The Technical History of the Bicycle: Part 1, The Draisienne Seated Scooter

Few would dispute that the bicycle is the most efficient means of converting human power into vehicular motion. It satisfies numerous functions while being extremely simple and light weight, in part, due to the fact that most of its components do multiple roles.  With a bicycle, a runner can double his speed for the same level of effort.

The modern bicycle is a result of multiple contributors to numerous to mention. Most bicycle historians list at least four significant steps in bicycle evolution. Those being:

1.       The Draisienne seated scooter

2.       The velocipede or boneshaker

3.       The ordinary of high-wheel bicycle

4.       The safety bicycle

 Since the ordinary is just a velocipede with un-equal-sized wheels, the above vehicles introduce the three technical innovations I have listed below.

1.       The seated scooter

2.       Leg pedal cranking

3.       Chain and sprocket gearing

It is hard to over emphasize all the factors that fell into place when Karl von Drais invented what he christened the laufmachine (running machine). Von Drais had studied mathematics and mechanics in Heidelberg but worked as the master of forests for the Duke of Baden. It has been speculated that he was looking for a faster alternative to walking the forest paths when he invented his seated scooter, now known universally as the Draisienne.

As one would expect it all begins with the wheel and walking. If, in the early 1800’s, you didn’t have a horse, you walked from place to place, or ran if you were in a hurry.  To explain the popularity of the Draisienne, it is useful to compare it to walking and running using four factors involved in a moving human.

Stride length

Cadence

Efficiency

Postural support

Speed is the product of cadence and stride length. (Stride length is analogous to gearing in machinery).  Now, runners go faster than walkers because their cadence is higher and their stride length is longer. A walker’s stride length is just the maximum spacing between the feet at the end of a step cycle, because, by definition, a walker always has one foot on the ground. A runner, on the other hand can have both feet off the ground simultaneously. As a result, during the period of time that the runner is flying through the air, the effective stride length is increased over the maximum foot spacing.

 The great Cuban middle-distance runner Alberto Juantorena airborne.

With walkers, rearward leg motion is accompanied by the entire body moving forward.  With runners, the period of the leg accelerating the body is shorter and when airborne the motion of the leg is only moving the mass of the leg. So, on the average, the runner’s leg motion is associated with significantly less mass than is the walkers. For a given force, the acceleration can be greater when moving a lesser mass, so a runner’s cadence is higher than a walker’s.

A wheel rolling on a horizontal surface provides vertical support but allows horizontal motion with low resistance. Von Drais realized that if you supported a rider on a wheeled vehicle whose seat height required that the leg be almost completely extended to touch the ground, the airborne phase of running could be extended into a gliding phase where the backward leg stroke resulted in an enormous stride length. Even though the forward speed of his running machine could not exceed the maximum speed the leg could be moved rearward, the time that the vehicle stayed at that speed was longer and therefore running speed could be maintained with less effort.

Von Drais may not have appreciated that, as a result of the short-duration kick and long-duration glide associated with the running machine, the aerobic efficiency of moving the vehicle was improved over walking and running.

For a given level of aerobic power generation, the oxygen consumption is lower if the power is produced in short-high-amplitude pulses with longer rest intervals as compared with longer-lower-amplitude pulses with shorter rest periods.  As a graduate student, I was able to demonstrate this effect using a pedal drive with an adjustable, cyclically-variable-gear-ratio. I measuring instantaneous mechanical power, average mechanical power and oxygen consumption. My speculation as to the cause of this effect is that the longer rest periods between the power pulses are more conducive to replacement of chemical stores in the muscles than during activities with shorter rest periods.

And, since the rider was seated and could additionally support his body with his arms, the running machine reduced the energy necessary for postural support when compared to walking or running.

Now all the gains associated with the Drasienne could be realized as long as the weight of the vehicle was not excessive. This was no mean feat when wagons and carts were constructed mostly of iron and wood. The obvious solution to minimizing weight was to limit the number of wheels the vehicle had, but could one make a controllable vehicle using only two wheels? Despite the biomechanical improvements associated with a kick-and-glide propulsion approach, the real quantum leap von Drais made was creating a two-wheeled vehicle that could be balanced.

The fascinating thing is that there were no precursors to the Draisienne. Earlier bicycle historians postulated that things began with a child’s stick horse. A wheel is added to the bottom of the stick, and then another wheel is added inline with the first. This is then scaled up to adult size and the antecedent of the Draisienne is created. Not only is there no solid historical evidence for this scenario, but more importantly, the two wheel version of the stick horse could not be balanced.

 Here is a key point. The ability to steer is necessary to balance an inline-two-wheeled vehicle.

Why are steering and balancing linked in the function of a dynamically-stable two-wheeled inline vehicle?

Let me propose a simple model of the bicycle-rider system, possibly a bit too simplistic for the academic dynamicists out there and it does leave out things like the precessional effects of the wheels. But it did aid me in understanding what was going on during ten years of experimenting with rear-steering recumbent bicycles.

The two mechanisms that allow a bicycle-type device to balance are castor and lean-steer. Consider the bicycle as a system with two masses and three-degrees-freedom for motion. The front mass consists of the wheel, fork and handlebars. The back mass consists of the rider and the rest of the vehicle. The front mass is attached to the back mass by a pivoting connection. From a disturbance standpoint, we will ignore one motion DOF, that being the bicycle moving forward. The disturbance motions are the fork mass pivoting with respect to the frame mass and the frame mass leaning from side to side. The two disturbance motions are not independent and the nature of their coupling is determined by the steering geometry of the vehicle.

Now for castor to occur, the contact point of the front wheel with the ground must be located behind where the steering axis intersects the ground, where behind is defined as opposite the direction of motion. For any angular disturbance of the fork mass, castor results in a moment being generated that tends to reduce the disturbance until the contact patch is inline with and behind the steering axis.

Lean-steer occurs along castor as long as the steered wheel is at the front of the bicycle. As you lean a bicycle to the side you will observe that the fork mass rotates toward the direction lean. A disturbance that causes the frame mass to lean results in the fork mass steering the vehicle in the direction of the lean. The vehicle is now going in a circle and the radial acceleration associated with the change in direction picks up the frame mass and corrects for the lean disturbance.

So the amazing thing is that von Drais could not evolve his design based on non-steered precursors but has to create it in one quantum-leap of imagination.

Notice for the Draisienne restoration above the steering axis appears to be located near the front of the triangle supporting the front wheel and the axis is near vertical. The contact point “trails” the steering axis by almost half a wheel diameter. Compared to a modern bicycle with several inches of castor, the Draisienne has a many times that. However, the friction associated with the largely wood on wood steering pivot is much greater than that associated with a ball-bearing steering headset. The torque of the castor moment must overcome this friction to return the fork mass to being aligned with the direction of motion.  So a significantly greater amount of trail would make sense.

The weight of the Draisienne was about 44lb. With no cushioning from pneumatic tires or frame compliance, let alone suspension, the ride must have been bumpy on all but the smoothest of roads. Prior to inventing the Draisienne, von Drais was a forester. The mountain biker in me would like to imagine him gliding along smooth single-track trails, but there is no documentation of this. Since horse’s hooves and rain make for very bumpy roads, the opportunities for extended gliding might have been less than frequent.

There we numerous variations on the Draisienne, mostly involving changes made in the materials of construction but probably with little weight saving. Whether referred to as the Draisienne, the hobby horse or the dandy horse, the outlines of the modern bicycle are unmistakable. It would take over 40 years for the next step in bicycle evolution to be invented.

Hephaestus

The Prius Electric Bicycle at the Detroit Auto Show

The Detroit International Auto Show has been going on this week and the unanimous star of the show is the new 2014 Corvette Stingray. With 450 horsepower, 450 ft.lb. of torque, a seven-speed manual transmission (starting to sound like derailleur transmissions here) and a 52K$ price tag, the ‘vette excited a lot of sports-car minded attendees and journalists.

While the Corvette launch is typical fare for large auto shows, what is less typical is the presence of vehicles at the other end of the horsepower spectrum, electric bicycles. Both Toyota with its Prius Parlee and Daimler AG with its Smart E-bike displayed models.
 

http://www.triplepundit.com/2013/01/years-detroit-auto-show-concept-car-bikes/

 The Smart bike is shown below.

This is not the first time that vehicles with pedals have show up at large auto shows. In 2011, Ford displayed an E-bike at the Frankfurt Auto Show, but Europe has always taken the bicycle more seriously that the US as a transportation alternative to the car. I like to think that the appearances of these bikes in Detroit is an acknowledgement that human-powered commuter vehicles are playing a more significant role in the transportation matrix

.

Now, while pedalectric bikes offer one form of hybrid human-powered commuter vehicle, they are ill-suited to commuting in inclement weather. An extensive discussion of the characteristics of an ideal HPCV are discussed in “Rx for a Healthy Commute”, below

http://lefthandedcyclist.blogspot.com/search?updated-max=2012-02-07T19:09:00-08:00&max-results=7

Now to get displayed at a large auto show, a HPVC needs to be a product of an auto company, like Toyota or Daimler AG. Even though they are developed by non-auto-company enterprises, there  was one vintage and is one new vehicle that deserved and deserve to be displayed to the general car public at a large US auto show.

One HPVC was the Pedicar from 1973, below.

 http://lefthandedcyclist.blogspot.com/2012_04_01_archive.html

Production of the Pedicar was only 20 vehicles. It didn’t catch on, even though there was a gas crisis going on during its public release. At $550, the cost may have been a deterrent when compared to a bicycle and, even though similar vehicles were used in Europe after WW2, US consumers were just beginning to think of bicycles as commuter vehicles.  If it had an electric assist, which it was ideally suited for, it might have experienced the sales it deserved.

The auto companies did take notice of the Pedicar, however. An industrial designer from Chrysler drew this lampooning cartoon of it.

A modern vehicle which deserves recognition at a large US auto show is the Drymer trike from the Netherlands. With a bit more weather protection, the Drymer would be an ideal all-weather pedalectric commuter vehicle.

http://lefthandedcyclist.blogspot.com/2012/02/drymer-and-varna-lean-forward.html

So the future is looking up for human-powered commuter vehicles. If the general public begins to consider pedalectric bicycles as viable transportation alternatives, they may be ready to accept and purchase vehicles like the Pedicar and the Drymer.

Hephaestus

The Pedal-powered Porsche and the Ultra-Efficient Car

A lot of bicycle technology was incorporated into early automobiles; ball bearings, pneumatic tires, the differential and the list goes on. The efficiency demonstrated by modern human-powered vehicles should be an example for potential improvements in car design. While the two art-piece cars on view below are seen as jokes by the car community, they serve as a departure point to discuss a possible directions for aerodynamic improvements for that most popular commuter vehicle.

http://www.youtube.com/watch?v=GaQB_tgS7f0

I don’t recall how I stumbled on the pedal-powered Porsche. After discovering it I asked the machinist at work, who is a Porsche devotee, about it and he just laughed. It seems it is a big joke among sports-car buffs. The people at Top Gear knew all about it. Driven by Richard Hammond, it holds the record for the slowest lap on their test track.  And there is a follow-on Enzo-Ferrari-like vehicle which appears to be slightly more aerodynamic due to the fact that the Enzo is based on a formula one (F1) car layout. More about the F1 layout later…

http://www.youtube.com/watch?feature=player_embedded&v=ISEGDWpKAeY

Now clearly, both these vehicles, created by Hanes Langder, should be categorized as art pieces. Weighing 100kg and having a huge aerodynamic footprint compared to any enclosed recumbent tricycle; the vehicles cannot be expected to be even as fast as an upright mountain bike. Nevertheless, the human-powered vehicle builder in me is bothered by the laughter associated with the vehicles. Pedal-powered vehicles can be viable transportation alternatives, especially with a small power assist, but the vehicles need to be ultra efficient for 1/3^rd of a horsepower (250W) to be able to move the vehicle at anything greater than a walking speed. 

http://grynas.delfi.lt/tv/article.php?id=51610123

In contrast to the Ferdinand and the Fahrradi, RJK pedalectric velomobile is intended to be a viable commuter vehicle. I have no idea of the weight, but the cross-section of the vehicle appears to be smaller than Herr Langder’s creations, even if the open cockpit incurs more air drag. Of interest is the RJK has front-wheel drive and rear-wheel steering, which may result in a weight reduction from a shortened drivetrain. However, the vehicle’s speed in the video, with one peddler, does not seem to be very fast.

A minimal weight, minimum cross-section, maximum streamlined recumbent bicycle, such as the Varna Tempest, can probably cruise at about 50mph given a 250W input power.

Unfortunately, low visibility, difficult entrance and egress, limited steering etc. prevent such a vehicle from being a practical for commuting. The posts on this blog have spent probably an excessive amount of verbiage discussing how to optimize a vehicle that would use the bike lanes for commuting. See “Rx for a Healthy Commute”, below. But how could the lessons learned from human-powered vehicles make a more efficient car?

These lessons are minimize air drag, minimize weight and minimize rolling resistance. This discussion will primarily focus on efforts to reduce air drag. Weight reduction is assumed to come through use of lightweight materials, space-frame and/or monocoque construction techniques and optimization of load paths that route the payload weights as directly as possible to the wheels. Narrow profile, high-pressure tires would reduce rolling resistance.

Air drag is proportional to the cross-sectional area of the vehicle, the drag coefficient of the vehicle’s shape and the cube of the vehicle’s velocity. The goal in streamlining the vehicle is to reduce the form drag, the product of the area and the drag coefficient. If the form drag gets very low, then skin drag gets significant, and it is beneficial to reduce the total-wetted surface area of the vehicle.

The conventional-rectangular four-wheel layout for cars does not lend itself to being enclosed by classic streamlined shapes.  The difficulty lies with the wheels. Early cars left the wheels exposed and concentrated on enclosing the passenger and engine compartment, the fuselage. Since the top of the wheel is moving a twice the velocity as the vehicle, a rotating wheel has more drag than a static one. When the aerodynamics of the vehicle became more of a concern, the logical approach was to use a streamlined shape (teardrop) for the fuselage and enclose each wheel in a streamlined wheel pant as well. The structure that attached the wheels to the main fuselage also needed to be streamlined, often with wing-like sections. This approach minimizes the vehicle cross-section but results in added interference drag where the various streamlined elements came in contact with each other. The typical result is similar to the 1938 Hispano Suiza Xenia shown below.

Or the contemporary Enzo Ferrari …

This aerodynamic layout, enclosing with the fuselage and wheels separately originated with early motorized carriages. I like to think of it as the F1 layout, even though F1 cars cannot enclose their wheels.

The alternative approach is what most contemporary cars employ, enclosing the entire vehicle in one or more streamlined shapes. The upside is that interference drag can be reduced while the downside is the cross-sectional area of the vehicle is increased and the aero shapes are less conventional and less efficient. If the vehicle area must expand excessively to allow the use of a shape with a low drag coefficient, the resulting vehicle may not benefit from an overall reduction in form drag. The Schlorwagen, below, has a low drag coefficient of .15 and looks very streamlined from the side view.

 


 But in the front view, the cross-sectional area of the vehicle appears to be rather large.

The track (transverse wheel spacing) for the rectangular-wheel layout is determined by the width of the fuselage and the roll-over resistance of the vehicle when cornering. If the passenger compartment can be kept narrow, for example if the seating is reduced to two people in tandem, and the vehicle is allowed to lean like a motorcycle, that the cross-sectional area can be additionally minimized. See “The Drymer and Varna Lean Forward” below.

Going to a three-wheel layout can bury one of the wheels in the fuselage and thereby improve the drag coefficient, especially if the steered wheel is buried. The downside of this approach is that, for a given rollover resistance, a three-wheel vehicle must be approximately 50% wider track than a four-wheel vehicle. This adversely increases the cross-sectional area.

For simplicity, this discussion will concern itself with the more-conventional four-wheel rectangular layout. 

The design team at Edison2, who won the Progressive Automotive X-Prize for a four-wheel, four seat vehicle that bettered 100mpg, have been refining the F1 layout with the second iteration of their Very Light Car.

Interestingly, the top view of the Very-Light Car Mk2 looks a lot like a modern version of the Hispano Suiza above albeit with a much greater degree of fender seperation and more streamlining. Edison2 is probably at the leading edge for efficient vehicle design, both in aerodynamics and lightweight vehicle construction.

One means of reducing the air drag even more than the Very-Light Car is to narrow the passenger compartment by going to two-passenger tandem seating, similar to the Messerschmitt car from the 1950’s.

 It is of interest that the earlier Messerschmitts were three-wheeled with the single-driven wheel in the back. This is a later version which employed a larger engine. The rear seat of the Messerschmitt could hold a second person or haul cargo. An interesting design feature (shared by my friend Jerry Onufer) was that the center of gravity, c.g., of the vehicle was located in the rear-seat compartment. The idea was that the vehicle’s dynamic performance would remain independent of the load that was being carried in the rear seat.

So the vehicle I envision is similar to the So-Cal Bonneville streamliner in the photo at the beginning of the article. I would use narrower tires enclosed in wheel pants and the structure connecting the wheels to the fuselage would fit within horizontal wing shaped enclosures. Assume a vehicle height of 40” (that of a low sports car). If the c.g.is lower than 20”, for a one-gee rollover resistance the track could be 40”. This is less than ½ the track of a typical car. There could be some additional benefits to having such a narrow vehicle, since it takes up less width on the road.

Once you have a design for a vehicle that is aerodynamically efficient and light weight any source of motive power will benefit from the vehicle’s efficiency. I do not believe that electric propulsion is the magic bullet that solves fossil-fuel consumption problems. If the vehicle design allows for an extended driving range with batteries, the vehicle will get exceptional gas mileage with an internal-combustion engine as well.

The above being said, I envision the tandem ultra-efficient car being propelled by a hybrid power plant. The power source would be a small gas turbine driving an electric generator. The electricity from the generator would, in turn power an electric motor located in each of the four wheels. There would be onboard batteries to provide for increased power for acceleration and regenerative braking. There will be a weight penalty for using four motors instead of using one motor with four times the power. Having a motor in each wheel also violates the suspension principle of minimizing unsprung weight. On the other hand, having motors in each wheel that can be controlled independently eliminates three mechanical differentials as allows for unprecedented traction optimization under microprocessor control. Volvo used a turbo-generator and wheel motors in a concept car during the 1990s and Jaguar used twin turbo-generators more recently.

The X-Prize-winning Very Light Car weighed 830lb., was powered by a 30kW IC engine and had a drag coefficient of .16. Could a tandem two-seat version maintain the same drag coefficient, significantly reduce the cross-sectional area, weigh less than 200lb and be powered by a 7.5kW turbo generator? And would a pair of pedals get you to a gas station if you ran out of fuel?

Hephaestus  

The Return of the Recumbent Bicycle

Last September, after allowing it to gather dust in the garage for the last six years, I started riding my Avatar 2000 recumbent on the road again. I had forgotten how much fun it was to cruise down the road sitting with a car-like posture and taking in the scenery instead of being hunched over the handlebars with only a narrow view of the road ahead. I also had forgotten how awkward hill climbing was; dropping into the granny ring and spinning as if my life depended in it. Yes, my relationship with my recumbents was a love and hate thing.

My relationship with recumbent bicycles began three years after I purchased my first derailleur bicycle, a gas-pipe-framed Schwinn 10 speed. I bought the April 1969 issue of Popular Mechanics because it had an article by the do-it-yourselfer extraordinaire, Robert Q. Riley. The article was about the construction of a low-slung bicycle he called the “Ground Hugger”. I had never seen anything like it and started thinking about how I could build one.

 

As the article said “You’re cradled in a bucket seat and as you lean into a long-banking turn, you have the exhilarating sensation of being on a toboggan with wheels”. To a cyclist, this was an exciting prospect.

Many in the non-cycling community believe that Riley invented the recumbent bicycle. Instead Riley had copied the essential elements of a bicycle designed and built by the ex-airline pilot and bicycle innovator Captain Dan Henry.

Henry, famous for the Dan Henry markers used to guide cyclists on organized rides, wrote an article for the May 1968 issue of Bicycle Magazine describing his recumbent. He designed it based on what he felt were the best characteristics of pre-WW2 recumbent bicycles.

While Riley never admitted copying Henry’s recumbent, the similarities between the designs are numerous, especially the long wheelbase and remote steering. While Henry used a chain and sprocket for the fork-steering connection, Riley used a Cardan universal joint from a socket set. Why neither of them used the much simpler connecting rod between an offset pivot on the handlebars and one on the fork, I do not know. One interesting consequence of the use of a u-joint is the coupling ratio varies with the position of the joint. This could be used to improve steering control by having the steering be least sensitive when the steering is straight and becoming more sensitive with increasing steering lock. (Riley may have seen that the preWW2 Velocar used a Cardan joint to connect the handlebars to the fork.)

(A note here that chopper-style kid’s bicycles like the Schwinn Stingray are technically semi-recumbent bicycles and, for that matter, the children’s Big Wheel tricycle and its variants are recumbents. Here I am only interested in the reemergence of the adult recumbent bicycle.)

Henry was not the first to experiment with recumbent bicycles since WW2. Gunnar Fehlau, in his book “The Recumbent Bicycle”, describes the obscure work of the engineer Paul Rinkowski on short-wheelbase recumbents starting in the late 1940’s and continuing on for four decades.

And then there is this fascinating picture of two riders on very-low Grubb-style recumbents in Popular Mechanics from March of 1952. Notice, in this case, that the remote steering uses cables to connect the under-seat handlebars to the forks.

In addition, Alex Moulton of small-wheeled-bicycle fame experimented with a Grubb recumbent prior to settling on an upright posture for his improved-bicycle design in 1962. Moulton found that recumbent pedaling produced thigh fatigue when pedaled for extended periods and rejected the recumbent approach. It was a lost opportunity for recumbent evolution, given Moulton’s innovative product improvement abilities.   

Henry’s recumbent bicycle may have influenced the east-coast arm of the subsequent human-powered vehicle movement, Prof. David Gordon Wilson of MIT. He must have been aware of Henry’s article, because he wrote an article, “Where Are We Going in Bicycle Design?” published in Bicycling the previous month. He also included a photo of Henry’s recumbent in Bicycling Science, the book he coauthored with Frank Roland Whitt in 1974.

From 1967-1968 Wilson sponsored a design competition for man-powered land transportation. The winner, W.D. Lydiard, designed and actually built an enclosed mid-wheelbase recumbent bicycle. Traditionally recumbent bicycles either had the cranks behind (long wheelbase) or ahead of the front wheel (short wheelbase). Those with a long wheelbase were inconvenient to transport and had a lightly loaded front wheel that could wash out on slippery surfaces. The short wheelbase designs had an overloaded front wheel that consequently resulted limited-front-tire life and in skittish handling. If the cranks are located in the ideal location, above the front wheel, the bottom-bracket height was usually so high that the rider is placed in an uncomfortable posture. I refer to the issues with these approaches as “the recumbent packaging problem”. Refer to “Recumbents and Convergent Evolution”, below.

     

To reduce the pedal height, yet maintain their location over the front wheel, Lydiard used a squashed pedal path generated by a crank-slider-type mechanism. Lydiard felt that this approach could be refined to eliminate the problem of interference between the feet and pedals when putting the feet on the ground.

Wilson was apparently quite captivated by Lydiard’s mid-wheelbase, squashed-pedal-path approach. In a private communication, Wilson shared 17 permutations on this design approach, the latest being dated 1977. To my knowledge, none were actually constructed. Based on one of Wilson’s drawings, I built up a crank-rocker or treadle mechanism for my EcoVia 2.2, but power-production limitations caused me to abandon the design. See “Transcending the Pedicar, Part 2”, below.

In 1972, while Wilson was designing linear-drive recumbents, H. Fredrick Willkie, being inspired by Wilson’s design completion, contacted him for a sketch for the design of an advanced bicycle. Interestingly, the recumbent that resulted from that sketch didn’t utilize a linear drive. Ultimately there were five iterations in this design exercise, culminating in the Avatar 2000. Willkie did two designs which he christened “Green Planet Specials”. The first version had handlebars in front of the rider’s chest connected directly to the fork and a high bottom bracket. The design was very similar to the preWW2 Rivat recumbent. Willkie found the compressed body posture uncomfortable and at Wilson’s suggestion, the second version had a lowered bottom bracket and a more leaned-back seat angle. In addition it had direct steering with the handlebars mounted beneath the seat. Wilson bought the GPSII from Willkie and continued to modify the design as the Wilson-Willkie. The seat back was made more vertical and the weight on the front wheel was reduced from about 70% to about 65%. The Avatar 1000 followed and the front-wheel loading was reduced to about 62%. Finally, with the Avatar 2000, the radical step was taken to move the front tire ahead of the bottom bracket, and the front wheel loading dropped to about 31%. Under Wilson’s guidance, two Boston-area bicycle builders, Richard Forrestal and Harald Maciejewski began manufacturing the Avatar 2000 in 1979, making it the first production recumbent since WW2. (A more comprehensive description of the evolution of the Avatar recumbent, including photos of the five vehicles above, can be found in Wilson’s article, “Evolution of Recumbent Bicycles and the Design of the Avatar Bluebell” in the proceedings of the Second International Human Powered Vehicle Scientific Symposium.    

The Avatar 2000 recumbent was very similar to the preWW2 British Grubb recumbent. Both use indirect steering with the handlebars coupled to the fork by a connecting rod. Differences were the Avatar’s seat was higher and more upright and the Avatar had a shorter wheelbase due to the use of a 16” front wheel.  The Avatar’s wheelbase is 63”.

So there is a circuitous linkage between the Ground Hugger and the Avatar 2000.

In 1984, after becoming somewhat bored with upright bicycles, I purchased an Avatar 2000 from Angle Lake Cycle in Seattle. It was serial number 085 and it had been sitting in the store window for several years.

I was disappointed with both the on-the-level speed and, even more so, the hill-climbing speed of the Avatar. On the positive side, the extreme comfort riding the Avatar on the level terrain somewhat compensated for the reduced speed by eliminating fatigue from secondary effects like a sore seat, sore back and numb hands.

I did make one component change that significantly improved its hill-climbing ability. I replaced the conventional cranks with a Power-Cam crankset which I had purchased several years before.

The Power Cam was invented by Dr. Lawrence Brown of IPD (International Patent Development). The design involved chainrings that could float relative to the cranks. A cam follower attached to the cranks rode on a cam attached to the bottom bracket and drove the chainrings through a gear sector. The inertia of the bicycle kept the chainrings rotating at a near constant speed and the cam mechanism caused the cranks to speed up and slow down relative to the chainrings as a function of pedal position. The net result was the mechanical power pulses during pedaling became shorter and larger than with a conventional crankset using round chainrings. As a consequence, the rest periods between the pulses (two per cycle) became longer. The longer rest periods are physiologically more efficient and, for a given oxygen consumption, the aerobic power output was increased. (More on factors influencing power production in a future post.)

Using a Power Cam on a recumbent was suggested by Edward P. Stevenson in his book “The High-tech Bicycle”. The Power Cam did not work well when standing up on the pedals and forced you to climb seated. On a recumbent you couldn’t stand on the pedals so a Power Cam on a recumbent made a kind of sense. Stevenson was correct and it improved hill climbing. The Power Cam had only two chainrings, however, so an adaptor plate was machined to allow the mounting of a third granny chainring.

The increased comfort of the recumbent posture allowed me to take longer rides than on my upright and I logged a lot of miles over the 22 year period between 1984 and 2006. I eventually added an arm-power attachment to the Avatar to scavenge some of the power I was loosing through the inefficiencies of my leg pedaling. See “Arm Power and the Avatar Recumbent” below.

In 2006 I started mountain biking regularly and put the Avatar in moth balls. I began with a hardtail and later purchased a full suspension bike. My hardtail acquired road tires and became my road bike. I didn’t ride on the road much, however, because of numb hands and tired back from sitting in one position for extended periods. I didn’t have this problem when riding on dirt because of a continuingly changing body position and the reduction of road vibration due to the full suspension. The level of comfort riding an upright bicycle off-road was acceptable.

It was on a car trip up to Snoqualmie Fall for breakfast on Labor Day that I was reminded of the number of time I had ridden the scenic hill climb up to the falls on the Avatar. I have never done that ride on my converted mountain bike because of the associated lack of comfort. Realizing what I had been missing the last six years, I decided I would ride the recumbent on the road and the upright on dirt, thus having the best of both worlds.

The first few miles back on the Avatar after the six year hiatus were a bit shaky and the long hill climb back home was a painful grind. But when riding on the flats what I was left with was the feeling of being in a touring car where I could comfortably view the scenery while exercising at the same time. For me, the recumbent bicycle has returned.

Hephaestus