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Reinventing the Wheel:
Pushing the limits in high performance bike design

By Steven MacGregor

"Every time I see an adult on a bicycle, I no longer despair for the future
of the human race"
—H. G. Wells

Introduction
¡¡¡¡KKKRRRAAAAACCCCKKK!!!! — that familiar push of the gears to the 53-12. I jumped out of the saddle and blasted away from the pack. One or two of the others entered the first of their Ks as I finished mine, but that was all I needed. For 8 seconds it was head down and a heavy pull on the legs as my cadence increased from around 60 to 120 revolutions per minute. I threw a quick glance under my right armpit—they still didn't have my wheel and I noticed the grimaces on their faces as they experienced the pull towards that high tempo. It was so effortless and I felt that I had gears left—I looked down at the sprocket but sure enough, the chain was sitting on the lowest level. It's then you hear the sound—the traffic, the groans, the wind—all disappear, and notice only a faint whirring, like the wing-flap of a humming bird may sound. And you do nothing; you're producing 500W of power, spinning your legs twice per second, travelling at over 35mph...but you do nothing, apart from listen to that sound ($2000 dollars of Italian-made carbon and steel singing a sweet song, operating at 98,6%1 efficiency). But it doesn't last, 'cause as soon as you hear it, you know there's only a few seconds left before the world comes crashing in, and your legs start falling from that high stroke and begin to protest the power they're being asked to produce. But the line is there, and so close. You feel the presence of other riders on all sides, and then you see front wheels, and then a head...that front wheel inching ever closer. You strain, and lunge—that sound a distant memory, and the line is yours.

Hey, it was only a Thursday night ride with the pack in Girona, and the line was the sign for the town limit, but that feeling is what it's all about.

In athletics you can't imagine track runners being forced to wear the original waffle shoe as worn by Steve Prefontaine in the formative years of Nike, yet this is exactly the case in cycling with the World Hour Record.

Slow and Steady
With the phenomenal achievements of 7-time Tour de France winner Lance Armstrong, cycling has never enjoyed a higher profile in the US, and indeed, worldwide. Pushing the limits of the human body to ride over Alpine and Pyrenean mountains—producing up to 1000W, then riding at over 50km/h in team time-trials2—has been enabled in recent years by a similar pushing of the design limits of the riders' bicycles themselves.

But bicycle design is a funny thing. For all intents and purposes, its main design has remained unchanged for over 5 decades. Yet an evolutionary design approach, through various iterations, has led a continual search for optimum solutions within the same core design; though the formal bones of the bicycle have remained the same, several significant changes have come through material and mechanical innovation. It's been slow and it's been gradual, but these changes now represent the improvements necessary to help riders squeeze that little bit extra out of the human body.

If you can't enter a competition with a new bike design, manufacturers are unlikely to develop it. This means that most changes are manifested on a cosmetic level.

Inventing the Wheel
Although Da Vinci sketches of a bicycle-like product date back to 1493 (see fig. 1 below), the German inventor Karl von Drais is widely credited with its creation in 1818. The first pedaled bicycle was then produced by Scottish blacksmith Kirkpatrick Macmillan in 1839 (see figure 2 below). However, two major innovations towards the end of the 19th century gave us the bicycle as we know it today. The Rover Cycle Company in England was one of the first to produce bikes with the new chain drive mechanism—a safer design attached to the rear wheel, as opposed to the previous direct drive mechanisms on a large front wheel. This was followed in the late 1880s with the invention of the rubber pneumatic tire, by another Scotsman, John Dunlop. These tires allowed a more comfortable ride and liberated the bicycle from its early "bone-shaker" tag, so-called due to the jolting ride of previous solid tires negotiating the poor road conditions of that era.


Fig.1: The Da Vinci sketch from 1493
Fig.2: Bicycle with MacMillan pedals (the more efficient method of pedals with cranks would subsequently be developed in France)
Fig.3: Bicycling in the 1870s lack of a chain drive mechanism necessitated direct drive on a large front wheel

At this point, time essentially stops; the bicycle has had the same core design principle for nearly 120 years, although both complexity and sophistication have nevertheless increased in that period.


The Whole and its Parts
It is useful to view the present-day bike design 'system' as analogous to a computer system. Think of the bike frame as the computer housing (Specialized and Airborne in the US, Orbea in Spain). Here, the operating system is the derailleur (a straight fight between Italian Campagnolo and Japanese Shimano), and the processor is the wheels (Kysirium and US HED). But then you have the whole range of extra peripherals: the pedals, saddles, seatposts, handlebars, chains, cassettes, chainwheels, bottom brackets, brakes, hubs, stems, headsets, and forks. These are all highly specialized, precision-engineered components that aim to improve efficiency at each part of the system, and each has given rise to a host of specialized component companies.

And this is a critical point: Cycling is an oft-underestimated, brutal sport, filled with periods of pain and exhaustion. But better bike design has resulted in rendering this pain more bearable, and made those high points last a few seconds longer. The key is in making your body an extension of the bike— for as long as possible.

As a result, where efficiency was previously lost at the human-bike interface—such as pedaling (now clipless pedals instead of stirrups), gears (now able to change gearing without necessitating that the rider reduce pedal pressure) and brakes (around 50% less force required to operate brakes than in the past)—all of these incremental and separate improvements have, cumulatively, served to help blur the line between where the bike ends and the rider begins. And this is a critical point: Cycling is an oft-underestimated, brutal sport, filled with periods of pain and exhaustion. But better bike design has resulted in rendering this pain more bearable, and made those high points last a few seconds longer. The key is in making your body an extension of the bike—for as long as possible.


The UCI Stranglehold
Indeed, the richness of all these evolutionary changes at the component level have resulted in a cumulative improvement in performance at least equal to any revolutionary design changes that would have occurred on the overall bike system level. Examining the past 30 years in more detail provides an interesting comparison. In athletics, you can't imagine track runners being forced to wear the original waffle shoe as worn by Steve Prefontaine in the formative years of Nike (arguably, it would make very little difference), yet this is exactly the case in cycling with the World Hour Record—the blue riband of the time-trialing cycling world—where cyclists aim to travel the longest distance possible in 1 hour (see http://en.wikipedia.org/wiki/Hour_record for an excellent summary).


Fig.5: Eddie Merckx setting the hour record in Mexico City 1972; just the 'animal' and the bike
Fig.6: Lance Armstrong on his 2005 Tour de France time-trial machine, the Trek TTX

Given bike design improvements in the past 30 years, the UCI (Union Cicliste International, the worldwide governing body) reset the record and bike set-up to that used by the great Eddie 'The Animal' Mercx in 1972. All records posted after this date—using increasingly sophisticated bike set-ups—were deleted from this newly termed 'athletes record.' Under the new rules, and in line with the 1972 record, time-trial bars and disc and tri-spoke wheels are banned, while other geometric constraints insure that no further aerodynamic advantage is gained over Merckx's Mexico mark. This was recently bettered by Czech Ondré Sosenka (as reported by Ed Hood [1]) who rode 49.7 km, almost 31 miles, bettering Merckx's mark by 2.7km, on the 333m indoor Krylastskoye track in Moscow. Witnessed by only 40 people, Sosenka rode a Dedacciai-carbon Moser weighing 9.8 kilos. The giant Czech—almost 2 meters tall—had to ride a radical frame set-up in order to stay within UCI restrictions: the saddle was jacked up considerably (resulting in a 'fly-through' on the seat-tube of approximately 18"), with Sosenska riding with almost vertically-straight arms...a radical departure from conventional tri-bars-influenced aerodynamic positions.

The hour record—up until the restrictions implemented by the UCI in the form of the Athletes Record—provided a test-bed for several pioneers as they sought to push the boundaries of bicycle design. The early- to mid-90s saw a see-saw battle between Englishman Chris Boardman and 'Flying Scot' Graeme Obree (http://en.wikipedia.org/wiki/Graeme_Obree). In contrast to Boardman's high-tech, high-budget approach, Obree built his own racing steeds, at times using spare parts from washing machines. He also pioneered subsequently UCI-banned riding positions, including the 'tuck' and 'superman.'


Fig.7: Graeme Obree in the subsequently banned tuck riding position
Fig.8: Moser's revolutionary 1984 Hour Record Bicycle
Fig.9: An unsuccessful attempt from the following year

The man who made the biggest impact, however, was the Italian Francesco Moser. Moser's influence revolutionized mainstream road-racing. He was the first man to better Merckx's 1972 record, using a bicycle with a sloping down tube and larger diameter back wheel. Both wheels were disc wheels (to minimize air drag), while the conventional racing handlebars were replaced by simple bars which curved upwards at the ends—enabling a more aerodynamic position and providing the pre-cursor for tri-bars. Although not all design changes were able to be adopted by the UCI-controlled racing scene, the basic philosophy of Moser's approach facilitated a change in the mind-set of the professional and wider road racing body. Racers began to think more about how to minimize weight for mountain stages and improve aerodynamic efficiency in time trials.

But the UCI's influence reaches far beyond record attempts, and into the world of design and manufacture proper. A series of stringent technical regulations have minimized the proliferation of revolutionary design concepts over the years. These technical regulations include tight rules regarding sizing, geometrical relationships between different parts of the bike, and tube shapes. Competition cycling sets the trends for the overall market—providing exposure as well as a large percentage of sales—so if you can't enter a competition with a new bike design, manufacturers are unlikely to develop it. This means that most changes are manifested on a cosmetic level, though there are one or two exceptions: Sloping top tubes have recently been adopted by many manufacturers after the UCI relented on the original GIANT compact frame concept, while frame weight minimums are under increasing pressure. (Several manufacturers are likely to affect a re-think of the UCI year 2000 imposed minimum weight of 6.8kg, or 14.96lbs.)

Whereas wheels represent an often overestimated design improvement for racing bike performance chains could be viewed as the exact opposite.

Innovations Nonetheless
Use of carbon fiber has been the biggest innovation during the past several years, and has facilitated significant improvements in the weight and stiffness of the bike. Developed by the United States Air Force in 1960s, the use of carbon in bicycles has increased several-fold in only the past 3-5 years. Carbon has exceptional weight-to-stiffness properties, so newer frames flex less, making them more efficient and requiring less energy to propel them. On the downside, this increased stiffness can provide for a less comfortable ride, and can result in greater fatigue after several hours in the saddle. (The weight-reduction has been so significant, in fact, that a recent Specialized carbon bicycle had to attach a spanner to comply with minimum weight restrictions in the Tour de France!) The increased uptake of carbon for the bike frame was quickly followed by other components, so that now handlebars, seat posts, bottle cages and wheels all have carbon versions. With the winding manufacturing technique able to produce previously unattainable shapes, both more aesthetically pleasing and ergonomically and aerodynamically sound forms are possible.


Fig.10: The complete Campagnolo Chorus derailleur system


Fig.11 & 12: The 2005 Campagnolo Record rear derailleur, and an older, dissembled version

The operating system for the bike is the groupset which includes several simple yet elegant design features. Ergo levers allow simple, comfortable and safe gear-changes. Profiled sprockets improve efficiency and better power transmission through the chain, while new rear derailleurs are manufactured almost completely in carbon and steel with titanium screws. Dominated by the Italian Campagnolo and Japanese Shimano, the present-day gearing system is 10-speed with either double or triple cogs. Other components include the front and rear derailleurs, front and rear hubs, ergolevers, sprockets, cranks, bottom bracket, seatpost, headset, brakes and chain.


Fig.13: Campagnolo Record ergo-levers
Fig.14: HED3 tri-spoke carbon wheel from HED
Fig.15: Stirrups are a tight fit, but be prepared to cut the blood flow to your toes! (Not to mention the impossibility of removing your feet during a fall)

Ergo levers make gear changes much easier, so riders are more likely to use their gears to better effect—thus saving energy. Until 1992, gear shifters were located on the main frame of the bike, and required the removal of one's hands from the handlebars. These improvements in comfort and safety are complemented by improvements in the braking system. Previous versions with protruding brake cables required a minimum of 50% more grip strength to operate them (resulting in many veteran cyclists with huge hands!). Ergonomic lever hoods now allow the hand to comfortably stay in a safe position at all times, enabling full-strength braking with hands placed on top. Other design improvements include following value engineering best practices (as can be seen in the old Campagnolo rear derailleur in figure 12 above), and reducing the number of parts. Increasing modularity and interchangeability also helps with maintenance and repair— a frequent travail of the racing cyclist.

Wheels have also changed notably, mostly due to materials innovation. Carbon rims have resulted in stiffer wheels with fewer spokes needed to keep them 'true.' (This has also affected the weight considerably.) However, this is an oft-overestimated advantage when it comes to power generation and resultant acceleration: providing the weight of the bike remains constant, the energy saved by having a light set of wheels, compared to having, say, a light frame, makes an insignificant difference (of the order of 0.02%) to the total power required to accelerate the bike and rider3. Time-trial bikes often utilize rear-disk wheels and tri-spokes in an attempt to improve aerodynamic efficiency however, with the US manufacturer HED well-known for producing distinctive designs and beautiful carbon wheels (see figure 14).

Where wheels represent an often-overestimated design improvement for racing bike performance, chains can be viewed as the exact opposite. Improvements in chain development, including manufacturing quality and higher tolerances, have helped facilitate an almost perfect meshing with the rear cassette; rotation of the chain around the cassette now represents an almost perfect circle, rather than the older nonagonal relationship. Better-profiled sprockets are also key, and fit better with these new chains, which have much higher traversal flexibility to enable 'jumps' between several gear levels. The most significant practical improvement, however, is the ability to change gear with pedal pressure. Before—and especially with gear shifters placed on the main frame—one had to take most of the pressure off of the pedals, pull the lever (effectively over-changing), and then 'trim' the lever back a little to centre the chain. In the past, you picked your gear at the bottom of the hill and stuck with it; like-wise when sprinting. Out of the saddle 'jumps' are now the norm, and result in more exciting racing. Roller chains, with their superior wear-resistance, and ability to spread load across their width while maintaining flexibility, are the most efficient means of power transmission between two sprockets (evidenced by their usage on fast motorcycles). Together with high build quality and better-profiled sprockets, power transmission efficiency on road bicycles is extremely high.

Other examples of the trickle down from professional use to mass adoption—further demonstrating the influence of the elite ranks from the technical regulations of the UCI, to Hour Record pioneers like Francesco Moser and Graeme Obree—are the pedals and bars. Clipless pedals had existed for a number of years, but did not replace the conventional stirrups until after Bernard Hinault, 5-time Tour de France winner, used them in 1985. US Tour Champion Greg LeMond was another pioneer, using tri-bars to devastating effect in the final stage of the 1989 Tour. In an individual time-trial with finish on the Champs de Elysee, he came from behind to pip Laurent Fignon, sans tri-bars, by 8 seconds—the closest Tour finish in history.


Final Thoughts
Though the bicycle has retained the same core design principles for over 120 years, the overall design system has increased greatly in sophistication during the past 30 years. Though the actual "mechanics" of how the bicycle works haven't changed much, material and manufacturing innovations have helped to push the boundaries of human performance.

As in many fields, pioneers help to affect changes, with the most prolific design thinkers often those who are in the heat of the battle—in this case, professional cyclists. With ever-advancing technology, the future for bike design may not depend on what is possible, but rather what the UCI deem to be allowable. However, companies are growing increasingly tired of the UCI stranglehold. As stated recently by US manufacturer Specialized, "To stop innovating because we've approached or breached an arbitrary limit would be both counter to our desire for continuous improvement as well as a rather large business blunder." Only time will tell how this relationship will affect overall bicycle innovation. The boundaries of human performance will continue to be pushed back—how far will depend on who continues to reinvent the wheel.


Footnotes
1 John Hopkins University laboratory tests, 1999, Pedal Power Probe Shows Bicycles Waste Little Energy
2 Team Discovery Team-Time-Trial record Tour de France 2005 57.324 km/h over 67.5 km
3 Source: cyclingnews.com December 2005

References
[1] Ed Hood, Sosenskas Hour http://www.braveheartfund.com
[2] William P. Ancker, Velocity and the Velocipede
[3] Pedro Delgado homepage: http://www.marca.com/perico/

Acknowledgements
I'd like to thank contributors to the Braveheart fund forum for their insights into bike design. The Braveheart Fund supports the development of young Scottish cyclists. Thanks also to Martin Coopland at www.batesbicycles.com.


Steven MacGregor is a Scot based in the Catalan region of Spain. He holds a PhD in Engineering Design (on global design teams, available at design4distribution.com) from the University of Strathclyde in Glasgow and is now a self-employed Spanish 'autonomo' providing contracted innovation services for Universities, private enterprises and government bodies (spmacg.net). He teaches at the University of Girona and ETEO School of Business in the Basque Country. Steven is also an international Duathlete (run-bike-run) and directs a sports tours company in Girona (macstrongtours.co.uk), the previous Tour de France preparation base of a certain Mr. Armstrong.