LOTUS 108  and 110 
Britain has a long and successful tradition of competition cycling. This has enjoyed something of a Renaissance since Chris Boardman’s famous Gold Medal at the Barcelona Olympics in 1992. [4km pursuit] riding the Lotus Pursuit bike.
Currently the British cycling team have high expectations in the London Olympics of 2012.The subject is very topical as are the green credentials associated with cycling in general.
Much of this triumph and perhaps attendant motivation can be attributed to design innovation associated with the Lotus 108 Pursuit bike of 1992.
Although the A&R has its primary focus in the Chapman era the editors felt that the Lotus Pursuit and Sports bike has such a strong affinity with the Chapman mantra and methodology it was worthy of a more detailed evaluation.
Technology and materials make significant contributions in many sports disciplines including tennis, bob sleigh, swimming, pole-vault, sailboards, hang- gliders, javelins, jogging shoes, ski boots helmets and clothing. Carbon fibre is used in golf clubs to kayaks to aerospace and racing car components.
Chapman Mantra/ Methodology
Stated simply this was total commitment to the lightest possible construction and materials. This followed the rules of physics and mechanics. Lightweight was a function of performance and handling. The rules are universal wherever weight, speed, distance are engaged. The less weight the faster an object can accelerate, decelerate, and manoeuvre and its top speed is likely to be for given energy input.
Decrease in weight commences the beneficial spiral permitting further reductions.
The application of science particularly aerodynamics to improve efficiency, reduce drag or resistance to complement and integrate mechanical efficiency savings.
E.g.: An aerodynamic body on a car will require a lighter / smaller engine to achieve same result as a heavier engine in non-streamlined vehicle. However the lighter engine will make possible a lighter frame and components etc.
History of Bicycle–Briefly
Da Vinchi bicycle? Sketch c 1490
De Servac : Celerifere
Baron Karl von Drais style “Hobby horse”c 1817
Macmillan treadle cycle 1839
Michaux’s velocipedec 1861
“Ordinary” Bicycle c 1870 “Penny-farthing”
Rover Safety bicycle by John Kemp Starley c 1885 –England
Pneumatic tyres developed by John Boyd Dunlop in 1888
1933 French Velocar [reclining / recumbent] designed by Francois Faure.
c1946 Ben Bowden’s “Spacelander”
1984 Francesco Moser Hour Record Bike. [51.15km [31.78miles]
c1986 Burrows Windcheetah Carbon Cantilever
1992 Chris Boardman, Olympic Record. Lotus Sports Bike 108
2012 British International Cycling: Chris Hoy etc
For many the bicycle is considered the most efficient form of transport on earth. Its credentials are:
Economical to own and run
Reasonable safe [inherently accept for contact with other motor vehicles]
Easily personalised / customised and adapted to individual needs
Synthesis of body and machine; art/craft, technology and engineering
As concerns grow for the environment so do the interest and importance of the bicycle. Some argue that the automobile advantages are being outweighed.
The bicycle in comparison is ecological, efficient and more sustainable and generally holistic when fitness and health are factored in.
Manpower and Horsepower
Ballantine and Grant quote as US study that explained to cycle one mile burns 35 calories, to walk 100 calories while a car engine burns 1,860 calories.
With a rider producing 0.25 hp a conventional bike will travel at approximately 21 mph [34km/h]. 0.5 hp is required to produce just 26mph [42km/h]
It’s believed that a rider producing .25 can deliver 21mph or 0.125 can achieve same speed when using a body shell recumbent
The equation to calculate traditional power is:
Power=Work/ Time=Force distance/time [1 minute]
A healthy human might produce 1.2hp
Trained athlete 2.5hp
It’s thought that a reasonably fit pedestrian can walk at 4-5 mph. However on a bicycle with an increase of weight of 1/11 or 1/12 body weight and assisted by the mechanical efficiency of gears a competition cyclist might achieve slightly over 25 mph.
If the reader google’s cycling performance there are several formulae that can be adopted.
Requirement of Efficient Cycling:
Are that it should be strong, light responsive with low resistance .
The bicycle is a machine rather like a car and can benefit from the application of mechanical efficiency. Hence light weight and aerodynamics enable the power generated by the rider to deliver more and for agility / manoeuvrability to increase. A bicycle is significantly affected by aerodynamics. The cyclist body creates significant wind resistance at 30-50km/h [20-30mph]. This can be reduced by approximately 25% by adopting a crouched riding position and the use of aero bars [aero tuck].
The two most contributory components are the frame and wheels.
The bike was ripe for technological evaluation and improvement and this is what Burrows and Lotus achieved
Names and Definitions
It can be a little difficult to grapple with the terminology. The carbon fibre framed bikes have been referred to as:
What the editor’s belief they allude to is:
A non-traditional frame without conventional tubes.
A frame designed for both lightness and aerodynamics. Hence mono [single sided] blade front fork
A frame / chassis in a single plane i.e. with single sided front and rear wheel fixing. [Avoiding the splayed front and rear fork conventional mounting that nearly double the width of the machine and in process increases resistance.]
Carbon fibre is a synthetic material and used in aircraft. It’s believed it may have been developed at the Royal Aircraft Establishment, Farnborough from the 1960’s.
The 108/110 are bicycles with an aerofoil section composite monocoque frame, [or chassis] this is moulded using advanced materials but primarily carbon fibre. It also has bonded alloy inserts for the headset, bottom bracket and rear wheel axle bearing.
In the late 1980’s frames of carbon fibre might weight 1.02kg [2lbs 4 oz] but further reductions have been achieved and sub 0.9 [2lbs] are possible.
Carbon fibres can we woven with strands of thermoplastic or glass fibre epoxy composite and graphite fibres into which alloy inserts accept the headstock and bottom bracket and rear axle bearing. Carbon fibre is stronger, lighter and stiffer than steel or aluminium.
It therefore meets the requirement of high performance that demand minimum weight with high tensile resilience.” Carbon fibres have high elastic modulus values [up to 5 X that of steel] and make excellent reinforcement. Usually loosely woven into a type of cloth the fibres are laid in a matrix according to strength requirement of the design- arrears where the fibres are more closely woven will be the those of greatest stress”
After the frame, wheels are the most significant component. Two factors are critical:
As wheels spin angular momentum creates gyroscopic effect. The heavier the wheel and faster it turns the greater the force.
Consistent with the aerodynamic form on the Lotus 108 both front and rear wheels are cantilever and fixed by stub axles i.e. the wheels are held / fixed on one side only. [I.e. there is no wishbone, thus reducing width and improving penetration]
Although it ought be mentioned the 110 Sport bike was fitted with the splayed front wishbone type fork.
Disc wheels possess less aerodynamic drag over conventional spoked wheels. [About 50% at 18km/h [30mph] torque] Disc wheels can be used on the back. They are structurally stronger and more aerodynamic. They rear wheel does not suffer the wind sail effect [i.e. subject to wind pressure impacting on steering/ direction] to such an extent and is partly faired or shielded by the rider and the frame.
Composite spoked wheels are used at the front on both the 108 and 110. This type of construction is preferable to a disc at front as it avoids the wind sail effect they have approximately 50% open sided area. Each spoke acts as an aerofoil. They are heavier but provide extra speed.
Fixing can be made integral with the monocoque. On the Lotus 108 Mavic wheels and rims were used, either spoke and disc. The 110 Sport bike used Mavic or Spinergy composite front and rear.
It’s believed that the Specialised Du Pont composite wheels might have been used as an alternative on some of the Lotus bikes. These are thought to have been constructed with carbon fibre on a foam core with a bonded 6061 T6 aluminium rim. In spoke fashion there is approximately 50% open area that reduces vulnerability to cross winds. This type is safe for both front and rear.
The front wheel may be smaller in diameter, [24”] creates less drag and benefits from less weight and carries through to smaller frame and further weight reduction. However rolling resistance offsets some of these gains. However a 700C wheel replacement was adopted on later machines of the Lotus108.
Tyres are usually very light, with smooth tread for lowest drag. Often inflated with helium to further reduce weight. Tyre pressures can vary from 105psi to 200.
Mike Burrows: The Designer:” You’ve been framed”
Mike Burrows is the engineer/enthusiast/ inventor believed to be the originator /designer of the monocoque frame. He was born in 1943 and has remained a resident of Norwich and its environs [note the geographical proximity of Lotus at Hethel] In 1984 Francesco Moser’s frame we see evidence of a conventional tube frame in the process of evolution with a frame layout/ geometry aiding aerodynamics. Note this machine used disc wheels.
Evidence suggests that Burrows first attempt to progress forward was the c 1986 Windcheetah Monocoque/ Windcheetah Carbon Cantilever .The construction comprised a streamlined monocoque frame made in carbon fibre. The monocoque eliminates traditional tubes and creates a more streamlined frame. The major components are held all in one piece. A single fork front wheel blade sometimes known as “mono-blade” is fitted [this was initially believed to be cast aluminium but later replaced with carbon fibre.] The advantage being both lighter weight and reducing drag. Both front and rear wheels were spoked but the front smaller [61cm /24”] in diameter partly to make faster handing but also lower the front to aid aerodynamics and contribute to a shorter wheelbase. [94cm] The handlebars were conventionally mounted and slightly upturned. They are referred to as “Gull-Wing”. They provide aerodynamic advantage. The seat post was integral with the frame. Transmission was a single fixed wheel. The rear sprocket in a conventional position that required the chain to run through a cut out in the frame. It’s believed that a single front hub brake was deployed.
This single fixed gear bike was believed to weigh approximately 9kg [20lbs]
Mike Burrows also designed the Racing HPV Windcheetah SL Mk.VI “Speedy” in 1995.This was a recumbent tricycle with low centre of gravity. Provides quick steering through joystick, good handling and powerful brakes [twin drum on front wheels]. The frame was monocoque [“mono”] whilst titanium, aluminium and Kevlar were also used.
The editors believe there is some small ambiguity surrounding the originality or commissioning of the monocoque frame.ie there seems to be varying evidence that suggests Burrows made the original design which was passed to Lotus Engineering for development. The alternative being that Lotus saw a market opportunity and asked Burrows for an initial design. The editors believe the former to be more correct.
Lotus made a very significant contribution through:
Secret testing and development through early 1992
Design input founded around FI experience of structures and materials
Wind tunnel testing opportunities that resulted in the optimum shape.
According to William Taylor in the “Lotus Book” success of the 108 “Prompted Lotus to join forces with a major South African manufacture. Cape Town based Aerodyne Technology, to develop the pioneering bike with a view to securing a commercial future for a range of Lotus sports products”
This became the 110. It was offered for sale adaptable for varying wheels, gears, and brakes.
Chris Boardman again established British prestige in International cycling when he dominated the 4000 meter pursuit in the Barcelona Olympic Games of 1992.He went on to take further records .His success was in part attributed to the high tech specification – design and materials of the aerofoil section composite monococque.
Its believed that Boardman rode the 110 in the 1994 Tour de France and later won gold medals at the Cycling World Championship.
He is known for the “Superman” riding position that has allowed him to achieve a CdA of .1838.
It’s believed he is now Head of R&D for the British Cycling Team. He also has a range of bikes including the Boardman Road Team Bike. [8.25kg. Approx.]
The Lotus 108 or Olympic Pursuit bike: Brief specification
Frame: composite carbon fibre with Kevlar and foam aerofoil section monocoque.
Transmission: Steel/ titanium fixed wheel and titanium handlebars. Gearing to suit rider and or event.
Front “Fork”: Carbon fibre mono-blade with aerofoil cross-section.
Wheels F&R: Mavic composite rim with aero-spokes/ disk.
Measurements: length 64”, width 16”, height 39”, wheelbase 38”
Weight: 9kg -20lbs- [estimated] some sources suggest 21.5lbs
The Lotus 110 Sport Bike/ Time Trial: Brief Specification
Frame: composite carbon-fibre/epoxy monocoque with aerofoil cross-section
Transmission: multi –gear derailleur
Fork: Front and rear wishbone type, with aerofoil cross-section.
Wheels F&R: Mavic on some models with blade “spoke” conctruction with aerofoil cross –section
BrakesF&R: Mavic side pull
Measurements: Length 62”, width 18”, height 40”[variable] wheelbase 39”
Weight: estimated 17.5-21.8lbs depending on specification/ components.
[The modern equivalent machine might weigh 14.5lbs]
Its believed the following prices applied.
1992 Lotus 108 Pursuit £15,000
1993 Lotus 110 Sport bike £1650+
Human Powered Vehicles [HPV]
Offer the opportunity for:
Better handling agility Stability, weight distribution
Safety, weight distribution, centre of gravity
Relative weather protection
Sustainability: HPV under certain city riding or short distances might compete with the car for convenience, whilst being non-polluting using minimum of materials in construction and life span. Energy input in non –renewable.
Most HPV are recumbent and with their smaller frontal area improve aerodynamics and hence efficiency. They lend them selves to enclosing fairings
Sociable Tandem [Twike] [Alusuisse-Lonza Services AG] optional motor.
Windcheetah SL Mk.VI “Speedy” tricycle [Mike Burrows]
Peer Gynt II
Sunlight and electricity complementary power source assistance.
The Proposed CCM&EC
The proposed museum believes that commercial considerations can be both necessary and complementary with an educational programme.
For these reasons our business plan includes provision for promoting products that are consistent with the Chapman methodology of mechanical efficiency and sustainability.
Written into our plan are extensive proposals for cycling: racing/ competition, machines, components. Accessories, history and supporting books and related literature.
Colin Chapman/Lotus are most readily identified with sports cars and motor sport. This risks losing sight of the underlying philosophy and adherence to mechanical efficiency through lightweight. The achievements in motor sport were primarily the consequence of a relentless reductionism. Chapman just before he died was looking and evaluating the potential of micro lights perhaps not exclusively because of their green credential but this was a direct benefit of the design and construction. Whenever Lotus undertook consulting or direct design allied with their competitive drive to win produced machines of extra ordinary aesthetic and extreme simplification and weight reduction.
The A&R is proud to feature the sports bikes as a representation of one of the finest examples of performance with applied sustainable opportunities and outcomes. As a consequence form and function are in perfect harmony and expression.
Mike Burrows and R.Ballantine “Bicycle Design: The Search for the Perfect Machine” Snowbooks Ltd; 2008
Michael Embacher and Paul Smith “Cyclepedia”A Tour of Iconic Bicycle Design” Thames &Hudson 2011
The Lotus Book*
Richards’ Ultimate Bicycle Book. Dorling Kindersley 1995
Pryor Dodge “The Bicycle” 1996 Flammarion.