Dr. Chester Kyle : Pioneer in Human Powered Vehicle Aerodynamics

Chester Kyle, PhD is a pioneer in cycling science and the aerodynamics of human powered locomotion. Now retired, he served as an adjunct professor of mechanical engineering at the U of California at Long Beach for several years. He also served a stint at Nike designing aerodynamic clothing. 

When you read the breadth and scope of his work, you really will be surprised how much of aerodynamic design and technology that has infiltrated cycling, whether real or gimmick, had been already explored by him and his students. From drivetrain efficiency to the aerodynamic drag of a shaved vs unshaved cadaver, there was practically little he didn't explore and write on.

Several ideas introduced by him and his peers at the US Olympic committee and human powered vehicle circles went onto win international cycling championships and setting speed records. At the height of his career, the UCI was hot on the chase of these "ideas", banning several of the improvements broguht to the UCI sanctioned cycling races. As Dr. Kyle likes to joke, 'the minute they saw them [plop], they became illegal'.

Dr. Kyle's investigations into technical aspects of cycling through simple experiments driven by a sense of economics and curiosity for the science should serve as an example for any investigator today. The most important aspect of these investigations was that he helped produce a body of empirical data that let other researchers and designers go about their business.

On 13th May 2010, he was invited to a seminar for the students of MAE297.  The following is the video from that lecture. An amazing little talk, and made no worse by Dr. Kyle's upbeat attitude and quirky sense of humor. 

Credits :
Film by the UC Davis Engineering distance learning program, 2010.

Self Inflating Bicycle Tire Shows Up Again

William Powers, a team member of a new start-up group called PumpTire LLC, informed me a few days ago of their self inflating tire idea. James of Bicycle Design had posted on his blog that he received the same email as well so I figure that this made the rounds to many bloggers in a mass email.

The idea appears to be the brainchild of Benjamin Krempel. The internet describes him as a CEO of Aqueduct Medical, a company that develops "safe, effective, user-friendly products that improve patient recovery from facial and cosmetic surgical procedures."

In the video below, he describes the idea (although somewhat vaguely) :



So its basically a pump that operates every time its squished by rolling motion. "The tire is a 26” x 1.5” tire with a set pressure valve", says the product website. Reportedly, the tire inflates from zero guage pressure.  "The pumping mechanism will pump from a flat up to 65psi."

In a blog entry back in 2008, I listed some "new" cycling ideas that would be serve as cool thought experiments, without exploring any technical or economic aspects. An "on the go tire inflation/deflation system" was first on my list and it had an almost science fiction aspect to it - the idea that the tire would have a feedback system to it to monitor pressure while riding and adjust itself after sampling pressure.

One application where this would be attractive is in public bicycles used for bike share programs where a self inflating mechanism could possibly add to some convenience. It avoids the necessity of adding an extra infrastructure for pumping air by the sidewalk or the need for individuals to carry pumps. For utility cyclists, terms like "rolling resistance" or "wheel inertia" are usually unimportant. Most just want to get from point A to B.

Having said that, a safety feature in the system is a must. The tire shouldn't injest water along with air. It also shouldn't over-pressurize and lead to tire bursts. Things like that. In the end, an interesting thought experiment ends up consuming time being developed, tested, re-tested, re-designed, at the same time needing to raise funds for the development and meeting the demands of consumer standards and regulations. By the end of it all, the inventor will want to go for a serious ride to breathe some air.

The idea of a self-inflating tire doesn't appear to have sprung up now. A few others tried to do something on similar lines, one of them if I remember correctly was an entry for the Specialized : Innovate-or-die" contest that happened a few years ago.

Here's Sean Conley back in 2007 :



And here's Kevin Manning, also in 2007 :



Both appear to charge air into the tire through pedaling. A bunch of patents on "self-inflating" tires for cars and bicycles date back to 1800's. Those can be found by a Google Patent search. That's what happens when you give people too much leisure time.

Whether Krempel actually first came up with the idea or not is not the issue. The big picture as I see is perhaps that of the slow march of the bicycle towards fulfilling an intelligent, self correcting system. Automobiles, ships and airplanes are already there but the "control architectures" in these complex systems are the by-product of externally driven factors - federal laws or economic incentives. Will the bicycle really benefit from that kind of intelligence? Sounds like a philosophical question.

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Bicycle Chain Stretch Test & Results

Do bicycle chains get stretch marks? Will smearing cocoa butter on them be a step in preventive maintenance for future? I don't know, but hold that thought for a moment.

I, like many, am a fan of chains. For bikes, they present a technology that is  ubiquitous, economical, and proven to work almost seamlessly with external shifting systems. Belts are slowly staking their claim in the single speed road and mountain bike arena, however I have to be honest - show me a more simpler, self cleaning power transmission mechanism that doesn't load up shafts and bearings as much as a belt does, and I'll be sold on other ideas. 

".. the less stretch, the more responsive the bike becomes.."

But in cycling, as we all know, equilibrium is rare. Everything has to get scrutinized more thoroughly than a coroner would do a murder victim, from the pimple on our skin that's disturbing laminar air flow to the secret ingredients used to make those mundane Presta valves and you know, that's what keeps our world a bit interesting (or not).

Now if you just may recall, Wipperman was getting fancy in the recent past by testing a host of chains in order to rate them according to their wear rates. You can read that blog post here which described the test protocol, the results they came out with and so on.

Recently, I was told that the company commissioned a different test on a similar selection of chains to test for elongation under load. Tom Petrie of Cantitoe Road - a chain test data center - passed along some literature that said the following :

"Wippermann recently tested a number of popular 10-speed chains for stretch under load. For a reference point, each chain’s length was measured under a nominal load of 10 kg. Then each chain was measured under 75kg and 150 kgloads, and the results recorded. Not surprisingly, chains with cut-out plates and hollow pins stretched more than those with solid plates and pins. And, the chains that stretched least were the Wippermann’s Connex 10 series with solid plates and pins!

How much a chain stretches under load affects how quickly the load is transferred to the driven cog. The less stretch, the more responsive the bike becomes. And, less stretch means less energy is lost to stretching the chain! Especially in sprint, time trial, or hill climb events, reducing these losses is critical. 

Wippermann tested 31-link sections of chain. This is the average number of links under load between chain ring and cog. While the actual amount of stretch is small (from 1.10 to 2.15 mm) the differences are substantial. Among the various chains tested, the “stretchiest” stretched almost 100% more than Wippermann Connex!"

After testing, the data was cobbled up into a table to make sense of the results. They follow :

Summary of chain stretch test data

Elongation vs load plot

The document went on to make light of these  :

"In addition to raw material and proprietary heat-treating processes, the shape of Wippermann Connex outer plate is largely responsible for its resistance to stretch. Note that chains featuring elaborate side-plate cut-outs and hollow pins are the “stretchiest” while chains with solid plates and solid pins stretch less. But even solid-plate solid-pin chainswith sculpted “figure 8” outer plates stretch more than Wippermann Connex. The extra-strong rectangular outer plates on Connex chains contribute significantly to their resistance to stretch."

This stretching they're talking about should be nowhere big enough to cause a yielding in the chain material. So the material attains its original shape after unloading like a spring, and the real question then becomes - how will a 100 thou inch change in chain length in the worst case scenario affects overall power transmission efficiency? Is it any more significant than the normal vibrations introduced into the chain due to tensile load changes and sprocket tooth effect? Does the stretching get better or worsen in weaker chains when the chain is misaligned/cross chained? Finally in the big scheme of things, how will cyclic stretching/unstretching react with notorious elements like salt water? Could it possibly accelerate the failure of cut-out chains in those circumstances?

What do you think? While you sip your coffee, you may also be interested in glancing at a "shifting performance" study done on chains through Wippermann, the hardly surprising conclusion of which was that there is no observable correlation between a worn chain and shifting performance compared to a new one. You just may not want to break your bank over a chain.

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Best Tech Innovations of 2010?

The Cycling News Reader Poll has pedal based powermeters topping the list of best tech innovations of 2010, among 9 other items. Pedal based power meters, like the one introduced by Metrigear, will tell you how much workload each leg applies into cycling motion. Positive tangential, negative tangential and net tangential pedal forces are the jargon in the list of features it offers the user. Its a solid physics based tool and I reckon that most of you in the general public who rides and who have a natural perception for pedaling efforts anyway wouldn't require a gizmo to tell you what you probably already knew - that the dominant leg works 5-10% harder than the other.

Some of the other items in the list were :

Pedal-based power meters, 4521 votes (26.9%)
GPS-enabled computers, 4095 (24.4%)
Disc brakes on 'cross bikes, 2065 (12.3%)
Wide-profile road wheels, 1386 (8.3%)
Belt-drive drivetrains, 1122 (6.7%)
PressFit 30 bottom brackets, 970 (5.8%)
BBright multi-fit bottom bracket standard, 960 (5.7%)
Carbon fiber mountain bike wheels, 955 (5.7%)
E-bikes, 362 (2.2%)
142x12mm rear thru-axles, 351 (2.1%)

What innovation made most sense to you ?

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Matt Appleman On Carbon Fiber

Appleman Bicycles in Orange County, CA is the brainchild of Matt Appleman. After an injury called an end to his 10 year long bike racing career, he decided to pour the knowledge gained through his college Composites Engineering degree and work experience into building carbon fiber bikes.  Today, he builds custom carbon fiber bikes to suit the stiffness needs of a rider. The base price for a frame, fork, and headset is $3,500 and this includes a standard "three panel" paint job.

Besides bicycles, Matt has worked in the aerospace and wind energy industries. "From 150 ft, 13,000 lb wind turbine blades, to 2 lb bike frames... I've used composites to build them all!" he would tell you.

Matt is a follower of my blog and recently contacted me to express his extreme satisfaction (or dissatisfaction) with my website. After having learned his credentials, I chanced upon the opportunity to shoot him a couple of simple questions on CF without getting into an erudite discussion. His reply is as below. If you have further questions after reading it, feel free to contact Mike through his website or start a discussion here.


Me : Matt, you must be quite confident in carbon fiber's material properties for bicycle applications. I too believe in its benefits when properly applied. But when it shows its limitations, the consequences aren't so good. For the rest of us, tell us what makes a carbon fiber frame weak?

MA : Well it depends on a bunch of factors.

1) Material Properties : The inherent weakness of carbon fiber is that it is brittle.  Carbon fiber composites have low elongation (typically 1-1.5%).  The brittleness of carbon fiber can be seen from sudden impact forces like riding into a curb or large pot hole.  These impact forces can bend the frame/fork to the point of catastrophic failure.  The frame needs to be sufficiently strong to absorb impacts and transmit the force throughout the frame.

2) Design (or lack thereof) : The “layup schedule” or the number of layers and direction of carbon fiber is the most important aspect to building a strong bicycle.  For structure, bicycles use unidirectional carbon fiber meaning that all of the fibers run in the same direction (an isotropic material).  Woven fabrics are typically cosmetic.

Unidirectional carbon fiber is  30 times stronger in the fiber direction than perpendicular to the fibers. The angle of the fiber directly affects the strength of a frame!

There are many forces applied to a bicycle while riding it and each tube resists a unique set of forces. Each tube requires a unique diameter, number of layers, and fiber directions.  The true beauty of composites is that you can pick the direction of the strength.  To save weight, material only needs to be added in a select number of directions.  A carbon fiber frame with tubes designed with equal strength in all directions (anisotropic) would weigh at least twice as much and be overbuilt!  Unfortunately, frames often fail because of forces not considered when designing the layup schedule.  There is always a balance of weight and strength.

3) Manufacturing Methods : Then there are manufacturing methods. There are a 101 ways to manufacture a carbon fiber frame, but no matter how the frame is made, air voids can be present.  Air is the true enemy of composites.  Air can be trapped between layers of carbon fiber during the layup process.  If the air is not removed prior to the resin curing, a void will form.  For reference, a void content of <3% is considered acceptable in most composite industries.  The void is a stress riser that enables cracks and delaminations to propagate.  Whether failure occurs depends on the size and location void. 

Me : How do your bikes take care of this weakness issue?

MA : Appleman Bicycles uses high strength carbon fibers and toughened epoxy resin.  The carbon fiber is pre-impregnated with the resin to provide consistent  resin content and low weight.

By using a multitude of angles, the layup holds tubes together while transmitting loads and forces throughout the frame.  The loads are distributed along the length of the tube as well as throughout the cross-section producing an extremely lightweight and robust structure.

During my time working in the wind energy and aerospace composite industries, I’ve witnessed and developed hundreds of cure schedules.  Using my background, I designed new cure schedules specific for my process of building bicycles.  By using heat and pressure, air is extracted from the laminate prior to the resin curing.  After the air is removed, consolidation of the layers of carbon fiber is realized until the resin is cured.


Me : Thank you for your time!


SEE MUCH MORE RELATED READING ON THIS BLOG :

Effect of BVID On Carbon Fiber Bike Frames 
Broken Steerer Tube : Composites Are Not Perfect
Aspect Ratios & The Spirit of Cycling as a Sport

Cannondale Six 13's Bi-Axial Braid Solution

How TIME Makes Carbon Fiber Reinforced Bike Parts

Nanotechnology Application In Bicycles : How Good?

Why Some Carbon Fiber Is So Cheap?

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Metallurgical Failure Analysis

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. 

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Braking Induced Fork Failure

Here's another image of one of those braking induced fork failures that crop up from time to time. This was sent to me by a reader. The entire story of how the accident occured is mentioned on this blog.

Because of the lack of telescopic front suspensions like those nice mountain bikes have, rigid forks take the full brunt of a combination of two forces. One is the braking force that acts longitudinally backward to direction of motion but this has a component along the axis of the fork as well. The other is the force due to braking load transfer towards the front of the bike. This force acts inline with the fork axis. In essence, the two forces add together. I'm fairly certain that the quantity of this directed force along the fork is strongly dependent on the wheelbase of the bike and the rake angle of the fork. Lower wheelbases equate to more load transfer. Higher rake angles must also promote higher fork forces.

Undersized, thin walled tubes, such as forks, do not act kindly to hard braking forces. An example of this kind of buckling along with its physics was provided sometime back on my blog.

Thanks for reading. Have an enjoyable weekend and exercise safely.

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String Transmission

It looks like one of those linear drive systems have shown their face again. It was in 1897 that a patent, granted to a teen Swedish inventor Birgin Ljungström, showed the world a linear drive bicycle where the pedals moves in linear, reciprocating fashion. The project was sponsored by dynamite inventor Alfred Nobel. Ofcourse, numerous other linear drive systems for bicycles have been invented since then.

Recently shown on the Internet by a Hungarian bicycle design team was a linear drive bicycle. The system we're looking does involve circular pedal motion but the symmetric cam mechanism ensures that a string or rope constantly winds and unwinds on both sides of the bike, transmitting torque through the freewheel of the rear hub. Some videos are attached below to show the design and operation of the drive.

Discuss the possibilities and negative aspects offered by a symmetric drive system such as number of extra moving parts, ease or difficulty of adjustment, gear ratio variability, safety etc.

Alex Moulton Explains His Design Studies

Dr. Alex Moulton is a source of inspiration for me as a young engineer. I encourage you to watch these videos to see how a great mind thinks. The message couldn't be clearer. Good engineering is a hands-on job. If his biography weren't so expensive, I'd voraciously consume the book in one sitting overnight.

RELATED READING :

Mark Sanders Explains His Strida Concept
Design Case Study : Innovation Of The Brompton Folding Bicycle

F-One & Thirty-Six Seconds

Are you surprised that Armstrong wears 15,000 dollars on his head these days? Why? History has it that an entire empire is built around the guy to babysit him with products with which that he be marginally faster or psychologically faster. Its an incredible win-win situation for the producer and the user. Is there a better walking salesman that the most famous athlete? The following excerpt from the book Lance Armstrong's War, written by two time National Magazine Award finalist Daniel Coyle, sheds ample light on the cozy love affair and extent to which a company will go to satisfy the His Highness of cycling. One can perhaps derive a sense of why the Omerta is a sustainable concept in the industry. 

The riders’ bodies weren’t the only items being eyeballed in Murcia. There was also the crucial matter of the riders’ faithful steeds, their alter egos: the bikes. The following morning, as the riders prepared for the stage 2 time trial, bikes were everywhere: millions of dollars of tropical candy-colored frames stacked in casual piles next to buses, antlering team cars, whirring atop stationary trainers. The cycling press strolled among them, lofting the ritual questions: “How’s the new bike? How’s it feel? How’s it ride?"

This year’s plot was particularly thick, focusing mostly on the secret black bike that was now in some undisclosed location within the Postal compound, and whose attributes Armstrong was now discussing with journalists in front of the bus—or, rather, not discussing.
 
“You’ll see,” he told the breathless crew, which was clamoring for detail. “You’ll see.”

“Secret” was not quite the right word. A multimillion-dollar industry had been built around Armstrong’s equipment selection, an industry that feeds on the tideline between telling enough to sustain interest and not telling enough to give away competitive advantages. Over the past five years, Trek and Armstrong had become quite deft at this process, to the point where this particular bike, the construction of which had begun back in August, was the best publicized secret bike in history. The bike had been created by a task force of companies that called themselves F-One, and that consisted of whiz-bang experts from Trek, Giro, Hed Cycling, and Nike, among others. Numbers were being thrown around—it was one minute faster over fifty kilometers. Two minutes! After his first race in Portugal, two weeks before Murcia, Armstrong pronounced it “the fastest bike I’ve ever ridden.”

Exactly why it was so fast—well, that was the secret. The cycling media was abuzz with speculation—it was a new hand position, it was a new front fork—and each time somebody guessed, Armstrong would smile knowingly. “It’s something pretty radical, pretty deep,” he said. “Let’s just say that the bike’s fast and leave it at that.”

While Armstrong was being interviewed, two men were picking their way discreetly through a crowd, moving toward a stack of bikes. One had long gray hair; the other was younger, with a shaved head. They wore sunglasses and baseball caps and dark, rumpled T-shirts chosen because they lacked any betraying logos. The long-haired one toted a backpack and a dated, clunky 35-mm Olympus camera that any self-respecting bike geek would refuse to carry.

But they were more than bike geeks; they were high gods of bike geekdom, handpicked members of Armstrong’s F-One project. Their names were Steve Hed and Scott Daubert. Hed, a forty-eight-year-old Minnesotan, was founder and owner of his eponymous wheel-manufacturing company and was known as one of the foremost aerodynamics gurus in America. Daubert, a thirty-five-year-old Coloradan, was Trek’s liaison to the Postal team. They had come to Murcia for a variety of reasons, one of which was to spy on the other teams and report back to Armstrong. And like any respectable spies, they were worried.
 
Specifically, they were worried that some of the other teams might have caught on to F-One’s big secret—or worse, have come up with some new fast design of their own. This was the season’s prime information gathering time, after all. With four months to go before the Tour, teams still had plenty of time to make adjustments. Spies were everywhere. Two weeks ago, in Portugal, the F-One boys had a scare when they noticed some German guys with a camera skulking around the Postal bus, and they quickly covered up the secret bike with a black tarp. The Germans had turned out to be bored magazine photographers, but still, you never knew.

The F-One boys moved from team bus to team bus, mixing innocuously with the crowd, sauntering touristically up to the various bikes along with the rest of the curious masses. Hed carried a tiny tape measure in his fist; occasionally he would reach toward a bike, capture a measure, and let the tape snake noiselessly back into his palm. But mostly the two of them just looked, eyes blank as camera lenses as they roved over forks, seat posts, and cables. So precisely attuned were their minds that bikes registered not as shapes but as time—specifically as time savings per kilometer. “This bike looks like two seconds,” Daubert said. “That bike looks like one, maybe one and a half.”

The place Hed and Daubert gazed at most, however, was a small area called the bottom bracket, where the pedal cranks insert into the frame. The bottom-bracket width was an indicator of what was called the Q Factor—the distance between the pedals—and this distance held the key to Armstrong’s and the F-One project’s big secret.
 
Here was the secret: Armstrong’s new bike was narrower. Its bottom bracket was eighteen millimeters narrower than a standard bike’s. It wasn’t much—about the width of a pinky finger—but the change pulled the pedals closer together, creating a slimmer profile to cut through the wind. It was dead simple, and that was part of what made it such a pleasure for Armstrong to see the finest minds of the cycling world puzzling over it, focusing wrongly on the bars and the fork and all the extras when the truth hovered right in front of their noses—it was narrower! The narrow bike combined with the smaller changes (new helmet, new bars) had been measured as thirty-six seconds faster over fifty kilometers than Armstrong’s previous setup.

The competitive advantage of this advance was complicated slightly by the fact that the F-One boys most assuredly weren’t the only ones with the idea. Bikes with narrow Q Factors had been ridden on and off in track and road cycling for years. In fact, as the F-One boys would tell me a few weeks after Murcia, a handful of riders in last year’s Tour rode them, including Ullrich himself.
 
The reason that the F-One boys played those facts down undoubtedly had something to do with corporate spin, and the fact that it wouldn’t do to be seen as cribbing from a competitor’s approach. But there was something else in play here as well. The F-One project, as with so many of Armstrong’s endeavors, had confidence in its own supremacy. CS&E’s Bart Knaggs, who played a key role in putting the F-One project together, called this Armstrong’s “we can conquer the world” feeling.

“He sees all the facts, figures them in, but he doesn’t get hung up on them like you or I would, because he’s got faith in his decision-making process. That’s the engine that drives this thing. He knows—we all know—it’s going to be better because it’s going to be better.”

The F-One project had been born in a conference room in Armstrong’s agent’s office in Austin, Texas, on August 26, 2003. It was not an auspicious birth; in fact it was rather tense. In attendance were the brass from Trek: Ed Burke, Dick Moran, Doug Cusack, and Scott Daubert, along with Armstrong’s agents, his mechanic, Mike Anderson, and Johan Bruyneel.

“On the ride from the airport, we knew we were in for it,” Daubert said.
 
Bruyneel kicked off the meeting by pointing a long finger at Burke and telling him that the time-trial bike was too slow—it was old technology. It hadn’t been redesigned since when, 2000? Then there were the other problems: Armstrong hadn’t liked the last road bike, the Madone. And then the mixup with the fork, which had been caused, it turned out, by a human assembly error at the factory. Bruyneel laid it all out while Armstrong sat simmering.

Burke apologized. It was their fault, they would fix it, all of it. First and foremost, however, they would build Armstrong the fastest time-trial bike on the planet. Various ideas were thrown around, all of them limited by the fact that the size and shape of time-trial bikes are tyrannically constrained by the Union Cycliste Internationale. The narrow Q factor was settled on as a likely path, particularly given Ullrich’s success. The next step was obtaining a copy of Ullrich’s bike. Unfortunately, that bike was made by Andy Walser, the famed Swiss designer who produced a handful of frames each year for pros and recreational athletes. Figuring Walser would naturally balk at selling a frame to Trek, the company dispatched one of their European salespeople to Walser’s shop, posing as a wealthy triathlete—a perfectly legal subterfuge. The ruse worked. By the time Walser discovered the triathlete’s true identity, the bike was en route to Trek’s headquarters in Waterloo, Wisconsin, being prepared for dissection and testing.
 
Meanwhile, the industrial design process revved up, each detail flowing through the window of Armstrong’s BlackBerry. Mannequins were built, Nike’s skinsuit people were summoned, body doubles were hired, a new wind tunnel was found. The vivid spectacle of intercorporate effort helped persuade Armstrong to participate in “The Lance Chronicles,” an eight-episode OLN series whose first few episodes were devoted to the narrow bike’s development, and which was, in Knaggs’s words, “a win-win-win-win proposition.
 
A thousand images of Trek and Nike and Giro at work making Lance go faster—what’s not to love?” Viewers got a taste of the hours spent analyzing such seemingly tiny issues as that of the race number, which had an unkindly tendency to balloon out like a parachute and add thirty-six grams of drag, or about 1 percent of the total. Could they make a sleeve for it? Could they integrate it into the jersey? Tape down the leading edge? “We had long conversations over who would be the number pinner-onner,” Giro’s Toshi Corbett recalls. “It was like being at NASA or something.”
 
The beautiful part was, the exact same process was happening everywhere else in Armstrong’s world, a flurry of Cape Canaveral–like activity designed to fix what were regarded as the series of problems that had caused 2003’s near miss. Since Armstrong had been dehydrated, the Postal team started adding salt to its water bottles. Since heat had caused the dehydration, Carmichael started researching methods of staying cool, including heat-dissipating vests and tiny refrigerator-like devices that worked by cooling the hand. Corbett briefly looked into a helmet with a battery-powered refrigeration system built in, strong enough to give the wearer an ice-cream headache.
 
There was more. For the uphill Alpe d’Huez time trial, chief mechanic Julien DeVriese suggested using silk tires, which weighed a fraction of what conventional tires weighed. Hed and Daubert came up with the idea of profiling the Besançon time-trial course, mapping it with GPS, a digital level, and a wind indicator; examining historical weather patterns; and locating hedges and walls that might provide shelter. Anderson found an aluminum frame that allowed mechanics to replicate Armstrong’s preferred position on any bike with 3-D precision.
 
Here was the interesting thing: most of these ideas failed utterly. The salt solution tasted awful. The UCI was not likely to allow the ice cream–headache helmet. The silk tires were deemed too prone to puncturing. The course mapping turned out to be too complex to be useful, and the Belgian mechanics summarily refused to use the Dutch-built bike frame on point of national pride. (“They won’t budge,” Daubert said. “Not even Lance could convince them, I think.”)

Here was the other interesting thing: none of the failures mattered. The point was the process itself, in the way Armstrong transmitted his gaze through other people who hawkeyed the world to find the new Shit That Will Kill Them. The failures were banished, the rare successes embraced.

“We cannot have a feeling like we are standing still,” Bruyneel said. “For every ten ideas, perhaps one or two will be used. What it’s about is knowing that we have all the options on our side.”
 
“At some level, the science of it disappears,” Daubert said. “The important thing is that we get Lance something new and cool that he loves, and that’s what makes him faster.” 

To be sure, he was getting faster. The new wheels were light. The new skinsuit was fast. Best of all, the narrow bike itself was looking quite promising, which was underlined in January, when Armstrong road-tested it for the first time.
 
“What we want is for him to go ‘wow,’” Daubert said. “We try to catch him at a good time, or we’ll give it to an impressionable person, so they can say ‘wow’ and talk about it with him, warm him up.
 
“It’s a game,” he continued. “We have to be careful not to show him everything, or he’d be like a kid at Christmastime, and we’d be left with nothing. So we unveil things slowly, and we always keep an ace in the hole, something really cool we’ll give him right before the Tour. It’s kind of strange, but it seems to work.”
 
Armstrong didn’t like the narrow bike—he loved it. He tested it in Austin in December and again at the team’s California training camp in January, most memorably on a training ride where he started out on his regular road bike and switched partway through, letting the team go ahead. Armstrong powered up to them on the narrow bike and blazed past, a big smile on his face.
 
“How much did this cost?” he yelled as he rode. Hed and Daubert quickly ran the numbers: $250,000 so far, which made him even happier. Thirty-six seconds! It was beautiful!

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Composites Case Study : IsoTruss Frame For Tubing

This article appeared earlier in the year on Composites World. I do like to collect such articles as they go into interesting depth. Should you need more reading material, I have covered a few design specifics of the IsoTruss here and here.

I still feel that the cost and application of IsoTruss to bicycles is simply overkill. Analyzing how this structure will behave is a nightmare from the designer's point of view. Making it is time consuming and proprietary black magic. Imagine taking a space frame and triangulating it to absurd proportions. That is what you get, a structure as complex as the Infinite Isosceles Triangle. Engineers have made this mistake before. You should look up the absurd complexity of the 1960 Maserati Type 60/61 race car, famously known as the "Birdcage" (see right). The Italian designer Rodolfo Maserati probably thought that such redundancy would really give him the ultimate structure. The fact is that failures were common and their repair an absolute nightmare. For a one off car, economics probably wasn't an issue.

So I find the IsoTruss much suitable for large structural work and race car applications because those guys have plenty of money to spill.

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New Twist In Cycling: A Truss Bikers Can Trust

Design Results:

• -A tubular, open-truss-structured bike-frame tube that requires less material than conventional solid carbon tubes, reducing material cost.
• -A finished bike frame as stiff as that possible with aluminum alloys, but lighter, stronger and stiffer than solid tubes of carbon composite or other materials.
• -A tube structure that isolates crash impact damage, minimizing the risk to frame integrity.

Tubular composite truss structures made their debut early this decade. Designed and built at Brigham Young University (BYU, Provo, Utah) and trademarked as IsoTruss, this “open-tube” concept starts with the benefits of two-dimensional isogrid structures — made up of the engineer’s most efficient structural shape, the isosceles triangle — and takes it, literally, to the next dimension.

“Isogrid structures were so named because of their quasi-isotropic nature [in-plane],” explains Dr. David Jensen, director of BYU’s Center for Advanced Structural Composites. Jensen coined the term IsoTruss to differentiate the BYU structures from the more traditional isogrid designs. IsoTruss structures feature repeating triangles, similar to the (two-dimensional) triangles in traditional isogrid structures, but arranged in a radial or tube-like configuration in which the triangles form a truss of pyramids that exhibit multiple radial symmetries. The result, says Jensen, is an orthotropic material, which by definition has at least two orthogonal planes of symmetry (with right angle intersections), where material properties are independent of direction within each plane, giving the design performance advantages over conventional solid tubular structures.

Although any fiber and resin combination can be used to make an IsoTruss structure, the concept is attracting attention in the cycling community, where carbon fiber composites have proven their worth as weight savers. The IsoTruss geometry forms what is at once a supremely functional and visually striking feature of custom carbon-composite bike frames built by Delta 7 Sports (Payson, Utah).

BYU licensed IsoTruss technology to Advanced Composite Solutions (ACS, Payson, Utah), which set up Delta 7 as its manufacturing arm for IsoTruss bicycle frames. Delta 7 began production of its Arantix mountain bikes and Ascend road bikes early in 2009, both types incorporating IsoTruss frames in all sizes.

The frame for the road bike weighs in at just over 1,000g/2.2 lb, and the mountain bike frame at about 1,247g/2.75 lb. For comparison, the OCLV 55 tubular carbon composite frame developed by Trek (Waterloo, Wis.) for Lance Armstrong’s 2004 Tour de France Stage 16 uphill time trial, which set the stage for his first-place victory, was 907g/2 lb (see “Editor's Picks”). Finished bike weights are a scant 6,350g/14 lb and 9,525g/21 lb, respectively.

Challenging Forces

Delta 7 composites engineer Ed Packer identifies the biggest challenge in designing and building a bicycle as “knowing what forces are applied on each part and how to properly assemble all the parts together to meet those force requirements.” For example, the top tube must have the strength to manage high bending forces, and the down tubes must maintain strength integrity under torsion loads. Packer explains, “The forces put into the frame are from pedaling the bike, and the more energy that goes straight through the chain to the spinning wheels, the better. A flimsy frame wastes that energy, but high stiffness transfers energy very effectively.”

Force requirements are established for bicycle frames in standards set by The European Committee for Standardization (CEN, Brussels, Belgium). “We also learn about forces in feedback from riders,” Packer says. “A rider might tell us the bike could be a little more stiff in the rear triangle, or other area, and we reinforce that area to meet the need.” While its ability to damp road shock is similar to other carbon bikes, “we’ve had a  lot of feedback from professional riders mentioning our bikes are not as hard on their bodies as other bikes they’ve ridden,” Packer says, “even after a 24-hour race.”

Knowing how these forces will interact when connected through the lugs is a critical design factor. Lugs are the cylindrical sleeves that receive the frame tubes at their joints, strengthening the joints and serving to distribute the stresses over their entire area. Delta 7 designs and compression molds its own carbon composite lugs, which connect the frame elements to each other, and to standard sizes of seat posts and other bike parts. The lug slides over the frame truss tube and over the connecting part in conventional fashion. Delta 7 road bike frames have three IsoTruss tubes and five lugs, while mountain bikes have seven IsoTruss tubes and four lugs.

The frame design is based on data from two stress-analysis programs developed by BYU. Packer explains, “One is a spreadsheet set up with equations for compression, bending, torsion and tension. We enter the strengths we need to handle the forces and the program defines the amount of material and the thickness of the IsoTruss members required to meet those strength requirements.” The other is finite element analysis (FEA) software designed by BYU specifically for IsoTruss analysis. The FEA assesses failure modes in axial, torsion, bending, shear and local and global buckling. Control variables include fiber type, resin system, fiber architecture in longitudinal members and helical members, geometry of the truss triangle, and diameter and overall length of the frame member.

Less Material, More Strength

The open-truss design uses less material than a solid tube — an important consideration when calculating costs — but offers greater strength and stiffness. “The geometry of the IsoTruss turns out higher strength-to-weight and stiffness-to-weight ratios than a solid carbon tube or a solid tube of any other material,” Packer claims. Delta 7 uses 12K unidirectional prepreg from TCR Composites (Ogden, Utah), made using TCR epoxy resin and T700 aerospace-grade carbon tow (from Toray Carbon Fibers America, Flower Mound, Texas). Fiber architecture is typically longitudinal (0°) for tension and compression force, and helical. The helical angles can be customized to optimize strength and weight requirements but, as Jensen points out, the highest torsional stiffness and strength generally will be achieved when the diagonal (helical) members are oriented at ±45°. Packer adds that the IsoTruss is an adaptable concept: “If the bike frame will be subjected to significant torque or other complex out-of-plane loads, we can open up the 45° angle, making a wider angle, and increase the diameter of the helical members to support the complex local bending and torsion forces. Or, if the forces in the members are primarily compression and tension, the helical members are used only to stabilize the longitudinal members, so a simpler ±45° configuration, without additional reinforcement, is sufficient.”

The helical fibers spiral around the edge of the straight, longitudinal fibers in a special filament winder built in-house by Delta 7. It manufactures one truss tube at a time, building up individual rods that range from 2.54 to 3.175 mm (~0.100 to 0.125 inch) in diameter to construct truss tubes that can be 38 to 102 mm (1.5 to 4 inches) in diameter and 152.4 to 508 mm (6 to 20 inches) in length, depending on bike size.

Spider-web Geometry

Packer says that during the winding process, the spider web-like geometry must be maintained precisely until cure is complete. This requires tooling with tolerances of 0.127 mm/0.005 inch. “The longitudinal members need to be held straight and the helical members must be held straight between the peaks,” he notes. (Peaks are the pyramid-shaped sections that extend out of the truss.) “To achieve that, each peak needs to be suspended at the proper distance from the center of the mandrel tooling.” The mandrel, then, must be shaped in such a way that it will hold each node (the peak intersection) securely in position.

At one time, a soluble mandrel was used, which allowed pressure to be applied during cure yet was easily removed afterwards. But that tactic required Delta 7 to cast a new mandrel for each structure. To save time and cost, Delta 7 developed a proprietary collapsible mandrel concept.

While the current winding technique is complex and labor-intensive — and therefore expensive — the company has applied an innovative method of consolidating the fibers during cure that Packer says has taken “probably 60 percent of the labor out of the manufacturing process.” Wound trusses are oven-cured at 127°C/260°F for two hours. Finished frames are physically tested by an independent laboratory for compression, fatigue, impact, bending and torsion to ensure compliance with CEN standards.

Delta 7 sells complete bikes, combining the frame with other bike components selected by the customer, but also offers the frame alone, for those who want to assemble a custom bike on their own. The IsoTruss frame requires minimal maintenance and has a lifecycle comparable to that of other carbon-fiber frames on high-end retail bikes and considerably longer than a metal frame because the composite is not susceptible to rust or other corrosion. Delta 7, in fact, offers a lifetime warranty on the frame. Moreover, the redundant lattice structure reportedly gives the frame greater structural integrity during impact or crash scenarios because, unlike with conventional carbon tube frames, local damage is geometrically isolated, avoiding catastrophic frame breakage.

Down The Road

ACS already is moving forward with its next application for the truss technology: an IsoTruss structure that could be used as a tower for cell phone or other types of communications, or metrology. However, Jensen and Packer agree that there is a need to reduce the remaining 40 percent of the labor-intensive process with a cost-effective automated winding process, the lack of which has been a barrier to rapid commercialization of the IsoTruss and other composite grid structures. BYU and Delta 7 are investigating a process described by Jensen as “an innovative form of 3-D braiding which can continuously fabricate composite grid structures with 3-D surfaces directly from computer models, without geometry-specific internal tooling or molds.”

If its promise is fulfilled, the method could save enough in time, reduced labor and elimination of tooling cost to open up a wide variety of future applications in aerospace, marine and energy markets where, if the price is right, these strong, stiff, lightweight structural trusses could open new roads for composites.

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GRUBER Assist Made No Sale To Cancellara

GRUBER Assist, an e-bike drive train company in Austra, has (fortunately or unfortunately) found itself at the center of rumors regarding illegal motor use among the peloton.

I covered the story two days back and wrote about my feelings of what a motor should be capable of to help someone win the Paris Roubaix or the Tour of Flanders. We took for granted that this motor could be the GRUBER Assist. In the comments section of that blog post, I agreed with posters that at high cadences and power outputs such as Cancellara's (see Anatomy of a Cancellara Attack), the rider can "dilute" this motor, if you will.

Don't get me wrong. I'm also very impressed about the product's capabilities. I suppose one good thing that has emerged out of this controversy is that it is showing people a neat little technology for use in bicycling and potential use in bike racing.

BikeBiz already reported that the motor involved in the controversy in fact comes from Hungary, not Austria where GRUBER is based in. But hey, Hungary and Austria share a border.

Just to get the record straight about the product and its alleged use in the peloton, I had a chat with Julia Timmerer, a representative for the company. The following is what she told me in reply. I quote her :

"We are pleased about your interest in our product.

GRUBER Assist is an ultra-light drive for bicycles, invisible and built into the seat tube of the bicycle. The auxiliary drive supports with 200 Watt engine power (100 Watt Output) and weighs just 900 grams (plus 1 kg battery).

You can store the frequency of the pedals between 30 and 90 rpm. And so it gives the difference to your frequency. For example: You pedal 60 rpm, the motor is stored to 80 rpm, he supports the 20 (as far as it’s possible with it’s 100 Watts). BUT, if you pedal faster than the motor (you pedal 80, motor is stored 60) you overrun the motor and have no support.
For installing the GRUBER Assist into your bicycle, please note the requirements for the bicycle frame:

• - Aluminium or steel bicycle frame
• - Straight, continuous seat tube
• - Seat tube inner diameter of 31,6 or NEW 30,9 mm
• - Shimano Hollowtech II crankset – with outer bearing shells
• - Seat tube should be as central as possible on the bottom bracket
• - Minimum length of 62 cm from the middle of the crank to the saddle or 57 cm at a shorten seat post
• - Installation by a certified GRUBER Assist dealer

On our homepage you can find 3 spots which explains the GRUBER Assist exactly: http://www.gruberassist.com/english/downloads/spot-gruber-assist/

Please note, that neither the GRUBER Assist, nor the battery is admitted in the USA.

Please note, that the GRUBER Assist has not installed a blocking. For example in Austria an E-Bike needs a blocking at 25 km/h, otherwise you cannot drive legal on a public street. If one wants this blocking, the customer should let us know with their order. A later installation is very complicated and more expensive.

We never sold the GRUBER Assist to Fabian Cancellara and we don’t think that one of our dealers did this. And I don’t know anything about the using of our product in any races. At the moment our product is unique and we also have the patent for it. I don’t know anything about a similar product. There are many other E-Bikes (hub dive, bottom bracket motor,…) but those bicycles are not only very heavy but you can also see the motor."

Fabian's race winning bike posted by Jered Gruber. Where's the motor?

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Did Cancellara Use Illegal Motor Power At The Classics?

When I first read the story this morning via a Twitter shrapnel, I dismissed it as an unimpressive attempt at comedy. The story was titled "Former Pro Says 'Mechanized Doping' Is Real."

4 hours later, people were crying "mechanized doping, mechanized doping!" and sharing another story from Belgian source Sporza.

In it, Davide Cassani, an Italian commentator for RAI, implies that pros (like Cancellara) maybe using at races a bike retrofitted with a certain kind of motor. From first impressions, it looks very much like a modified Gruber Assist.

Cassani remarked that if he were given a bike like that at his age of 50, he'd probably win a stage at the Giro d'Italia himself! Among his other claims were that the mechanism has been in existence since 2004 and pros have even used it in the past.

A shady video (below) was then made by "CyclingmanagerItalia", whose real name is Michele Bufalino, showing how Cancellara may have used this device during Paris Roubaix and the Tour of Flanders. Question remains : Who started the rumor about Cancellara using a motor?




The Gruber Assist, the interesting mechanism that maybe at the center of these rumors, happens to be a 900 gram (1.98 lbs) motor-control unit powered by a 1000 gram Li-Mn battery that is placed in a saddle bag from where cables and electronics run. The motor is switched on and off or placed into pedaling frequency recording mode by a button on the handlebar end.

The motor itself is designed to fit inside a 31.8 mm diameter seat tube, thus hidden from view. The drive mechanism appears to be a 90 degree bevel gear arrangement as shown in the pic below. The manufacturer claims that upto 200W of extra propelling power is delivered to the rear wheel at a rated cadence of 60 RPM, with a running time range of 45min-1.5 hours.


A peek at their website yields some specs for the battery. If human pedaling contribution was ignored, the battery has 4.5 A-hours of capacity at 6 A current and 30V rating. What that probably means is that a 6A current will discharge the 4.5 Ah capacity battery in 45 minutes. If the manufacturer's claims are true, the exaggerated 200 Watts could be from :

30V x 4.5 A-hours = 135 Watt-hours or 135 watts for an hour.

Of course, batteries work like human power. The faster you discharge energy from the battery, the less it can totally supply. This is called Puekert's effect. So the numbers above can drastically change with higher energy demands.

So suppose these video allegations from Cassani are indeed true, and suppose the motor was indeed suitable for the famed cobbles of Roubaix and the Kepelmuur (9.3% average, 19% max). What then?

On the hill section where Cancellara attacked dominantly, the motor must have been expected to supply an extra 200+ watts of power for him to power away from Boonen. On the cobbled sections to Roubaix, it must have been expected to provide upto 250 Watts of extra power to counteract wind resistance while accelerating away from the bunch. I'm not sure of the wind conditions, but with headwinds, add another 200 Watts give or take to that figure, for every 5 mph increase in wind speed.

All in all, with the weight requirements that pro cycling demands, the energy demands imposed on the battery are substantial. Not only is the discharge rate very high, such as that asked for in an attack during the race, but the gravimetric energy density (Wh/kg) of the battery must also be high. If the battery weighs 1 kg as claimed, you're looking at a desired supply of upto 200 Wh/kg and over. My first guess tells me that a Li-Mn battery could not meet these racing specific demands. But I maybe wrong given the rate at which battery technology is getting better. See the graph below :



To the lame man, more important questions, however, are the following :

1) How was Cancellara was able to get away from not being noticed in spite of sound from the motor? Observe in the video below the amount of noise this thing makes :



2) Where did he place the 1 kg battery, if he didn't have a saddle bag?
3) The seat tube must be internally drilled out with a reamer for the drive unit to be correctly placed. The drive unit would have to be made to work with the SRAM bottom bracket, as the off the shelf unit only works with Shimano Hollowtech II. After that, all parts would then have to be hidden from view, given the number of components in the assembly as shown.


Surely, if this event took place, someone knowledgeable in how to do all this would have assisted at the Saxo Bank camp.

This may either be a good one for the spoof books, or something just so good that it doesn't appear true.

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Design Case Study : A Recumbent Bike For Patients With Cerebral Palsy

It is quite often that we observe cycles becoming a platform for design and study ideas, especially at universities. Perhaps it is the simplicity and access to the structures and parts of cycles that make it popular for such use. Students choose bikes to explore the physics of riding, or torque and power relationships; they like to mount motors on them to establish drive capabilities, or generate electricity using pedal power, or automate it using various mechanisms and so on to put it to different uses.



Last year, I wrote about Alfred University alumni creating a hotdog launcher using a bicycle. In February, you may recall how I wrote a bit about Yale students building a spokeless wheeled bike. Keeping with the theme of bikes for design projects, this week we explore the work of a team of students from Michigan State University who took a recumbent bike and engineered it for the use of patients with cerebral palsy. The work was sponsored by GM and the MidMichigan Medical Center.



Senior mechanical engineering students Spiros Kakos, Eric Wickenheiser, Drew Darling and Marshall Mendoza were inspired by the Nu-step exercise machine and desired to mimic it's design elements into their bike. That said, their engineering time was predominantly devoted towards creating an electromechanical steering system in order to present a safe and convenient interface for patients.



15 weeks of hard work later, they had a successful design. Just last week, it was publicized by a local TV station and unveiled on the school's 'Design Day'. They were all smiles as they presented their mobile recumbent bike to Peggy Essex, a physical therapist assistant and their liason at MidMichigan Medical Center.



Obviously, creating designs for physically challenged people is not an easy task as these are not your everyday users. I had a chance to chat with Spiros and shoot him a few questions about the bike and what their work comprised of. In reply, the team was quite forthcoming in sharing information.



Presented below are lots of pictures and tables to look at along with material to read !









1. This rehab bike project was for a senior design class I take it?



SK : Yes.





2. But how is it that you were working on it for four years?



SK : Our design team hasn't been working on this project for four years. We are just the fourth team to work on project. The teams before us have failed in completing the recumbent cycle. Each generation of the cycle has gotten better, however; our team has successfully completed it this year.





3. Forgive my ignorance. Now this bike of yours has a solid clinical purpose behind it. How did you define this purpose at the initiation of the project?



SK : The purpose of the cycle is to help patients with neuro-muscular diseases perform cardiovascular exercise outside rather than inside the rehabilitation center. The goal was to provide these patients with a more fulfilling and enjoying workout.

Engineering projects typically involve outlining a set of goals and ranking desired features, materials and other details based on distinct attributes.

4. What objectives did you want the bike to achieve and were you inspired by something in your journey to make it?



SK : Our main goal on the project was to design a functional steering system that would allow the patients control the cycle with ease. We chose a rack and pinion design because we were impressed with its reliability.





5. Great! For readers here, talk a little about the highlighting features of the bike such as source of motive power, brake systems, controls, and so on.



SK : Well to highlight some of the features, it has electric steering. A battery powers a motor to turn the rack and pinion a certain direction once a button on the arm handles is pressed. The cycle is powered by the arms and legs of the patient in a "push and pull" motion.



From just talking with Peggy Essex from MidMichigan Health Center, it was found that children with cerebral palsy have decreased muscle strength, muscle spasms, decreased range of motion, and poor or altered posture control. This suggested that the design of the recumbent cycle needs to be efficient in generating propulsion from the energy exerted by the patient. Also, a push pull system gives a better advantage to the patient rather than a rotational propulsion system, because of the limited range of motion in the patient’s extremities.

The Nu-Step propulsion system helps utilize energy from both arms and legs simultaneously.

Previous teams had standard lever arm steering. Integrated rack and pinion improved functionality and durability.

The input power is transmitted to a couple of gears that have one directional bearings which then rotates the chain to propel the cycle forward. There are disk brakes on the two front wheels which are applied through a cable after squeezing the arm handles. Unfortunately we only had access to the previous teams' design reports and pictures so it is hard to describe the changes from before that. But the "re-design" in steering basically encompasses a much more reliable and stronger system. The design of steering in the previous year contained a servo motor that was insufficient and a motor that did not have enough power to turn the wheels. This caused the teeth on the motor to skip and grind down.



The rack and pinion was controlled by a DC servo motor that was mounted to the frame. The DC servo motor is operated with two push buttons that were installed atop the hand grips located on the handle bars. The location of the push buttons was determined with the help from Peggy Essex, the professional assistant at the Mid-Michigan Medical Center. It was important to place these buttons where they could be easily operated by the patients.

The two front wheels are connected to a rack and pinion. The shaft of the rack and pinion is attached to a motor. Rack and pinions are effortless to use, self steered, reliable, and allows smooth steering without interfering with propulsion.

Design using tools such as ANSYS helped increase torsional stiffness and overall strength on the frame. The frame was made from steel which made welding additional brackets and parts to the frame easier than aluminum and created a stronger bond. The frame was circular in shape and had dimensions of 35in. x 22in.

A new cam support was designed to allow for smooth propulsion at greater torsional stresses.

6. Now that this is over, would you consider the project successful?



SK : Yes definitely. We are very pleased with the outcome.





7. Your customers are the folks who have these physical challenges and indirectly, the medical staff as well. What do they have to say about it?



SK : We have only tested the prototype on fellow students so far but everyone seems very excited to try it out. The steering is so easy and everyone we talked to seems to like the overall aesthetics.

Since this cycle will be used for people of all shapes and sizes, a wide range of people were asked to use the cycle. The table below gives the results. The height and weight was recorded for these tests. The person was then asked about how comfortable they felt and how easy the cycle was to use once they adjusted the arms and seat to a position of their liking. These values were also recorded.





The electromechanical steering was one of the most challenging aspects of this project and testing its usability from the patient's standpoint was very important. With the help of our advisor, we were able to rank how easily a patient could operate the cycle. The table below displays these results. A ranking of 5 for Disease Case means a very extreme case of neuromuscular disease, while a rank of 5 in Ease means supreme functionality of the user and the push button on the handle grip.





The table shows that the very serious cases of neuro-muscular diseased patients have a harder time with the push button system our team incorporated. However, our design is still successful overall. Patients with less severe cases will still be able to enjoy their cardiovascular workout.





8. Time, money and materials. How many man-hours do you estimate you put on this, and what were the main tooling and processes you used?



SK : I would say that each member of the team put about 25 hours a week of work into the cycle. We used many different machines, but the main ones were band saws, belt sanders, and welding. We built the cycle in-house at a shop owned by Michigan State University. None of the work was outsourced.



Each of these machines served a purpose for the creation of each part used on the cycle. To minimize time spent on manufacturing each part through trial and error, a NX prototype served as a very useful tool in seeing how the assembly would mesh and operate without any manufacturing. This enabled the team to create parts once; mounting them to their position without any alterations after being initially fixed.







9. Give us an idea of the people and organizations that helped you in this project.



SK : The cycle was basically built by the team. General Motors was our project sponsor but they only supplied the budget for the project. We also had a faculty advisor who helped us in coming up with ideas and computer modeling. Otherwise, everything was completed by our team of four students.

10. What engineering lessons did you learn, if any, from this endeavor. Do you guys feel there is a future for the design?



SK : Personally I learned a lot about manufacturing and control systems. This project did cover a huge range of engineering principles and required all of the team to brush up on previous knowledge. I do believe there is a future for this design. It's a start. I'm sure there will be other ways to perfect the cycle in the future, but showing everyone the answer to a solution will hopefully spark some excitement in making it better.





11. As time goes, new needs come about. What suggestions do you have for future work?



SK : Some improvements would require a better belt tensioning system. It tends to come lose every now and then. Also, the arm handles are heavy and shifts the cycle's center of gravity from where it should ideally be. If it were made of aluminum instead of steel, I'm sure this could be resolved.





12. You guys were obviously inspired by a recumbent bike to help these patients out. What do you think of bicycling itself as activity for recovery and rehabilitation, compared to other impact bearing activities?



SK : Fortunately, I have never needed rehabilitation for an injury so far in my life, but I think cycling in general is a great way for someone to recover. The impact on joints, such as knees and ankles are minimized compared to jogging or weight lifting. Overall, it was a very fulfilling experience for the entire team.





13. Do you have anything personal to tell people with physical injuries and disabilities?



SK : Our team has gained respect for the people dealing with such a disabilities and how many hardships they must overcome within their life.



I would like to say that technology in this field is taking off so fast. From where I see it, there will be a solution to many disabilities in the near future. So I would like to tell people with physical challenges to be patient and always keep their heads up.

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