beginning of the pedal stroke.

Come to think of it, a few of the restored Alenax Trans-bar bikes were sporting mountain-bike tires.
If Graeme Obree had propelled his streamliner with convention circular pedaling, he probably would have gone faster, but he would only have a prone-rider record. I believe the linear-drive speed record is technically more interesting.

Hephaestus     


Sunday, June 29, 2014

From the Piaggio MP3 to the Toyota i-Road: The Reemergence of the Man-wide Car



I work for a high-tech aerospace company. You would think with all the techie engineers in the place, there would be some interesting vehicles in the parking lot. Except for one vehicle, all the others are pretty mundane. The exception is a Piaggio MP3 three-wheel leaning scooter. It belongs to one of our technicians and, with more enthusiasm than he may feel is justified, I tell him he is riding the future.

The extra wheel significantly increases stopping performance and the ability to lean allows the MP3 to be controlled when the wheels break free on slippery surfaces. This is opposed  to the vehicle falling over if it had just two wheels. While road testing the new 500cc version of the MP3 LT, a Cycle World reviewer dropped (out-distanced) a rider on a BMW R1200GS on a snow-slicked section of curved Berlin highway, a clear indication of the performance potential of a leaning trike. The LT stands for large track, an acknowledgement of the front wheel spacing being over 650mm. In Europe and the UK, if a trike has a track wider than 650mm, it is consider a car and can be ridden without a cycle license or a helmet. Only an auto driver’s license is required.

By making the MP3-LT controllable on slippery surfaces, Piaggio has taken a huge step forward to producing an all-weather scooter.  And with top speed in excess of 80mph and a fuel economy of 60mpg, is offers an attractive commuting alternative to an auto. It just needs a body and it could be considered an all weather scooter, or in a broader sense, a man-wide vehicle or MWV.

In a University of Michigan sustainability study for 2010, vehicle occupancy was calculated to be 1.55 persons per vehicle. That means that for most of our trips and the majority of vehicles there just one occupant in the auto. It is clear that one person in a four-person vehicle is moving too much mass, pushing too much air, burning too much fuel  and taking up too much space.
Most trips could be accomplished using a vehicle tailored to one person or two persons in tandem, a man-wide car. Since the vehicle is lighter and more aerodynamic (less frontal area), fuel consumption could be significantly reduced. And the smaller vehicle size would allow more vehicles to occupy the same lane width as a normal-width vehicle.

The investigations into MWVs by large auto companies are not new. Honda had its EP-X which seated two.

Volkswagen had its L1 which also seated two.

And general motors had its Lean Machine which only sat one.
But only the Lean Machine approximated the width of a motor cycle, 850mm (33.5”), with its 915mm width. Narrow-track three and four-wheel vehicles risk overturning when cornering. Allowing the vehicle to lean like a motorcycle provides  for dynamic stability  and allows the width to remain narrow without the risk of overturning. The Lean Machine was narrower than these other attempts because it could lean.


Now both Toyota and Nissan have MWVs that utilize leaning to reduce the vehicle width. Both are completely electric powered.

The Nissan Land Glider uses four wheels that are articulated allowing the vehicle to lean. At 1100mm width, the Glider is wider than a motorcycle but still significantly narrower than a Smart Car’s 1550mm width. The glider seats two in tandem.



 The Toyota i-Road is also a dual occupant vehicle that is narrower than the Glider at 850mm, mostly due to the layout (like the Lean Machine) where the single wheel does the steering and thus doesn’t require the width that two-wheel steering does. What is unusual about the i-Road is the single-steered wheel is in the rear. If the instability issues associated with rear-wheel steering can be overcome, (see below),


this layout is ideal for packaging. Because the front wheels incorporate the electric-drive motors there is room between them for the driver while maintaining minimum vehicle width and the steered wheel fits easily in the width of the vehicle. 

I attempted to use this layout for the initial design approach of my EcoVia commuter trike, but could not come up with a mechanism for stable control of the steering and leaning that functioned at anything  but low speeds.


Fortunately, the i-Road can utilize active electronic control to insure stability. The i-Road’s top speed is less than 40mph so it is not suited for highway use. What is encouraging is that the project has graduated to the consumer test phase where 20 Japanese drivers will get to evaluate the i-Road under real-world driving conditions.

Probably the most unusual approach to developing a MWV is the C1 from Lit Motors. It uses two gyroscopes to balance the two wheel vehicle. Gyro-stabilized two-wheel vehicles have been around since the dawn of the automobile, but in this case, since the vehicle is all electric, power is available to keep the gyros running temporarily even when the drive motor is turned off. It also features twin retractable support legs that hold the vehicle up when permanently stopped. The amount of balance torque generated by the gyros is impressive and will insure the vehicle stays upright during collisions. It will seat two people. Since it has only two wheels, it will require a motorcycle license to drive.

The i-Road and the C1 are essentially all-weather motorcycles, but for the increased cost, buyers will require significantly more crash protection than your average motorcycle. Providing this will require some creative use of materials and structures to prevent significantly increasing size or weight.

If MWVs become numerous, they may cause changes in highway infrastructure. Single wide highway lanes could be turned into two narrow lanes, and therefore improve traffic throughput. This would require recognition that the smaller vehicles merit special consideration which may be a difficult sell to the general public.

I rented an original Honda Insight when my car was being serviced. Since the car was more narrow that what I had been used to, sitting in the car in my driveway I could imagine the vehicle was only one-seat wide. As long as I am warm and dry and can safely maintain highway speeds, I could live with a vehicle like that.

Hopefully, in the not too distant future, there may be mature MWVs parked in the lot where I work. Maybe one will be mine.

Hephaestus