Readers may know that last year, I addressed how carbon nanotube technology had been seeping into the bicycling scene. While by themselves, the properties are very remarkable, the issue we all want to sort out is, how much is the end product we care about - the bicycle frame - improved by using such tech?
Some readers in that article held the view that this technology is an "April Fool's joke" on the consumer, that the change in finished properties in the frame with nanotube reinforcement is extremely small and not worth it considering the increases in cost. Is this just a "feel good" marketing ploy from the cycling industry? Should it have prevented failures such as this one?
Today's article below is borrowed from one of the writings of Dexter Johnson, who is an IEEE technical blogger writing for Nanoclast. Here, he's posing the question of what nanotube reinforced bicycle frames really have to offer in terms of cost-benefit and also explores the different buzz words seen in bicycle marketing literature. Do they mean anything at all?
Enjoy the read and let me know what you think.
Nanotechnology And The Bicycle
Dexter Johnson, IEEE September 9, 2009
At a conference that I had put the program together for a few years back, a speaker during his presentation suggested that maybe he would supply some carbon nanotubes to a bicycle manufacturer and have Lance Armstrong ride the bike in the Tour de France. What a great marketing idea, he thought out loud.
Being an avid cyclist and an even more avid fan of cycling, I explained to him that the professional cycling federation had put a weight limit on bicycles and that maybe there was not much to be gained in pursuing this marketing avenue.
How wrong I was. Since then, which I believe was around 2005, I have become aware of at least three high-end bicycles that employ some kind of nanoparticle in the frame.
The three that I know of are Spanish-based BH Bicycles, Swiss-based BMC and most recently I’ve discovered Italian-based Pinarello has gotten on the nano bandwagon.
What does the nanotech actually do for these bikes other than to raise their asking price slightly north of a new economy car? Well, it’s hard to say except by taking a look at their marketing copy.
Let’s start with the BH G4 bike. Here the marketing copy reads: “BH achieves this magical blend of low-weight, great ride and toughness using Nanotechnology resins.”
“Nanotechnology resins”? After reading the rest it appears what they mean is that they are using carbon nanotubes as a filler material between the carbon fibers. Despite the rather breathless description of how carbon nanotubes “have a strength-to-weight ratio orders of magnitude greater than steel”, they never quite get around to saying whether the CNT-enabled resins make the carbon fiber bicycle any stronger or lighter than any other run-of-the-mill resin.
BMC it turns out is using carbon nanotubes in exactly the same way as BH (not really a surprise to be honest). But BMC does manage to say that the material matrix that is developed using these carbon nanotubes is 20% stronger for practically the same weight. I am a little concerned with the usage of the phrase “practically the same weight”. And for that matter what does “stronger” mean?
Pinarello appears to be much more discrete about their foray into nanomaterials, but they do manage to say the following: “the exclusive 60HM1K carbon by Torayca® with Nanoalloy™ that prevents sudden breakage.”
Wow, now we’ve got a nanoalloy (and it’s trademarked)! From what I have been able to piece together about the “Nanoalloy™” from the bicycle trade press is that:
“Nanoalloy… disperses nanoscale elastomers between the carbon fibers. These elastomers have the ability to absorb impacts and prevent the propagation of cracks as they occur.” The result: Pinarello claims the Dogma frame weighs about 860 grams, 40 grams less than the Prince but is 23 percent more resistant to impacts."
Could this resistance to impacts that Pinarello describes be the same “stronger” that BMC offers up?
Is there anything to all of this nano talk in bicycles other than a cool marketing angle? Impossible to say outside of conducting some real experiments, and it’s hard to imagine anyone being that interested to bother.
Now if we can develop a material that would be perfect for the rigors of a bicycle frame by using a material by design method and then build the material and the frame atom-by-atom then I might pay a premium price for it. Will I still be able to ride a bike by then? Stay tuned.
Last week, I had the honor to chat over the phone with Prof. David Gordon Wilson of MIT. It was an initiative I took as something told me I had to find out how he's doing and what he's up to these days, at the same time capturing some of his views and experiences on cycling, past and present.
Prof. Wilson is to the recumbent HPV as perhaps Gary Fisher is to mountain biking. A keen hiker and bicyclist, he was a former president of the International Human Powered Vehicle Association, and was editor of its journal Human Power from 1984 - 2002. During this time, he also taught engineering design, turbo-machinery and heat exchanger design to students at MIT. One of the many feathers in his cap was the Avatar-2000, a recumbent bicycle he co-designed with Fomac Inc. It won the non-UCI world bicycle speed record twice, 1982-1983.
While these things may not be quite familiar to people who don't know him well, his name is most popularly associated with the seminal text Bicycling Science, a book that acquired an almost cult like status after it was published by MIT Press in 1974. Flushing away previously held myth and folklore, it shed light into the physics and engineering of bicycles and steered the way for better technical understanding of the subject. This, together with some other supplementing events, stamped the official authority of bicycle 'guru-ship' on him.
Today, the book has undergone 3 revisions and is still studied and quoted from by cyclists and enthusiasts world over. I personally remember the occasions when I would borrow this book from my college library and sit on it for days. So much was my interest to read and understand this text that I got fined on several occasions by the library for not honoring my return dates (sheepish grin).
Prof. Wilson was born in 1928 in Warwickshire, England - a long way in the shadow of the first World War, and just a year or two after John Logie Baird had given the first public demo of the television and English women over 21 years of age had been enfranchised (Source). Ever since his childhood, he loved riding a bicycle and made it an immediate hobby, even prime to that of his desire of being a pilot.
In a chapter of his upcoming Memoirs, he writes that it was on his ninth birthday in February 1937, that he was presented for the first time with a Hercules single speed boy's bicycle by his father. By the time he was 12, he was riding a 3 speed bike with 26 inch wheels and handlebars that could be reversed to the semi-dropped position. By today's standards, it would easily be called a 'clunker', but David looked forward to every journey on that machine. In fact, he was to ride it for the rest of his stay in Britain for almost a quarter century.
WWII came and went and despite having some difficult personal experiences to go through, he would be single handedly organizing bicycle tours across the country with his friends while studying at Bishop Vesey's Grammar School in Sutton Coldfield. After graduation, he was encouraged to take up mechanical engineering at the University of Birmingham. This was a course of action that he fell back on after being turned down for armed service in the Royal Navy due to the demobilization (Memoirs manuscript, Chapter 3).
He first crossed the Atlantic in 1953 after a PhD from University of Nottingham, working his way in the engine room of a cargo boat on the Glasgow-Montreal run. In 1955, he was awarded a post-doctoral Commonwealth-Fund fellowship for study and research at MIT and Harvard. He worked as a turbine engineer at Boeing. After returning to work in Britain in the gas-turbine industry, he taught for two years in Nigeria and worked briefly with the VSOs (the British precursor of the US Peace Corps) in the Cameroons. For six years before joining the MIT faculty in 1966, he was Technical Director and Vice President of Northern Research and Engineering Corporation (NREC) in London and in Massachusetts.
It was there while working for NREC that he got the bright idea of sponsoring a worldwide bicycle design competition. It worried him as he discovered that as opposed to England, fewer adults were actually riding bicycles in the US. From many unfavorable personal experiences, he was also concerned that there were glaring deficiencies in modern bicycles that made using them more dangerous than they should have been.
So a competition to design a better bike that would encourage more cycling was proposed. It was widely publicized in the magazine Engineering from 1967-1969 and on April 11, 1969 the winning design was picked. It would be a recumbent bicycle designed by W. Lydiard which, to David, would spur a deep interest in recumbent design. He designed one in 1970 and took it to MIT to show it to his students, after which he decided to ride it home through Cambridge. To his amazement, people cheered him as he went past. The comfort, speed and safety benefits of recumbents were a revelation to him and he openly supported the movement in his teachings, letters and interviews. This interest in human powered vehicles, together with the book Bicycling Science that he had published soon after, would lift him to the status of a bicycle guru.
As if that wasn't enough to keep him busy, he also worked as a consultant to Abiomed Inc. where he designed the centrifugal pump used in Abiocor, the world's first artificial heart. In 2001 a group of MIT people ("Ignite") joined him to form Wilson TurboPower Inc., a startup company part-owned by MIT, with the aim of developing and producing very-high-efficiency regenerative heat exchangers and gas turbines. Dave was chair of the board of Common Cause, Massachusetts, in 2003, a group trying to reintroduce democracy into Massachusetts politics. He also co-founded and took leadership of MASH (Massachusetts Action on Smoking and Health), a group that worked for nonsmokers' rights.
He happened to even tell me the following :
"I used to be a beekeeper and worked for a bee farmer in Perry, Iowa a while ago."
David has held a number of respected positions, everything from an engineer at Boeing, gas-turbine designer at Ruston & Hornsby (UK), to editor of Human Power Journal, Chair of the IAP Policy Committee, VP of NREC, to currently Emeritus Professor at MIT, and President and CTO of Wilson TurboPower Inc. See here for more on his research interests and honorary titles accumulated over the years.
In the next couple in installments of this series, I will present to you some of the details of the conversation I had with him. Everything from Bicycling Science to his views on the current energy crisis. So stay buzzed!
Some of you may have heard that Naked Bicycles, owned by the Canadian speed demon Sam Whittingham, won the 2009 People's Choice Award at the North American Hand Made Bicycle Show early this year. This is the second year in a row that he's won an award at the show. The Canadian "A" channel had a piece on that story :
In case you don't know who Sam is, you can read a little about his background in bicycle design and his dabs over the years at setting speed records, recently one of which was a little over 1/9th the speed of sound. He is considered to be the fastest cyclist in the world as far as HPV's and short, flat distances are concerned.
However, his real motivation was to explore what a mountain bike would have looked or evolved into in the 1930's, had it first been built in the 1920's. That is a pretty interesting thought process considering that the mountain biking movement didn't start until the 1960's with the 'clunkers' of California. In essence, I guess he wanted to take his audience back to the age of Frank Sinatra and show what folks would mountain bike with then. As he told Velo Media, he wanted to 'throw everything over the top in a MTB and see what happens'.
Elsewhere on his blog, he stated somewhat differently :
"The idea with this one was to take the lines and modern technology of a modern rig and give it some old-skool building charm. I was delighted to see that many other builders where also not afraid to step outside of 1975 and let there mind wander a bit."
“I wanted to take the modern technology of a mountain bike, the lines, 5 inches of travel, 29-inch wheels, but put it together in a very non-plastic way. Let’s take a nice modern mountain bike, but put some soul in it.”
SIX WEEKS AND 18,000 DOLLARS LATER...
Courtesy : Zack Vestal
From the above ideas, a mere six weeks of hard work and a hellova lot of cash resulted in the Cherry Bomb, a gracefully curvy lugged steel, single speed, dual suspension MTB with 29" wheels made of classic beech rims and a maple wood seatpost. Lacquered wood and nickel finishing was plenty. Its a medly of both old and modern design elements.
The curvy frame has a lugged design, which was polished and painted metallic red. The lugs were nickel plated.
The seatpost, used to represent Canada, was made from a piece of firewood, as Sam reported, which he split and turned.
The dual suspension has 5" of full travel. An interesting feature here is that the main upper and lower suspension pivot uses modified FSA headsets, which are designed to take pivoting forces and can be replaced if worn out. The headsets use angular contact bearings and are adjustable for bearing pre-load.
A Campagnolo down tube shifter was grafted onto a Fox Shox lockout lever. The linkages, which activate the shock, were fully curved, mitered and welded, and then nickel plated to a super shine. Nickel plating, as I said before, is used very liberally in this design, including for all of the lugs, suspension pivot and rear shock mounts, and even the entire rear triangle.
Then comes the "beefy" pedals which, beautiful as they look, were decorated with a mother of pearl inlay for the ultimate touch. There is plenty of wood here, an aluminum platform on top and what looks to be 'spikes' for grip (not sure if that was intentional). Sam likes to call them "Shin Burgers". Hey, who wouldn't want to stomp on these, provided they're given steel toed boots? (smirk)
The handlebars were made out of ash wood, turned down to fit with the one piece Al handlebar-stem combo and wrapped with leather grips. A Chris King In-Set headset was used in the front end for steering.
Another unique feature are eccentric dropouts which have a concentric pivot for clamping the rear wheel. This design also helps adjust the tension in the chain. While bikes like the new belt driven Treks use them, such designs are a staple for Sam's bikes. I pieced together a small section of a video from Veloo Media where Sam explains at the show how these dropouts work.
But I felt the cake of the entire design were the wooden rims, a big step back if you will from our modern world of varied alloys, carbon fiber composites and other unobtanium. These rims were obtained from Wheel Fanatyk, a U.S distributor for Cerchi Ghisallo, the original Italian producer.
Let's talk a little about the design and manufacturing of these wooden rims.
DESIGN AND MANUFACTURE OF WOODEN RIMS
The wooden rims made of beech were provided by FSA employee Ric Hjertberg, the man behind Wheel Fanatyk, a workshop that distributes these rims for Cerchi Ghisallo.
Cerchi Ghisallo produces wooden rims, mudguards, chaincases, and beechwood packs and carry racks.
Rims like these were the bread and butter of bicycle racing for over seventy years and it made sense to rig the Cherry Bomb with the classic, lively ride of the yesteryear. However, rim brakes introduce the challenge of rim wear due to grit sticking onto the brake pads, although wood's co-efficient of friction with such brakes are superior in dry riding, as claimed by Ric here.Traditional brake pads would also melt due to the localized heat produced during braking. So it was decided that the Cherry Bomb would feature disc brakes for practicality and safety.
Ric has interesting things to teach us. I thank him for this writeup, where he talks in detail about the functioning and other design considerations for wooden rims.
"To understand how a wood rim functions, we need to talk about density and the stiffness of shapes and materials. A bicycle rim resists bending according to the stiffness of the given material and shape. However, material near the rim's exterior does most of the work. Why? When the rim bends, this exterior undergoes the greatest deformation. For example, with a bend to the left, compression is felt on the left and tension on the right. These forces are greatest on the surface, furthest from the rim centerline. As it bends, the magnitudes of compression and stretching are greatest on the surface and this area puts up the greatest resistance. If the rim were solid, material in the center would barely detect the bending. For every degree of bend, internal deformation is smaller than that on the surface.
Wood is much lighter than metals or composites, and this low density is what it leverages as a wheel rim. Density (g/cm3)
carbon fiber = 1.7
aluminum = 2.7
wood (beech) = .7
Because wood is so light, its resistance to bending is necessarily less than metals. Compared to the other materials, wood needs more frequent spoke support. So, we use traditional spoke numbers like 32 and 36 per wheel. In fact, wood's long reign as premier high performance rim is a major reason for these particular spoke counts. Even three decades after switching to aluminum alloys wheel makers retained these numbers. In the face of aerodynamic evidence, spoke numbers have come down dramatically. However, research shows that the wind resistance of larger spoke numbers only becomes a liability at high speeds rare outside of competition.
So, given more spoke support, what kind of wheel does this solid but very light material make? First, the lower spoke tensions that wood prefers allow it to move around more. This additional degree of motion allows it to absorb shock, to attenuate the vibrations of the road; the same as a lower pressure tire. But the actual deflection of a wood rim during riding is tiny, so the bicycle's quickness is not impaired. What seems to disappear are the higher frequency vibrations of pavement that can tire the body over time and make joints ache. An aluminum rim, built to lower tension, would also move around. Unfortunately, aluminum does not absorb energy to the degree of other materials like steel, wood or composites. So the comfort benefit would be small.
In addition to shock absorption, wood is harder to dent. Its low density means that a pot hole will create only local damage: a nick rather than a generalized dent that might interfere with braking. So, wood rims are legendary for resisting dents; a valuable asset in a world of poorly paved roads. One further advantage is the heat resistance of wood. Rim braking dumps large amounts of heat into the brake caliper and rim, in order to slow the vehicle. Aluminum rims eagerly accept this heat which, when excessive, can melt the tire or tire cement, causing failures. Wood rims refuse to accept this heat preferring, instead, to burn superficially at their surface. A wood rim pushed to braking extremes will create a barely detectable burning odor, but its tires remain cool. The flip side of this tendency is higher heat that brake pads see. Unable to hand off the heat to the wood rim, traditional brake pads will melt on wood. This characteristic can be managed.
On first glance, the thermal characteristics of wood seem similar to carbon fiber: neither readily accepting heat. However, the similarity is superficial. A carbon rim accepts heat slowly, a wood rim nearly not at all. During a demanding descent, brake pads can feel overheated with either material, but slowly and relentlessly the carbon rim becomes hotter and hotter. It dissipates the heat too slowly, so can reach melting temperatures. Wood, on the other hand, might burn a bit on the surface but as a bicycle rim will not reach elevated temperatures. Bottom line, no rim material is ideal for braking. Aluminum or carbon, wood or magnesium, dealing with thousands of watts and trying to protect an inflated tire is a tough and hazardous job."
Ric also explains how wooden rims are historically made. It is an expensive and involved process that takes time. First, thin and specially aged beech strips are soaked prior to shaping, and then coated with a 2-part epoxy to be bent into a spiral wound, hoop shape. Between each strip is a layer of cotton cloth. The spiral hoops and basic rim shape are securely glued and then fly cut on a horizontal routing machine, several cuts after which the rim assumes its basic shape. The rim is then precisely drilled to make spoke nipple holes, after which it is carefully sanded with many coats of marine epoxy.
From Ric's Ebay Page For Wooden Rims : This beautiful wood rim is artisan made by Antonio Cermenati in Magreglio, Italy. It is constructed of aged Slovenian beech wood, assembled in thin laminations that are joined by 2-part epoxy in a proprietary process that the Cermenati's have been perfecting for over 60 years. The Sport rim is available in 700C, weighs about 560 g., has 32 spoke holes, is designed for clincher tires, and comes with a set of extra long nipples and shaped washers. This rim is sold for restoration and historic projects, however, such rims were ridden by athletes and adventurers on the World's most demanding terrain for nearly a century. Due to the individuality of handmade wood rims and the skills required of the wheelbuilder, we cannot warrant the performance of these rims. All we can guarantee is our vast experience in rim making and wheelbuilding, and our passion for excellence that extends to a commitment to work carefully with each customer. The Sport rim carries a pressure limit of 4.5 bar (65 psi) and its beads do not have the "hooks" which are common on today's high pressure rims. This design is the same as all clincher rims prior to the 1960's and carry a tire reliably as long as it is mounted carefully and pressure limits are observed. The "hookless" bead is, of course, universal for automotive and motorcycle rims. The third image is, incidentally, a daily commute bike, travelling 19 miles each way in Seattle (wearing fenders most of the year). The tire is a 700X38C IRC "Metro" tire. This bicycle uses disk brakes, although wood rims are normally used with caliper brakes. The disk brake is a nice touch, enabling the rims to retain their new appearance for many years. Wheels made with wood rims have an unmistakable liveliness and exceptional shock absorption plus, surprising strength and damage resistance. Their beauty is simply awesome. Bicycles are transformed into artistic, nearly magical objects. If you've had the treat of seeing a contemporary bicycle fitted with classic wood rims, you know exactly what we're describing.
Precise drilling of the finished wooden rim. More of the rim manufacturing pictures here.
I guess it is now pretty obvious how all the costs to make this bike added up to 18,000 dollars!
While it was a bike made to impress no doubt, what I was simply amazed with were some of the 'think outside the box' characteristics behind Sam's designs. Too often people are complaining that the bicycle has been around for 100+ years and that design has reached a plateau. Well, that plateau apparently came about because we're seeing the market saturated with the same nonsense year after year. Seriously, I could hear a sentimental ballad from sailors in the middle ages and still not get this bored.
One only needs to take a visit to bike expos such as NAHBS to see the floor teeming with hundreds of fresher ideas, or ideas brought to life from the past. Thanks to all the folks who put up a great show this year and to all the others behind the scenes who made this possible. You can read about all the other award winners and their bikes here.
We're increasingly seeing companies specializing in motor vehicle systems enter the cycling industry. One of the obvious perks of this trend is that some fresh ideas are being dragged along into the cycling scene! Only a few weeks back, I had posted in depth about an ex-McLaren engineer's 'Thixomolded' magnesium folding bike. That is a world's first. Click here to read if you missed it.
What is making wild news at the moment is the Factor 001 bike designed by one of the suppliers of racing systems to the motorsport world, UK based Beru f1 Systems. Beru specializes in advanced design and manufacturing facilites for vehicle wiring harnesses, tyre pressure monitoring systems, stress measurement and load cells, with electronics and composites also as part of their business.
The bike is to be displayed at the Science Museum in London. See here. New photos of the bike will be released soon. Blogs and websites are calling it the "Most Advanced Bicycle In The World". I can't blame them at this point, since here are some of the highlights of the design :
Multi-channel Electronics Package : Provides unique ergonometric data collection (science of human-machine interaction optimization), logging and analysis capabilities which can correlate biometric data from the rider. It also measures physical force data from the bike and environmental data. All this has been supposedly developed with feedback from professional athletes.
Carbon Ceramic Brakes : I quote them as saying that this affords "exact braking performance at any temperature".
Fully Integrated Structure : Using BERU f1systems’ Wire-in-Composite patented technology; load sensors, wiring, batteries, sensors, control cables and lines for the hydraulic braking system are all fully integrated into the composite during construction, to give a clean, uncluttered appearance to the bike.
Heart rate, GPS coordinates and torsional stresses on the frame among other data are displayed on a touchscreen panel built into the handlebars.
Wireless connectivity
Monocoque Composite Wheels : 8-spoke monocoque composite wheels deliver high lateral stiffness and robustness, for, I quote them - "everyday use".
Made To Measure Frame : Bespoke made-to-measure frame (to within 1mm). Twin-spar frame reduces sideways frame flex and preserves rider comfort. Complete bike will weigh in under 7kg.
All In-House Manufacturing : Almost all original parts and key components are designed and manufactured in-house from Formula One-grade materials.
Here's a view of their disc braking system :
Chain : And rear of the bike :
MY THOUGHTS :
1) Specialized, Scientific Tool : That this is a highly specialized, scientific bike is without doubt in my mind. All the fresh ideas coming out of this F1 company is good for the industry. It'll get people to put on their thinking caps to start competing in the market. But I don't feel it can become a mainstream design. Frankly, all this instrumentation could be overkill for most racing bicyclists. Unless you're really obsessed with numbers, most of us cyclists hardly have the time to spend as lab rats. So this design may only be focused on a small section of the market. 2) Cost : As if that's not enough, the $28,000 price tag will have you double checking your purchasing choice. I'm not sure why having an 'on board computer' is being touted here as a striking feature. Cycling computers are hardly a new phenomena. And SRM, Powertap and other measurement devices exist in the market that are far cheaper to integrate with an existing bike for measurement (heart rate & power). So I think the key to thinking about this bike is this : How much more efficient in your cycling will you become (as opposed to now) with a $28,000 fully tricked out scientific lab on wheels? And will you see tangible benefits in performance to actually have your investment sort of pay itself over time?
3) Not Designed For Mass Start Races : People are saying that the bike itself may appeal to professional and semi-professional athletes competing at the highest levels in cycling and other sports; as well as personal trainers, fitness camp organisers, and affluent fitness training enthusiasts. But hold on. One of the designers of the bike wrote anonymously on a popular cycling blog in 2007 :
"The Factor 001 is not designed for UCI sanctioned mass-start races - Just as a car such as a Bugatti Veyron isn't designed with FIA regulations in mind. So super-quick wheel changes take a back seat to having the best braking option. It is a fast road machine rather than a 'racing' bike. The frame 'architecture' was arrived at simply because it offers the best lateral stiffness with the least mass, not to fit with UCI regulations (which it wouldn't in any case - the press release shots don't show very much at this stage)."
The wheel changing issue is true. If you carefully observe the rear portion of the bike, the tire/wheel is partially enveloped by what seems like a groove, or channel in the seat tube. Seeing latest pictures of the bike from a different angle, the seat tube has a bifurcation into which a part of the wheel sits in. This design feature escapes me and it may be just for style, or aerodynamics, but it brings about its own issues. The design may not be compatible with tires wider than 23c which could preclude its flexibility to riding variety.
Note : The above picture is an image of the prototype
4) Manufacturer Expertise : The makers of the bike have been traditionally knee deep in the F1 scene, working with electronic monitoring systems and composites. They may know motor vehicles but they are new in the cycling scene. Whether they know a thing or two about what makes cyclists tick, issues relating to fit and comfort, and whether they possess the knowhow of designing a stable riding bike are really questions open in the air right now.
UPDATE March 13, 2009
Here's a BBC video of the launching of the bike at the Science Museum in London.
One of the key aerodynamic design variables for fairings and streamlined bodies is the Length to Width ratio(also called Aspect Ratio in some literature). There is an optimum length for a fairing intended to minimize the total drag on a body moving through the air. At low speeds (Reynolds number below about 100,000), the optimum ratio of the length of the fairing to its maximum width is about 5:1. If the fairing is made shorter, pressure drag will increase faster than the surface friction is reduced. Conversely, if the fairing is made longer, friction drag increases faster than pressure drag is reduced. The situation changes at high speed (Reynolds numbers above about 1 million). Turbulence at these speeds significantly increases friction drag relative to pressure drag, and optimum fairings are shorter.
An a example, the WW2 De Havilland Mosquito has an elongated tear drop shape profile and a length to width fuselage ratio of 6:1. This is to maximize the efficiency of flight and fluid flow in the Reynold's number regime encountered by the aircraft.
Last week, the UCI said that since 2010, they'll be enforcing their 3:1 length to width ratios for any extension or streamlining of a section of a competing bicycle, be it aerobars, seatposts, crankarms, frames, or forks.
I totally welcome the enforcement of this rule by the UCI. You might think in a different way. But I say we shouldn't want bicycles looking like aircrafts, at least in the competition arena. As beautiful as they might be, that'll be a silly thing in sport, won't it? If someone has to introduce such extreme aids to empower themselves in pedaling, how do you differentiate between technological prowess and their true potential as a rider? I think this thought process is best stated through UCI's own 'Preamble' for bicycles :
"The bicycle shall comply with the spirit and principle of cycling as a sport. The spirit presupposes that cyclists will compete in competitions on an equal footing. The principle asserts the primacy of man over machine."
Hence, it is nice to have a governing body overlook these matters, or soon we would have bicycles looking so aerodynamically morphed that when they're ridden, the lift force will be so great that they'll take off no lesser than airplanes. For safety, bicycle designers would incorporate into them cockpits, oxygen systems and ejection seats. And that, I fear, will be the new doping in cycling.
It is interesting that today, there are a variety of aero forks that go over this 3:1 rule. For a few examples, check out this table compiled by BikeTechReview.
So does this mean that these forks in question are now UCI illegal since 2010? I certainly can't answer that 100%, but looking at the way UCI wants to enforce this rule, it seems very likely that these forks won't be accepted in competition unless some kind of exception is made (one could tell the UCI, oh please excuse me, my ratios are still very close to your limit, see?)
Lets keep this sport unadultered, pure and true to its spirit. No more BS. Primacy of man over machine, not the other way round.
The following article requires a coffee intensity of 9.0/10
Word has it that that GoCycle electric bike, first seen at the Teipei Cycle Show last year, was just officially launched early this week by UK based Karbon Kinetics of London. The wow factor is that it is the first bicycle in history with a frame set and wheels that are injection moulded in magnesium. It won top awards at Teipei, including one for Best Innovation.
The bike is the brainchild of an ex-McLaren engineer named Richard Thorpe, founder of Karbon Kinetics. Thorpe remarks that he was pulled into this idea after his total dissatisfaction with traditional bike design. He doesn't say specifically what he was dissatisfied about (any comments on that, Rich?)
Since GoCycle designed the bike but its core specialization does not include the manufacturing processes required, UK teams have been working on the mechanical parts of the bike while the magnesium frame is being manufactured by a Canadian firm using a unique process called Thixomoulding (see below). Finally, it is assembled by Ideal Bicycle Co of Taiwan. However, there is word that production facilities are now being UK-based to better serve customer demand.
MAGNESIUM WITH 60% GLASS FILLED NYLON
Magnesium is the lightest of common structural metals (Specific Gravity 1.74). It is 34 % lighter than Aluminum and 74% lighter than Steel. In addition, magnesium is one of the earth's most abundant elements, with virtually inexhaustible supply (2,7% of the Earth crust). One of its nicer advantages, compared to plastics, is that it is easily recyclable and readily reused without any loss in mechanical properties (at least that's what is claimed).
Here are a few of the mechanical properties of two magnesium alloys.
A specially formulated nylon filled with long glass fibres is used for crucial mechanical parts like the rear suspension unit. The expertise to injection mould this lightweight yet strong material, which is 60 per cent glass, was provided by UK-based Protomold. I have written about Protomold in a past post, exploring how they helped in the development of the iBike cycling computer body unit. Click here to read that post.
Protomold engineers reported that they encountered a unique situation working with the Gocycle. Said John Tumulty, managing director of Protomold :
“With the GoCycle parts we were really pushing the boundaries of what is possible with plastic, and therefore the materials specified were, in the main, exotic thermoplastics. A very dominant material in the range is 60 per cent long-fibre glass-filled nylon, which is pretty extreme in terms of the glass content, coupled with the fact that it’s long fibre. During the moulding process, those fibres have a tendency to align with flow direction. The way the fibres are aligned affects the mechanical properties of the end part. Our mould technicians here have hundreds and hundreds of years experience between them yet hadn’t worked on anything like this, so it was interesting work. We knew we had incredibly short lead times, which also added to the challenge. On a simple, run-of-the-mill plastic part we can turn that around in 24 hours, but with the GoCycle components we had identified that we were going to have engineering challenges ahead. With that in mind, we pulled out all the stops so that we had more time in the mould shop to experiment and play with the moulding parameters."
"As with most things, the more mechanical property-orientated a material becomes, often the less aesthetically pleasing it becomes,” says Tumelty. “Glass fibres can have a tendency to show up on the surface of a moulded part, which on a black plastic will give a silvering effect. In layman’s terms, you’re looking at the black plastic through a fibrous glass layer. Obviously that’s not very attractive. There’s also quite a lot of effort and experimentation that went into the parameters of moulding the part in order to not only attain the required mechanical properties, but also to get the cosmetics to an acceptable level.”
DESIGN AND SPECIFICATIONS
The development of the bike took some six years from design conception. PRO/ENGINEER Wildfire, a parametric, feature based CAD software was used in the design (similarly, it is now widely known that TREK uses Solidworks).
Interestingly, Richard gives hints that one of the reasons he left Mclaren was due to lack of Pro/E at the company (some companies have their own internal, proprietary CAD systems that could be cumbersome to work with).
Now here are the tech specs of the bike :
The GoCycle can be pedalled like a conventional bicycle until the rider hits a button that revs up a high-powered electric motor in the front hub. It can travel at full legal urban driving speed for about 12 miles before needing a re-charge. The transmission is a Shimano Nexus 3 speed hub. These 3 gears are operated by a twist grip on the handlebar.
But there was an interesting noise issue with the motor. Said a review from Velovision :
"The assist motor is engaged by pressing the red hutton to the left of the handlebars: the motor then kicks in after four turns of the pedals. I must admit I found this strange - it's those first four turns where you need assistance the most when accelerating off traffic lights, for example. I also noticed that the motor doesn't have a lot of torque at low speed - so if on a hill start you're still moving slowly, it will struggle to accelerate you. On the same hill, get up a bit of speed first and it will boost you up powerfully. It's also good to speed you up for longer stretches in traffic. The motor is quite noisy, but not so much as to be an embarrassment. It does have a loudish whine: other cyclists or pedestrians you overtake will definitely know you've engaged the motor and many looked round to see what it was."
The noisy motor issue is in fact called by Gocycle to be a deliberate design feature!
"We were looking for the fun, spunky, get-me-there vroom-vrooom-vrooom attitude for the city commute."
The need for some vroom-vrooom is hardly surprising considering Richard's roots in McLaren.
The company representatives also said about the battery :
"Considering the total vehicle - weight, range, performance, cost, safety - Gocycle is one of the lightest electric two wheelers available as well as being competitively priced. Considering this is based on NiMh battery chemistry, the inherent safety margin that NiMh offers over Lithium based batteries is a bonus. Lithium batteries will be available as an upgrade option in the future, same battery case same Gocycle frame, but at a higher price than NiMh. The increase in performance will be about 1-2 kgs of total weight savings of the entire vehicle with slightly more range."
PRODUCTION PROCESS
Thixomoulding is a net shape forming process that exploits a commonplace, but interesting property of non-Newtonian pseudoplastic fluids. Its called thixotropy. Pseudoplastic fluids exhibit a time-dependent, reversible change in viscosity; the longer the fluid undergoes shear, the lower its viscosity (by the way, a fluid is anything that flows upon shear). When not subjected to shear, it forms a gelled structure. When agitated mechanically, its internal structure temporarily breaks down causing a reduction in viscosity.
Toothpaste is thixotropic. It is much like a solid when left alone. But when you squeeze it, applying a sideways force through the tube, it flows much like a liquid. Thixotropy is why you never construct a building on sand. What happens when its visibly wet and there's a sudden earthquake? Whoops.
Thixomoulding uses this property in injection molding semi-solid magnesium slurry under high velocity into a mold. Magnesium feedstock (in chips or pellets) is added from a hopper into a multi-zone, temperature controlled barrel with a reciprocating screw. The screw is surrounded by heating bands and its rotational action mechanically shears the heated metal creating a semi-solid mixture of Mg alloy. This alloy is then injected into the mould. After metal injection is complete, the end of the screw freezes shut. The plug that forms keeps the semi-solid mixture from leaking out of the screw [Source : High Intensity Die Casting Processes, Vinarcik, E).
However, Thixomoulding application involves a set of structured design processes. As with any manufacturing procedure, you have to orient your design in a manner favorable for the manufacturing process (form, structure, material tolerances etc). Some of these design processes to be thought about for thixomoulding are outlined here.
150 production Gocycles have been produced and are currently being evaluated by what the company calls "Pioneer Customers". The availability of the next batch is in March 2009, and anyone interested in ordering can visit www.gocycle.biz to take advantage of special pricing. The retail has so far been placed at around 1000 dollars for a non-motorized version and an extra 500 dollars for the motor system.
WILL IT BE SUCCESSFUL?
Certainly Gocycle is a fresh departure from the norm in what many would consider a stagnant industry. It looks aesthetically sound and other design features quickly bring second looks. Velovision explored most of those features in their review of the bike here. The folding action is not too shabby and the hard case for the bike is impressive.
1) I must admit that it is vital that these first production units from Gocycle do not get a bad image due to technical/product failure. How strong is the frame as far as material thickineses are concerned? Will the long cantilevered seat post support the weight of a rider reliably? In writing "The 8 Second Bicycle", I talked about how Kirk die cast magnesium bikes quickly fell from grace due a poor show in terms of safety in the very initial stages of its launch.
2) There is going to be some stiff competition other folders from Strida, Brompton, Dahon, Friday etc. How is GoCycle going to differentiate itself?
3) Customers are bound to get intimidated or concerned because of potential fire and safety problems involved with magnesium. Few customers would know that today, magnesium alloys are used in such diverse industries as automotive, computers and sporting goods. I think it would do GoCycle some good to educate people on the materials used, the technology used, and how it is safe for human use.
4) How cost effective is the Thixomoulding process? I realize that Thixomat holds the exclusive worldwide patent rights to this process so will final cost passed on the customer absorb the licensing fees for this technology?
5) My last question is that while centralizing production facilities in the UK is good to customers there, would it lead to slow distribution in other geographical locations?
It would be great to have Richard Thorpe talk about some of these issues. So feel free to comment on my blog here.
UPDATE (Feb 26, 2009) : Richard Thorpe has replied to my questions one by one. Please see the comments section for his thoughts.
Anyone else? What comes to your mind when you first think of words like 'magnesium', 'glass fiber' etc?
In October last year, the Bicycle Design blog hosted a competition called "Commuter Bike For The Masses". The theme of the competition was centered around designing a 'transportation-oriented' bicycle to try and reel in (or attract) the vast "blue ocean" of people out there who don't ride at all, and have zero prior interest in cycling. Design and form factors were entirely up to the designers. The idea sounded fun, and Cannondale sponsored the competition. Winners would get a grand prize equaling a free Cannondale Bad Boy Bike, valued at 1000 US dollars.
The 7 jurors were :
James Thomas - Industrial Designer and the blogger at Bicycle Design
Out of 65 total entries, it was announced that 6 made it as finalists. They had some interesting, and creative concepts from a bike that would become a lock when folded, to bikes that had a car like feel to them, both from a design standpoint and other specific elements such as the idea of using 'keys' to get something unlocked.
Yesterday, the winner was announced and it was the "This Way" commuter bike concept from designer Torkel Dohmer. Congratulations!! Man, I fail to see how you can't enjoy that grand prize!
Here are my thoughts on the design, and you can think about them too :
1. ALL CAR DRIVERS? : It appears it was taken for granted in the competition that all non-cyclists drive cars. How about those who take the public transport system in cities (many are happy with public transport) ? What about the many others who're much satisfied with walking? How about those who don't want anything to do with cars at all? Will a design that looks and feels like a car answer all the questions?
2. JURY : Close to 60% of the jury I mentioned before consisted of people who ride bikes or are in the bicycle business. How can you avoid a selection bias or be able to get information from people who don't ride, like through a survey?
3. SOLAR PANELS? : In the design rendering, there are no solar panels depicted at all on the roof. Just a mere glass like structure. That doesn't say much, does it? Moreover, while solar power isn't necessarily bad, it could be expensive. In 2005, the price of solar panels averaged about $3-$4 USD per watt of installed power. The designer of the bike has to calculate how much power all his electrical equipment in the bike would need and justify the costs of buying, and installing solar panels to run the calculated watts and amperage. Then compare those costs with batteries. Whats a better option?
4. WEATHER PROTECTION : By weather, I take it that this bike can be ridden in the rain. The bike has a roof, so it is supposed to have that weather protection. But does rain only fall directly vertical?
The bike also has solar cells on the roof, which, according to the designer must power the bike's built in LED lights. How do you protect all that equipment when it rains? Attention must be also put on the fact that the sun isn't directly overhead all the time. Solar panels in the real world are able to tilt and position themselves correctly relative to the sun.
5. SNOW : Conventional bikes can be ridden on the snow using different tires and many commuters ride to work in the cold. Due to This Way's low rider position and small wheels, I highly doubt whether it'll be possible to achieve this.
6. DRIVE TRAIN : The bike has a "belt drive". Belt drives don't work with multiple gear sprockets. You could, however, pair them with an internal geared rear hub but you probably won't be able to enjoy some things. That may also cost more than simple sprockets.
7. SAFETY : Will a rider be really safe with a low center of gravity? What if consumers think aerodynamics is not as important as safely getting somewhere. Will he or she be visible to the traffic? When its time to brake and stop, how do you get out without tumbing either way due to a loss of balance? And finally, a few things about the windshield :
1) I'm not sure how the designer aims to make the windshield. If it is some plastic or polymer, then the issue of scratches on it comes up.
2) If its going to be made of glass, there's no telling when the rider can impact his head on it in case of an impact or accident. My next question would be : Should a seat belt be provided to the rider? What would be the industry standards that have to be followed for vehicles with windshields?
3) The viewing range of the windshield can be restrictive to observation. Notice how its not only narrow, but the windshield frame itself can block the rider's view ahead. This may or may not be an issue, but still something to consider.
8. RIDING POSITION & COMFORT : I like the concept of a recumbent riding position for a commuter's bike for the masses, but it seems to me as if in this winner's concept, the rider's arms will be outstretched at the handlebars. How comfortable will turning and maneuvering the bike be in corners and in climbing on hills? In conventional bicycles, a rider can stand and pedal to generate more power on hills. However, no such provisions are on the This Way bike.
Also note that from the rendering, the design of the handlebars makes it possible for them to strike the windshield frame on turning.
9. PARKING : Without a stand or a stable support point, how do you park a two wheeler such as this? And what facilities are there on the bike itself to use with existing public bike racks?
10. BIKE TRANSPORTATION : Will this bike fit into a bike bag or an aftermarket vehicle rack for transportation? I don't see that happening knowing what exists in the market today. in high density urban areas, cyclists are seen placing their bikes onto trains or buses. Given the big dimensions of the This Way bike, I hardly think that's possible.
11. MATERIALS OF CONSTRUCTION : The concept is to be made out of carbon fiber or flax fiber, and hydroformed aluminum. We all know that bicycles and velomobiles made out of carbon fiber are not cheap.
12. PRICE POINT AND LIFECYCLE COST : The judges think that to keep costs down, this concept could borrow ideas from toy and boat manufacturers and be made to sell under 500 dollars if volume took off. Pay attention. "IF VOLUME took off". Otherwise, they think selling point will be around a 1000 dollars. Now, none of the judges have talked about a certain element called 'Risk Assessment'. By using composite materials and having solar panels on your roof, is it guaranteed to attract consumers? This isn't simple to answer in a day or two. Its all too simple to sit somewhere and say, 'My idea is going to be great. Lots of people are going to buy it. My competitors will be dum as well. They won't figure out a cheaper, easier or more innovative way to do things.'
Keep in mind that the materials of construction, solar panel and electrical transducer equipment, wiring and the extra cargo attachement that goes with the bike can all bump up costs. To rely on manufacturing methods for toys and boats can also have its own set of agendas to follow, such as having to follow different sets of standards or testing. Considering all this, if it can still be sold for 1000 dollars, great. But is 1000 dollars what everyone wants to pay for a commuter bike?And over a period of its life, how costly will it get for the average Joe to maintain, replace and buy new parts due to damage, wear and tear? 13. COPY, NO COPY OR JUST DESIGN IMPROVEMENT? : In the summer of last year, I saw a concept very similar to This Way. It was a solar powered bicycle designed by Miroslav Milijevic based at Z & Co. Design in London. It was called Cycle Sol (Sol may be short for Solar). The only differences I see are that Cyclesol has an electric assist motor, the handlebars are positioned at the sides, the seats look a little less comfortable and wheels look more solid. Even though such a design was shown months earlier, even it seems like it didn't transform into reality till now. Yet, the design renderings have substantial detail in them, which is how I think a proposal should be submitted.
14. WILL IT TAKE OFF? : For all the publicity that surrounded this competition, what I'm really interested in is will the concept see the light of day? Congratulations to the winner, but there appears to be a need to have a reality check put on the design. I hope you can work and build upon the apparent practical disadvantages I and many others see in this concept.
At the end of the day, ask yourself the question : Is poor bicycle design really the culprit in keeping people away from cycling, as opposed to safety problems, poor infrastructure, poor riding facilities and poor advocacy programs by governments and other authorities? If it indeed is, by how much (like a %) ? What amount of role does it play in discouraging cycling? Because if it is indeed a tiny % compared to other factors, then maybe the best efforts to get people on bikes can be achieved through strategies trying to improve those other factors.
