Part failures are a common story in world of cycling - be it metal or composite parts. If you have ever experienced a metal part failure yourself that was a factor in any injury, have that part sent to someone knowledgeable in metallography.
Metals have existed for thousands of years and both their theory and their analysis have been perfected through science. Mainstream carbon composites sprang up during the 50's and 60's so understanding them is still bit of a niche field. But who hasn't bent or welded a metal part in their garage at some point in time?
Speaking of metal failures, agencies exist today that not only can analyze a specimen of a failed part blown thousands of times larger by microscopes but they can also perform chemical and impact tests on the part to determine if the composition of the metal was as per the specifications, and whether attributes related to heating - such as the thermal alteration during welding and cutting - had any part to play in the breakage.
A nice overview of these processes was provided recently by the ME Magazine. With this brief introduction, it may help you decide whether its something you want to pursue through an expert if the injury case is significant. This route may cost a good amount of money but both accuser and the accused can come to an agreement as to who was at fault in a technical and professional manner. One example of a case where metallurgic expert lent his insight to the victim of a bicycling accident was explored in one of my previous blog posts here.
There was a video made by a Dutch TV group about Specialized Bikes' design process. Observe how they're using their rapid prototyping printer to create preliminary designs for approval. Another company I can think of, right off the top of my head, that does the same is Giro eyewear. Of course, I'm sure there's more. Back in the old days, something like this would be done by a dedicated team of concept artists.
The printer is essentially the same as any paper employing printer, except these ones use molten plastic and build them in layers in a process called Fused Deposition Modeling. So the one at Specialized is a Dimension SST 1200 that builds a model in layers of 0.010 inches thick. Its pretty fascinating to see one in action. Like this :
Do you use 3D printers in your projects? I haven't, but I have often wondered about the kind of part geometries these things can't handle. I have seen parts made from 3D printers and those ones don't look too nice surface finish wise. But hey, it gives the message.
Before you go ahead, I want to take this time to wish you all a Merry Christmas. If the downward spiraling economy has taken a toll on your finances and your kids are wondering where this year's gifts are, tell them Father Santa had swine flu and is in bed rest. :)
The following video from Giro's headquarters explains how they design sunglasses. What you'll see is a bunch of guys brainstorming design patterns. Then some of them produce said designs on CAD, later rapid-prototyping them on 3D printers to test the initial look and wear of the frame.
The Futures Channel has an interesting 10 min segment on the making of sunglasses. Again, Giro is the eye wear brand featured and the presentation goes a little into the behind the scenes manufacturing and testing at Giro's optics partner, Zeiss. The latter creates the lenses for Giro. The video can be seen by clicking on the image below.
You'll see in the above video that sports eye wear start their life as little pellets of polycarbonate (Abbe # = 31), which are then combined with specialized dyes to tint them which are then melted to ensure uniformity of color. The pellets are applied into an injection molding machine at high temperature and pressure and what results is the familiar look of an eye-shield.
Eight different types of washing later, the lenses get reflective and anti-scratch coatings. Optical coatings in lenses are almost always made of magnesium fluoride (MgF2). Sabrina Malnati, the manager of R&D at Zeiss Vision Sun lens Department, reviews their resolution, prismatic, impact and abrasion test protocols and the international standards that govern them.
What interested me most in the video is how the tints are created for these lenses using soluble organic dyes and metal oxide pigments. Tints are associated with enhancing optical attributes of lenses such as clarity, contrast and sharp vision. Designing towards an optimum tint is a subtle process. The highest quality lenses are optically accurate and do not distort shapes and lines or give the wearer discomfort.
What upset me is that Futures Channel calls the video the "Science of Sunglasses" but little is said about the optical science behind such eye wear.
So here are a few good resources I have collected if you want to learn more about the exciting field of lens optics from a technical standpoint.
Testing of sunglasses are really important not only because these things protect your eyes against harmful sunlight but also against impacts that could tear a hole in your eye if needed. I couldn't help attaching this explanatory video from Oakley's lab because the speaker, Bryan Shelton, seems to really knows what he's talking about. Enjoy.
Ever since the start of this month, Lynskey Performance Bicycles based in Chattanooga, TN has been quietly uploading videos of their manufacturing processes to the internet. As you know, Lynskey is the founder of the brand "Litespeed" which goes back a long ways. If I'm not wrong, it is now owned by another TN based company, American Bicycle Group (ABG) which makes the featherweight Ghisallo frame (weighs about 1.7 pounds). Did you know that apparently, even NASA's Jet Propulsion Lab buys tubing from ABG? I didn't want to shift topics, but something like that really speaks for the quality of titanium tubing these companies deal with. Now in the past, I have showcased some history of the machining technology David Lynskey used in his Litespeed facility on this blog, so click here to read that article if you haven't. Today, Lynskey works with U.S. milled aerospace grade 6AL-4V and 3AL-2.5V titanium and each bike is handcrafted to customer's needs using some special technology.
After some interesting hunting, I learnt that two new Mazak machining centers (CNC milling machines) were installed at the Lynskey facility. One is a Quick Turn Nexus 200-II and the other is a Vertical Center Nexus 510C-II. These babies are "the Cadillacs of CNC machines". These options will give them design and manufacturing flexibility, productivity and time savings.
In the following sample video, we can see the 5-axis tool path in creating a fork dropout and a headtube badge. This is actually created in CAD/CAM which generates the NC machine code, which is then fed to the Mazak machine via Ethernet cable. The machine now knows "what to machine" and "how to machine" it. This is one episode in a series of videos called "How We Make A Lynskey". I encourage Lynskey to go ahead and keep showing normal customers what role these machines and tools play in the big scheme of things. There is great value in not only purchasing and riding a certain variety of bikes but also learning how they're made.
While I was away for a week, I saw that a bunch of you replied in comments to the "Who, What, Where" contest. Thank you so much for your thoughts. It gives me better insight into what some of my readers actually do in life. Now I will keep the contest and the comments section open for one more day. If you're a reader and you haven't checked it out, please do now. Comments close 12pm on Friday, July 17.
Let's get that persistently annoying housefly at your place a new hobby. Let him ride a bike! The smallest bicycle in the world has no practical application for humans. Researchers at Swiss-based GF AgieCharmilles played around with the capabilities of small wire electrical discharge machining (EDM) to produce a micro sized mountain bike. Check this out : The tiny cycle was machined out of 1-mm-thick Inox stainless steel (steel alloy with a minimum of 11% chromium by mass) using a 0.020-mm wire. The smallest internal radius measures a mere 0.013 mm it seems, with a tolerance of +/- 1 μm!!
Check out the width of the headtube - 30 microns. Thats about the average diameter of a human hair.
EDM is a thermal machining process that shapes electrically conductive, hard metals by using precisely controlled sparks that occur between an electrode and a workpiece, in the presence of a dielectric fluid (an insulator that becomes an electric conductor at a certain voltage).
Here, the electrode is the cutting tool and it does not make contact with the workpiece, instead maintained at a distance called sparking gap. Hence, there is no tool stress. Sparking occurs in the frequency of anywhere between 2000 to 500,000 sparks per second. As each spark occurs, a small amount of electrode and metal is vaporized. This causes the sparking gap to widen and the next spark occurs at the point with the closest gap. What is interesting is that the vaporized metal and electrode forms a cloud in the dielectric. When the spark is turned off, this vaporized cloud hangs suspended in the same and solidifies to form an EDM chip. This chip is then removed by flowing dielectric through the sparking gap.
According to Design News, one of the biggest obstacles to overcome in achieving these ultra-small features in the bicycle was in controlling the sparking gap. The Head of R&D Micro Machining Dr. Ivano Beltrami of the Swiss company said, "That means first being able to electronically measure a distance between electrode and work piece at the level of only a few (two to ten) micrometers and second being able to keep the gap width relatively constant." It's particularly difficult, he said, because of the particle contamination in the dielectric and the stochastic nature of the spark formation.
Asked if the wheels on the bike actually spin, Beltrami replied "No, it's challenging enough to actually have the wheels at all."
I agree with him. It'd take something of a miracle to make working bearings for those wheels. But you never know, considering the pace with which nanomanufacturing is coming up. For instance, check out how the National Center for Electron Microscopy (NCEM) custom-engineered seemingly frictionless bearings a few billionths of a meter in size.
Here's the EDM process I described to you above in action! Enjoy.
1. Mass Produced Metal Alloy Bikes : Episode 3 from Season 1 of Science Channel's How Its Made series explores the making of bicycles. The narrator was the show's first ever anchor, Mark Tewksbury. Now some of you might be bothered that this is not the "enthusiast" level bicycle and may even ridicule it for its lack of craftsmanship. The manufacturing steps are really interesting to look at regardless. Some of you may also be bothered by Mark's accent. It may help to know that he's a Canadian with an interesting athletic background and How Its Made is a Canadian documentary. For nerds like me, watching this show is better than having ice cream. Let's hope they run it on Discovery forever.
The part on bicycles starts from 0:43 seconds. Video courtesy --> bamboopasia.
2. Colnago & Milano Carbon Bikes : Part of Bike Radar's 'Industry Insider' series, they have a video revealing the full production process of a Colnago EPS frame. It shows how the filament wound carbon fiber tubes are cut and glued together with lugs. They are then placed in a jig to ensure proper alignment and cooked in an oven to cure the bonding agent to create the carbon frame, after cooling ofcourse.
While you're there, also check out the recently uploaded section on how Milani Bicycles in Italy create carbon fiber prototype frames. The video shows the laser cutting of carbon fiber sheets, making of small prototype parts, and the vacuum bagging and autoclave baking process for carbon fiber frames. There's a really hilarious section towards the last 3/4th of the video when an employee at the company comes from behind, blocks the camera and admonishes out in Italian yelling "Hey kids, what are you doing here? You can't film. Everyone out!!" Ha, that was classic. I really think it may have been a joke. Or else, Bike Radar may have forgotten something in the editing process. Surely that uomo can't drive out a bloke like that. Che cazzo...?
3. Cyfac Custom Carbon Frames : Chris from Texas shared with me this video from French custom bike manufacturer Cyfac. The video shows carbon tube assembly and "Carbon Stratification" which is basically their multi-layer reinforcing procedure. In this process, they combine custom molded carbon fiber tubes, epoxy, and three layers of carbon - Kevlar, serge carbon (twill) and taffetas carbon (crisp, smooth, plain woven). Now I have read that as a result of the differentiated fiber layers, stratified composites are particularly susceptible to bending at the side of the composite where the lower denier fibers are located, or in other words, its not as stiff as a homogeneous composite. I wonder whether this structure affects the Cyfac frame in certain situations. Feel free to comment.
Readers will remember that I blogged last year about the brilliant underground bike parking system made by the Japanese at Nishi-Kasai Station in Edogawa, Tokyo. I just happened to discover a cool video from Japanese news broadcaster Newsline which details how one of these these automated parking systems, called Eco Cycle, was designed & constructed and the machines which were employed in the process. This really looks to have been a neat little civil engineering project for the developers - Giken Seisakusho Group.
A picture of Giken's 'Silent Piling Machine' which takes prefabricated structural piles and presses them into the ground at high pressure without vibration and excessive noise. Courtesy Giken.
I've not ridden a velomobile myself as yet. But if my observation about their design is not too ignorant, I don't see how a fully enclosed recumbent will be comfortable riding in hotter temperatures. For one thing, the recumbent now acts like a greenhouse, trapping the sun's heat in, while the other source of heat is the rider himself. Since the rider is actually doing work to pedal, heat is given out. How much heat? Its depends. To put things into perspective, even while at rest, an adult radiates heat at the rate of 80-90 watts (BMR = 1.2 watts/kg for a 70kg individual) as a result of basal metabolism. But now because of the recumbent being a greenhouse, the ambient temperature inside the vehicle rises. At higher temperatures, the body cannot radiate heat effectively. But the human body is a remarkable temperature regulation machine in that we have temperature sensors in our brain that activate the evaporative cooling mechanism when the ambient temperature is in excess of 30 deg F. But the catch here is that in order to get blood to the skin to aid in this process, there is some amount of cardiovascular strain on the rider's body. Irony also has it that as you sweat and lose more salts from the body, you face additional strain on your cardio system.
Bottomline : someone sitting in a velomobile to travel extensive distances must have a cooling system already built into the vehicle, or he or she must be able to tolerate such temperatures and cardio strain within an enclosed space for long periods of time. I mean, what are the odds that you won't die of a heat stroke riding something like this? Let's not forget that one of the ultimate joys of riding a conventional bicycle is the soothing feeling of a cool breeze skimming your body.
Are velomobiles designed to have vents in them as an escape mechanism for heat? Or must they come with a neat little air conditioning system of their own? I think if designers were to take live heat loads into design consideration (like the design of HVAC in a building), the velomobile will have great potential as a comfortable vehicle for longer distances.
What do you think? Have you ridden a velomobile? Do you find that their ventilation systems are adequate for long travel in hot temperatures? Let's discuss.
I gave my groin to Spandex A fruit of Dupont's 'projects'. I need not dread, wearing a rubber tread, for now I have my Spandex!
I gave my groin to Spandex A fruit of Dupont's 'projects'. Miles in peace, minus the woolly crease. O' that's a ride in Spandex!
I gave my groin to Spandex, A fruit of Dupont's 'projects'. Neither oil or sweat, nor detergent has met the destruction of my Spandex.
I gave my groin to Spandex A fruit of Dupont's 'projects'. A godsend elastane. Mind you, its a polyurethane! Well... I just call it Spandex.
Did You Know ?
So valuable was DuPont's spandex technology (1962) that it was the subject of an extortion attempt in 1989. Five DuPont employees, all from DuPont's Lycra spandex plant in Mercedes, Argentina, tried to play a fast-and-loose game. They stole proprietary production technology documents and attempted to extract $10 million from DuPont for their safe return. After a globe-trotting chase that included stops in Wilmington, Del.; Milan, Italy; and Geneva, Switzerland, the Federal Bureau of Investigation and Swiss police finally staged a sting to exchange a bogus check for the documents. The operation went awry, but the Swiss police ended up nabbing the extortionists on the rebound in a Geneva parking lot. [Source]
Besides Lycra®, DuPont is also credited with discovering Kevlar® fiber in 1965 and Teflon® earlier in 1938. These materials are increasingly used in the bicycles today to make friction decreasing cables for flexible and supposedly crisper shifting, and as a puncture preventive component in bicycle tires. The Specialized S-Works helmet also licenses Kevlar to employ it as a structural base reinforcement.
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.
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?
How does powder coating work, and how is it better than spray and liquid painting? For starters, there's something involved called the principle of electrostatics (the force on a charged point exerted by a second charge is proportional to the product of charges, and inversely proportional to the square of the distance between the charges...blah blah blah). Its clean, its dry, and most of all, you get a tougher surface finish. Anyway, watch this video - courtesy of Eastwood Co.
Brooker Enterprises specializes in Powder Coating. In this video, they show you how they powder coat a customer's frame to her color of choice. Video courtesy of crankmychain.
Metals have existed for thousands of years and both their theory and their analysis have been perfected through science. Mainstream carbon composites sprang up during the 50's and 60's so understanding them is still bit of a niche field. But who hasn't bent or welded a metal part in their garage at some point in time?
instead maintained at a distance called sparking gap. Hence, there is no tool stress. Sparking occurs in the frequency of anywhere between 2000 to 500,000 sparks per second. As each spark occurs, a small amount of electrode and metal is vaporized. This causes the sparking gap to widen and the next spark occurs at the point with the closest gap. What is interesting is that the vaporized metal and electrode forms a cloud in the dielectric. When the spark is turned off, this vaporized cloud hangs suspended in the same and solidifies to form an EDM chip. This chip is then removed by flowing dielectric through the sparking gap. 
A picture of Giken's 'Silent Piling Machine' which takes prefabricated structural piles and presses them into the ground at high pressure without vibration and excessive noise. Courtesy 
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