15 Crank Brothers Candy C Pedal Failure : 2

Those Chinese made Crank Brothers Candy C pedals, whose flaws we discussed in an earlier post, has obtained another victim. The pedal failed in the same area again. A reader, who describes himself as a relatively non-litigious person, emailed me his story with pics of his injuries along with the broken pedal spindle. He describes this as a serious design flaw and wrote that had he crashed while going downhill at speed instead of the top of the hill he was riding on, he may not have lived to tell the tale.

Some good people had noticed his crash and rushed to get him to a hospital. There, he would find out that he had broken his right clavicle in two places, not to mention extensive bruises and abrasions. "It hurts like hell, inspite of Vicadin", he wrote. The healing process takes 8 weeks, or 2 months. How would you feel if your summer was ruined like this? We do hope him a quick recovery.

Fatigue is the biggest limiter of products whose design goal is to take cyclic loads and is often the prime reason for failure. Overlooking the design or manufacture of such items to combat accumulated fatigue leads to reduction of its life prematurely, that may result in serious injury or death. A rough back of the envelope calculation of mean and alternating stresses in a pedal spindle was done by me in the previous post for perspective.

Simply relying on safety factors alone does not take care of this important issue. The synergistic effects of product design geometry, heat treatment, loads imposed, environment, residual stress and time can all reduce the lifetime of a product. It is common practice to see companies show off their computer skills with exquisitely colorful FEA. This is not the end to the fatigue design process either. Verification has to be absolutely thorough. If you don't test the item, which is for public use, by simulating real world conditions, you can be held guilty of negligence.

This is the flowchart that the SAE likes to follow for designing against fatigue. Observe that the word "modify" shows up in three different spots.

How safe do you want to be? I hear that something like one major air accident everyday is considered a 99% safety rate as far as air travel goes. Anyway, the company Crank Brothers has babysat the individual in question with a new pair of Candy C's. Everything is safe. Don't you worry, here's a band-aid. This was just another outlier.

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19 SRAM Force Brake Housing Failure

I had written a post a month back reviewing the story of a SRAM brake lever housing failure, belonging to an individual who maintained that when his mechanic called SRAM to find out what the issue was, the reply came back from the SRAM employee something to the like of  "oh yeah, we knew about that, you know...we injected some extra air in the part during molding...." SRAM didn't inform consumers that this incident had happened in the manufacturing phase and let the product sell. The brakes cost almost 200 dollars in retail value.

The comments in that post were also interesting. You should really read them. One individual who is an ex-Ciamillo employee wrote to me that something very similar in substandard manufacturing practices was happening with the highly expensive Zero Gravity Gravitas brakes. He was frustrated with the owner, who felt to him like all he wanted to do was produce more brakes without a care in the world for people's safety. He left the company shortly. Now those brakes sell for a staggering 875 dollars a pair!

Anyway, the story about the SRAM brakes is not a mere anecdote as now more pictures are coming in. So I thought I'd follow up on that last post.

Now the same housing failure happened to two other people. The power of my blog lies in being able to connect people's experiences across the world. One individual saw the post here in the U.S and wrote to me recently :

"The SAME thing happened to me! The plastic cover just shattered, a piece of it shot across the room. It was so odd. 20+ years of working on bikes and I’ve never seen anything like that."

Here's an image he sent me :

Another individual in Ireland could also relate to the incident. He had a similar nightmare with his SRAM gruppo, documented here. The characteristic housing failure did not escape him either.

"Brake cable goes inside the clamp, I adjust the brakes to where I want them. Put my torque wrench up and start twisting when pong!, something goes flying. Immediately I start scanning my torque wrench thing, crap I’ve broken my torque wrench. But no, the brake quick release housing has decided to give up. Firstly, the manual says tighten to 6-8nm. My torque wrench was set to 5nm. Yes I know it was light but I’d rather be safe on the initial setup of things, so I usually do a lower torque first then go back. Well in this case it didn’t matter."

 

Here's the image he referred me to.

The attitude the company has to such incidences is also interesting to learn. According to a blogger who raised this issue on their website, a SRAM public relations rep tracked the post down and allegedly barked at them via email, "Why are you talking such nonsense about plastic QR's breaking? The brakes still work. Please take the post back, people understand this is not a problem." 

I see. Without letting people know about the problem, obviously their understanding will be that its not a problem!

Please be aware of this issue and contact SRAM with your concerns. If they do not redress your problem, just shoot me an email and I'll try to help.

CONNECTED READING :

Defective SRAM Brakes Not Recalled

*  *  *

30 Defective SRAM Brakes Not Recalled

This story is an interesting one and if true, shows how certain bicycle companies, as I have always believed, are negligent about customer safety or educating people about the same. I already proved a few months back how Shimano displayed this attitude with their Ultegra chain issue, which snapped and caused a serious safety concern for many riders yet they did not issue a recall. Its not just me who holds this belief. Notable personalities like Jobst Brandt and Professor David Wilson believed it. Its not going to erode away easily.

Last week, a reader of my blog, ordered a pair of new SRAM Force caliper brakes for his road bike. As you may know, SRAM revised the design of these brakes recently as the 2010 version has a gunmetal finish to it.

When his local bike shops’ mechanic went to install the first brake calliper, the quick release lever housing broke in half. Surprised, the mechanic then proceeded to install the other very carefully - you know - being cautious not to twist the housing when he attached the cable and careful about torque and all that.

Nevertheless the other one broke in the exact same way. About a third of the lever and the housing around the lever snapped off in both brakes, leaving a weakened part behind. This plastic housing is directly connected to the brake cable attachment point, something that could be a serious safety hazard. No brakes, no safety.

The mechanic told the reader that he had called SRAM and asked about this problem. To his utter surprise, the person answering the phone actually said :

"Yup we’ve had a whole batch of bad ones. They injected too much air when they molded the part.” 

It is a bit strange that SRAM, having complete knowledge about the defect, chose to still ship the parts to their various distributors and haven’t uttered a word on the issue or recalled the product. This is inexcusable and unethical!

I'll leverage the power of my blog to get responses from you readers. Please be aware of this problem and take action but while we're at it, have you experienced any similar issues? Please report it here and please feel free to be honest about your thoughts.



CONNECTED READINGS :

A Petition To Bicycle Companies On Safety Of Products

15 Speedplay Light Action Platformer Failure

One of the tricky aspects to catch in product design is the amount of true value in it between its stages of evolution. Sometimes, last year's model that you bought could have negligible difference in it as opposed to this year's. Its marketing might say its improved, with a new recipe, new look, new shape and so on and in the end, you would probably pay a premium for it as well, all for the same exact thing.

On the other hand, as a credit to product design, it could also be that last year's model could be insufficient for use compared to the current year's release. Dangerous too. So is this really a credit if people are still using last year's product?

Subsystem design is very dependent on the performance of the parent system.  Today's illustration is a case in point.

Speedplay's marketing line for the "Platformer" brand of pedal adapters is this : "The innovative Speedplay Platformer is a user-friendly, tool-free platform cover for Zero and Light Action pedals. The Platformer makes it easy to convert from clipless pedals to platforms for riding with street shoes."

But reality is different. Last year's clear "Light Action" pedal adapters are really light action, apparently.  As the internet will show, quite a number of people are disappointed with the quality of material used in its design. Durability issues notwithstanding, riding your bike with one of these installed could be a danger just waiting to happen

Among the disgruntled is an individual (who doesn't wish to be named) whose adapters broke just as he was pulling out of a traffic light last summer. Casual riding wasn't light enough for Platformers. The plastic adapter on his right pedal broke catastrophically with an audible snap. Because of little warning, he lost his balance very quickly and ended up crashing on his tailbone and elbow, right in the middle of a road during rush hour traffic. A crucial red light to one side gave him enough time to get back up in pain, pick up the pieces and vacate the road.

Thanks to light action pedal adapters, he is in miserable condition today. Because a fractured coccyx is an injury with no form of available treatment other than time, five months later he still is in immense pain on a daily basis and can’t sit for more than an hour without feeling discomfort. He calls the sensation "intensely searing". For the weekend racer and an enthusiastic bike geek that he is, this is not exactly the good life.

The gravity of the injury and the possibility that someone else could be hurt in similar fashion made him contact Speedplay on many occasions. To make sure this wasn't some freak event, he even installed a set of the old Platformers on his girlfriend's bike as well. The product lasted approximately 16 minutes before they cracked. Some insults are better off when they come with forewarning. This one was even recorded on video by him.

Speedplay took back his pedals for inspection and has stuck by the quality of their brand. They chose to deny his theories of why they broke and didn't feel much need to return them back to him. They have claimed no responsibility for his injuries and other damaged personal articles. The user has now fixed a date with a Small Claims Court to settle the matter in the interest of full disclosure. He has also had a meeting with the Consumer Product Safety Commission.

Interestingly enough, this year's design, with the new "recipe" doesn't seem to have had as many problems since it does not use the same plastic clamshell (see right). The user ordered a pair from Competitive Cyclist, rode them on his girlfriend's spin bike for 50 minutes (the approximate lifespan of the broken ones) and they seemed to hold up just fine.

I suppose somewhere, someone found out the trouble with the old pair, fixed it, moved on. Meanwhile, old units are still being used by riders.


A Plausible Theory

The concept behind the Speedplay Platformer is to allow the user the option of riding a bicycle equipped with Speedplay brand pedals without having to wear dedicated cycling specific shoes. By creating a larger, stable platform around the pedal, Speedplay Platformers, allow the user to ride in “regular shoes."

A set of Speedplay Platformers consists of six pieces. A complete, individual unit is comprised of two seemingly identical pieces of clear plastic. The difference between the two pieces is found on the “inside” where four tabs fit together in a male/female manner. A metal retaining clip slides through these tabs and locks the Platformer in place around the Speedplay pedal.

Because of this design and the fact that the Platformer is molded to be compatible with only one specific type of pedal, it is virtually impossible for the Platformers to be installed incorrectly. They are either locked in place or they aren’t and this is very obvious to the user. To remove a Platformer, a key, coin, or screwdriver is used to remove the metal retaining clip by sliding the clip from the Platformer. The edge of each Platformer is concaved to facilitate the easy removal of the retaining clip.

At the time the user tried the product, he was 210 pounds and stood a height of 6'1". While this isn't typical of your featherweight climbing maestro, he told me that he's never broken any products before and he's always careful with cycling equipment.

Now clipping in and clipping out of Speedplay pedals cause substantial wear on these high performance pedals as most of us have learned. The right pedal, more so due to clipping bias in start-stops. The user's had between 3000-4000 miles of usage on them. For most people, this is a season's worth of use.

This leads to a plausible theory for why the pedals failed. He wrote to me :

My theory for why they broke is because design of the Platformer didn't take into account worn pedals as they are molded around a brand new set of pedals. Since the pedals I was using were worn down, there was some open space between the Platformer and the pedal itself which lead to much more stress on the Platformer particularly on the "outside." 

The following two images show a  3.2% reduction in right side pedal dimension between a brand new and the user's old one.

New right pedal

Used right pedal

The following image, of the used left side pedal, shows a 1% difference in pedal dimensions when compared to the right side pedal. This shows that the right pedal wears more due to clipping bias.

Please be aware of this problem and report any of your personal mis-happenings in the comments section. If you also wish to offer any kind words of advice to the user with regards to a broken tailbone, please share your thoughts.

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32 Crank Brothers Candy C Pedal Failure

A reader who doesn't wish to be named sent me an email with this image. What is shown here is apparently a right side Crank Brothers Candy 'C' pedal that failed on an indoor Revmaster stationary bike. Good for him it was indoors, and the fact that the bike is built with safety features for holding onto something when falling in embarrassment.


The user estimated that he would have put a little more than 100 hours of time on these pedals, all during home use at fairly low pedaling intensities. He is a fairly big person, at 6'2" and weighing 217 pounds.

When it broke, he had been standing on the pedals for want of some variation and was putting forth moderate effort. But he remarked that despite cycling since the 1980's, this is the first pedal he has ever broken. He has other Crank Brothers pedals in stock for outdoor riding but this event has diminished his confidence in those as well. Natural.

The pedal features a chromoly spindle. I do not know its geometrical specifications. Curious enough, I visited the Crank Brothers website (its very well developed actually, so Kudos to them!) and obtained a screen-shot of the spindle from one of their servicing videos. The failure, as I see it, happened just where the cross section started to step down :




Loads & Stresses : The spindle acts like a simplistic cantilever beam with the concentrated reaction force R and pedal force F as I show below.


Then, for a solid spindle acting like a beam, maximum shear stress at the neutral axis would be about :


where V is shear force and A is the cross sectional area of the round section.

By looking at the length of the spindle above compared to its depth (L>>d), one might be able to say that what would be more concerning than the shear stress itself is the spindle's bending stress at one or two critical locations (sites where part sees high stress risers). The designer would then multiply the concentration factors necessary for these stress risers to the equation for maximum bending stress at the spindle's outer fiber given by :


where c = outer radius of section, M = bending moment & I = moment of inertia

High Cycle Fatigue (HCF) : Since the user told me that he uses this moderately at home, the correct technique to analyze the spindle would be in HCF, in a mode of fluctuating loads. Here, the stresses seen would be much below the yield of the spindle material but the loading would gradually accumulate until failure. This happens because of local yielding at critically stressed locations.

To generate a rough idea of fluctuating load on the spindle, I made some assumptions. Research has shown that a good figure for average pedal force for long periods is about 1/5th of body weight. If this is the average, then an approx. max force could perhaps be 75% of body weight. So for a 217 lb person riding moderately like the individual here, a possible range of forces could be as follows :

Fig.1 : Peak forces are seen roughly when the crank is forward, 90-100 degrees past top dead center. These peak forces are a resultant of effective force (radial) and ineffective forces (tangential). For specific illustration, mean component of foot load, Fm, is 43.4 lb and in tension. The alternating component is given by Fa = (Fmax - Fmin) /2 = 119.4 lb. Mean and alternating components of the reaction force Rm and Ra is same as for the foot loading forces. Time period is given by t = 1/frequency. Note : Blue region for upstroke has been exaggerated whereas in reality, peak magnitude might not be so high.

The shear and bending stresses can then be derived from these alternating and mean loads. A Von Mises stress calculation can be done for both alternating and mean stresses. These V M stresses can then be plotted on a modified Goodman diagram along with the corrected endurance limit and yield strength to check visually where in relation to failure boundaries this pair of stresses lie. The safety factor of the part in service comes specifically due to how this pair of stresses vary with each other.

Since the material is steel with a knee in the S-N diagram, a good estimate for design pedal life for infinite life in steel would be a capability to withstand the maximum stresses shown in the figure above for 2 million cycles and over. A normal 90 RPM cadence equates to 1.5 Hz frequency or 1.5 cycles/second. So a designer can make a pedal spindle with chromoly to sustain itself for the range of life shown below.

2 million cycles / (1.5 cycles/sec) = 1.3 million seconds = 370.37 hrs.
200 million cycles / (1.5 cycles/sec) = 133.3 million seconds = 37037.03 hrs.

If a company has the time and money, they'll design for higher life than 200 million cycles.

The point I'm trying to make here is that given the rough loading curve for one rider above you, the actual pedal spindle would have had to be designed to withstand much higher amplitudes of stress cycles for many different riders across a broad spectrum. This should also arrive after providing for fudge factors to account for geometrical & environmental influences!

However in this case, the spindle locally yielded at lower stresses in a matter of 100 hours of life to failure. This was in a controlled environment. This does not correspond suitably with the range for HCF life calculated. On the surface, it appears the spindle might not have been designed/manufactured properly which brought down the strength of the spindle considerably from its predicted life.

What do you think? Should the pedal spindle be beefed up in size to accommodate heavier people, designed with milder cross-sectional variations or heat treated appropriately to overcome this dangerous scenario? And what are your experiences with this particular pedal?



RELATED RESOURCES :

4130 Normalized Steel Alloy Material Properties
Spindle Shear & A Related Injury
Falling Out of Love With Crank Brother's Pedals
Integrated Sensors In Intelligent Bike Parts
How A Clipless Pedal Works

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20 Update : More Shimano Ultegra Chain Failures

Pardon me for the pun, but a chain of people have been linked with Shimano chain failures.

Consider this an update to the my first post where a reader alerted me to his concern that large batches of Shimano's Ultegra chains have been failing recently. The said person worked for a cycling magazine so he was probably witnessing this first hand with his access.

In that post (click here if you haven't read it), readers and me agreed that a possible suspect may be related to heat treatment that may be causing the links to become brittle. However, at this point, there's insufficient test data to back that thought.

As to what the heat treatment protocol it is that chain links undergo is not within my knowledge. If there are industry insiders reading this who want to help provide insight, please feel free to join in with a comment.

Within days of writing the post, I obtained news of more instances of failure.

Case 1 : This Shimano 6700 chain, used by Roger failed after just 2500km of use. He wrote to me that he had kept it well lubricated and had never cross-chained excessively (and never with force), yet it broke in the exact same manner as in the images that were shown here. According to him, he had never broken a chain before and would usually swap them out only after 10,000km or so. Apparently, he had them sent back to Wiggle and when Shimano was contacted about it, they didn't recognize the problem.



Case 2 : A blogger with Team BBC in Baltimore, Maryland posted a tweet showing his Ultegra chain that broke in a matter of just 7 days. According to him, it was installed as per the instructions yet he was caught by surprise when he found cracked side plates while lubing the chain today. He also remarked on Twitter that another racer from the same area fell and lost some skin after his Ultegra chain broke while he attempted a "track stand". The following pictures were posted on his blog.





Case 3 : I received a quick note from Jonathan Judd yesterday telling me his story. He did not have any pictures for me. I quote him :

"My Ultegra chain broke 25km into a ride on Saturday. That was the first ride the bike had ever done - brand new. I had climed for around 300 meters in altitude gain without any problems. It was after the descent when I dropped onto the small chain ring (under virtually no pressure) that the chain broke. Initially I thought it had over shot the small chain ring but then I saw it hanging down into the road. Luckily I had a chain tool and spare connecting pin. But 25km is shockingly poor!"

Shimano has not recognized the problem nor have they issued an official statement in spite of multiple failures. It is suggested that they do a root cause study and issue a recall of product from the market if it is defective.

* * *

78 Shimano Ultegra Chain Failure

New "Equipment Misbehavior". A reader from the Netherlands (who wishes not to be named) alerted me to his concern that lately, a large batch of Shimano Ultegra chains (CN 6700) have been breaking with use. These chains are narrow and lightweight, meant for performance riders. I'm not aware of what its roller diameter, plate width etc are. Can anyone help us here?

Anyway, so he was personally riding a steep cobbled climb last Thursday when his chain, 700 kms old, broke on one side of a link. Interestingly, he was able to get home and install a spare new 6700 chain as replacement. Well, guess what. A little after 7 hours and 220kms of riding over Saturday and Sunday, that chain also happened to fail. That's not a good thing to happen to someone who's stranded in the middle of nowhere.

He decided to call Shimano Europe and found their response to his problem as quite rude. In his own words :

"Shimano is still denying the problems, but many people have problems with the 6700 chains. I spoke to someone from Shimano Europe on the phone this morning, which wasn't pleasing since he was quite rude. For me it is not about the money, but all about the risk. The question is if someone is going to crash because of these breaking chains, when and how many crashes are there are going to be? Often there is quite a lot of difference in customer support between Europe and North America. For example Zipp seems to have a great service in the States, but in the Benelux it simply sucks. But the attitude of Shimano seems to be bad everywhere. "

He examined the first chain he broke and found 15 different cracks all over the place. The second chain he broke had 11. He's having the chains sent to another company, who will then X-ray examine them for deficiencies. As and when I get any more news on that, I will post it here.

Notice the interesting manner of crack formation at the two ends of the chain

Now roller chains are reliable over a wide range of temperature conditions. So if the Netherlands has had a really bad weather this year in terms of winter and salt on the roads, should it matter if the chain is well maintained? The individual who contacted me reported that he regularly washes his chain in plain hot water to get rid of salt.

As to the question of whether he applies any other chemicals to the chain for cleaning, I do not know. Shimano does protect their bottom to some extent by calling out the following in their technical instructions.


For chains to avoid breaking in fatigue, the operator has to restrict stresses to those below the corrected endurance limit for the material. The total load in a chain is a sum of the tangential driving force, centrifugal tension in chain and the tension in the chain due to sagging.

But even still, a chain should NEVER break. The only evidence of deterioration in a chain should be elongation due to steady wear. But that usually happens only after 1000-2000 hours of usage in well lubricated chains. They should be pretty reliable otherwise. For a new Shimano chain to break in 7 hours may point to something unassured in its design/manufacturing.

Have any of you experienced similar problems with these chains as well as Shimano's deteriorating customer service?



RELATED READING :

Campagnolo 11 Speed Chain Failure

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19 Look Ergopost Seatpost Failure

When you buy a $250 product, nothing in that price tells you that it will last. This is a fallacy bike consumers often go through in their minds. Is high price = safety & quality? Not necessarily.

This $250 "Ergopost 4" didn't last 10 minutes, according to a reader who emailed me his disappointing story. What's more, this is the second seat post he's broken in exactly the same location. The first one was a Look Ergopost 2Ti which lasted him an unsatisfactory 2 years. For appeasement and warranty honor, he received the "10 minute" Ergopost 4 from Look USA.

The product, by design, appears to be a monocoque setback post with weight of 170 grams and allowing 60 mm of fore-aft adjustability. I haven't seen this in person but Richard Feltner from Florida (the user) told me that while shining a light onto the post, he made out what appeared to be a two piece design with an upper "casting" or "forging" of CF joined to a tube section.

The catastrophic failure happened a little below the setback curve and internally, this is where Richard spotted an intersection or joint between two sub-assemblies that make up the post.

When he had initially received the Ergopost 4 from Look, he had made sure there were no scratches, cuts or deformations as stress risers before installation. He had then installed the post in neutral setback, adjusted it and torqued it to specs using the same OEM collar clamp that Look specially recommended.

Setting his 170 lb self on the bike, he went for a ride on the back streets of his residence. To his utter dismay, within 10 minutes, he heard the distinct crack. The saddle started rocking. The instantaneous cadence increase it brought along confirmed to him that the post had broken. He had to ride home standing on his pedals.

Richard contacted Look immediately who promised him, say what, a third post of the same variety! Apparently, Look has had him in the clutches of their word, assuring him that this is the most bulletproof item they manufacture. He doubts it after two unsafe experiences.

Check out the pics of the strong breakages. Meanwhile, if any of you readers have the same seat post, please fill us in with your honest experience of the product. If others have had similar issues, feel free to tell me about it through a comment. This will be helpful to Richard and a lot of other users. No one wants a seat post forcefully stuck into the rear end.

To Look Cycle : It's time to start "looking" into this issue.


Look Ergopost 2Ti (Richard's first seatpost)





Look Ergopost 4 (Richard's replacement under warranty)









ADDITIONAL READING :

Thomas Masterpiece Seatpost Failure + Mechanics Of A Seatpost Clamp
AX-Lightness Daedalus Seatpost Failure
Breaking Look KEO Pedals
Inspection Of Dave's Carbon Fiber Road Bike

* * *

5 Edge Composite 68 Carbon Wheel Failure

Our protagonist, the author of a blog called "Manley Man", had recently participated in Levi Leipheimer's GrandFondo ride in California. Among the highlights of this ride are really steep descents, some of which feature blind corners.

One of these, called Meyer's Grade Road, was an 18% grade technical downhill and the Manley Man was being pretty cautious going down this road, hitting his brakes every now and then (okay, 'every now and then' maybe a huge assumption from my side). Yet, towards the bottom of the descent, he found things out the hard way. Observations were described thus :

"Toward the bottom third of this descent I felt a very bad pulsation in the front brake lever. I looked down at the front wheel to see if there was something wrong but there wasn't anything visibly bad. But it was scary to see the fork flexing back and forth under braking; it probably was oscillating at least an inch when I had the front brake applied heavily.

I got to the bottom of the descent and my teammate pulled over a few seconds later to see how I was doing. I spun the front wheel and it got stuck. It wasn't clear to me what happened. I opened the brakes up to let the wheel spin more freely. At this point I saw the issue. Initially it looked like the sidewall of my Rubino Pro had bulged out and was rubbing the break pads (yellow Swiss Stop). But to my surprise it actually was a deformity of the braking area of the rim! I had somehow managed to melt the carbon!"

Here's the deformed wheel, picture courtesy of Manley. The original specs of this clincher can be found on the product page. Because its a clincher wheel, the carbon braking track has to withstand the pressure inside the tire.

Manley Man limped through the rest of Levi's ride, being able to use what he estimated as only 10% of his total front braking power. He says that he'll be on the phone with Edge Composites having a long talk with them.

This kind of scenario has been a common topic of discussion on this blog and forums. If you'd like to get a little deeper into rim heating during braking, please see this past article. You may also notice that these kind of incidents happen not only with amateurs, but also professionals on the international stage. See this article.

Now we're all really really wondering what Edge Composites told the owner of the wheel. Will they have it replaced under warranty or pass on the blame to him with no gifts? Manley?

Do you want to discuss the specific nature of this failure? Please include your comments below.




ADDITIONAL READING :

Clincher Failure On Meyers Grade
Rim Heating During Hard Braking
Tubulars Exploding And Peeling Off
Bizarre H Plus Son Rim Failure In Japan

* * *

26 The Machined Death Of A Water Bottle

Sometimes, peculiar things happen to us. And we like to report it. Today's peculiar story to you is a minor tragedy to me. And there's an interesting causality to it, like all events in the world around us. Let me briefly show you causality.

I had a desire to ride my Trek T1 fixed gear bike for 2 hours today. I had an appointment in the afternoon so I was in a hurry to get out of the apartment in the morning and complete the ride before then. So I donned my cycling spacesuit and filled a single Camelbak Podium with some plain orange juice, sticking it into the seatpost's water bottle cage made by Profile Design (injection molded nylon/fiberglass).

Anyway, so I head off for the ride, cruising at a good cadence on 44 x 18T gearing. The road I usually start off riding on had some construction work on one side of it today. The modest traffic was being diverted to the other. I maintained my pace but rode over two unexpected depressions in the road. I believe those people were making road bumps of some sort and I take it that they usually begin life like that - a half done, torn section across the road about 10 inches wide and 1-2 inches deep before they're filled in with a mound of asphalt (??) I faced an uncomfortable, jarring ride over those two, risking a flat. Boom, and then... boom.

20-30 minutes later, I arrive at a local park slightly out of breath and decide to sip some of that juice. Now I have grown so used to grabbing the water bottle from out of the seatpost bottle cage that I usually don't fumble much and don't give it a second thought. This time, surprisingly, my hand couldn't grab onto a bottle. Hmmm....was it still there?

I get off the saddle to check where my bottle was. Yes, the bottle was there alright, but it was a strange sight. It looked exactly like in the second picture below, reproduced for you after I returned home.

This is how I remember having placed my water bottle before heading out of home to ride.

This is how I found it in the park.

Whoa, whoa, what's going on here. How did that happen?

Let's see. If you were really observant, you'd have noticed 4 different things from the above picture. Atleast I did in the park when I got off my bike to inspect my water bottle. Yet, they are all connected. We will then tie a common thread across them and look at causality. Let's look at the picture above again.


1) The bottom of the water bottle was finely touching the rear wheel and tire. No wonder I couldn't get my hands on the bottle. Its perplexing that I rode my bike for 20-30 minutes with a bottle touching my tire.



2) There was a pronounced crack on the upper stem of the bottle cage. Hmmm?



3) One of the two fastening screws of the cage is missing. Ahhh. Okay, so now we can tie a thread across 2) and 3). It perplexes me as to how and where the screw might have popped out. I cannot answer that with certainty. It may very well have been that I started off the ride without a screw and I hardly noticed it, which is even more perplexing because I'm observant about these things.



4) And finally....holy Vitamin C! My orange juice. Its....its...gone!



Can we tie a thread across 1) and 4)?

Well, it turns out we can. Let me show you the underside of the bottle. Look closely.

The tire machined away a small section of the bottle. All the orange juice quickly escaped through it, leaving absolutely nothing in the bottle but some orange soup with road grit.

I have been trying to come to terms with how this happened. Here is a plausible theory, supported by observation :

The density of orange juice with pulp is more than that of water, about 1.2 to 1.25 g/cm^3. Because I was missing a screw in the bottle cage, the weight of the bottle stressed the plastic cage so much that it cracked the stem and compromised its holding strength. When I rode over two significant depressions in the road, the bottle slipped out of the lower base support and contacted the wheel and tire. I was riding at about 17-18mph so the tire, with a certain angular velocity determined by the gearing, started rubbing away at the bottle, producing friction and heat. Some of the juice started leaking out of the micro-hole. As the orange juice slipped out of the bottle and onto the tire, it attracted grit and sand from the road. With all those particles sticking onto the tire, the tire was now a very good abrasive. As I pedaled, oblivious to the fact that the bottle was touching the tire, the tire had become a very good machining tool and shaved away a portion of the bottle, enough to get a clearance for the tire to pass unobstructed. Finally, when I stopped to check the water bottle at the park, all the juice was gone. The grit was stuck onto the tire.

Big things happen from a combination of little things, a train of events. It is interesting to be a casual inspector and study the hows behind these events. In this case, my haphazard use of a water bottle cage cost me a nice water bottle. Now to find out how I lost that screw......


Do you have any stories to share? Write to me here.

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15 'Decommisioned' Bicycles & Their Waste Stream

Keeping in with our theme of spills, crashes, injuries and utter turmoil, it has always struck me as to what people do with their destroyed carbon fiber bikes after a crash. Do they trash it in the dumpster? Do they try their best and send it somewhere for a repair? Do they salvage some parts and try to use them in a different application and setting? What would you do?

This blog has shown you a number of instances in the past where bikes and bicycle components have failed. Now often there is a legitimate reason for these occurrences which I don't want to go into. But what happens afterward? What do you do with this pile of seemingly junk metal and carbon fiber?

Recently, a reader and fan of this blog - Anthony Hendrickson, with Materials & Process Engineering at Boeing Rotorcraft Systems, sent me a photo of his friend's high end Pinarello. This rider went into a turn about three wide at speed and got pushed to the outside. He wound up going into a ditch/gully running parallel to the road and the bike just broke into two pieces. Take a look :


If something like this happened to a professional bike rider, he would of course get replaced immediately with a new one. The rest of us in the world may not always have this luxury. But as bike riders, we don't want to sit without a bike for long. Eventually, the money will come and we all will get a new bike, somehow. What happens to the old one?

If it is indeed decided that it should be disposed of, is there any possibility for carbon fiber to be recycled? This is an interesting subject because it turns out it isn't so easy to do this. I have captured two different thought processes when it comes to carbon fiber as a "clean" and recyclable material for the environment. I think they will interest you because most of us call ourselves 'clean' to the environment and fans of sustainable sports and transportation. But is that really true?

A. Repairing, Reusing And Recycling Disadvantages : "Carbon fiber falls short for three strategies in the field of waste reduction - Repair, Reuse, Recycle. Repairing a carbon fiber frame often requires more expertise and time than the frame is actually worth; if it can be repaired at all. Reusing carbon fiber tubes similarly requires the same advanced skills and technology to use them for some other function. Recycling it into its component parts may be feasible in the future, but the environmental and energy ramifications of that are unknown. Carbon fiber is one of those “monstrous hybrids” the Cradle to Cradle authors deplore. When you combine organic elements with inorganic elements you often create materials that don’t break down and can cause serious problems to living systems. Carbon fiber isn’t nearly as bad as say, dioxin, but it’s still a hybrid, and the authors argue that organic nutrients and “technological nutrients” need to be kept separate." - Admin, Bicycling Is Better

Now here's an opposite viewpoint, shedding a more positive light on carbon fiber's prospects for recycling.

B. Thermal Decomposition Possibilities : "When it is time to decommission CFRPs they cannot be melted down in air like many metals. When free of vinyl (PVC or polyvinyl chloride) and other halogenated polymers, CFRPs can be thermally decomposed via thermal depolymerization in an oxygen free environment. This can be accomplished in a refinery in a one-step process. Capture and reuse of the carbon and monomers is then possible. CFRPs can also be milled or shredded at low temperature to reclaim the carbon fiber, however this process shortens the fibers dramatically. Just as with downcycled paper, the shortened fibers cause the recycled material to be weaker than the original material. There are still many industrial applications that do not need the strength of full-length carbon fiber reinforcement. For example, chopped reclaimed carbon fiber can be used in consumer electronics, such as laptops. It provides excellent reinforcement of the polymers used even if it lacks the strength-to-weight ratio of an aerospace component." - Wikipedia entry on CFRP's.


In light of these two statements, do you think there's a distinct possibility that carbon fiber from our trashed bicycles could be recycled and reused, or is the technology still catching up with us? Is the bicycle industry studying solutions to make this happen, or do they really want to take opportunity of this 'repair and reuse' handicap? That would mean more sales for them in terms of new bikes and equipment, so why should they bother, eh?

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28 Campagnolo 11 Speed Chain Failure

Now if you don't use the Campy recommended, "200 dollar" chain tool to hook up your 11 speed chain, it will break. If not now, at some point. Because of the smaller tolerances and a special peening procedure involved, your conventional tool will not be able to seat the union bushing into the links properly. It will bend out and take the paper thin link along with it.

Only the mighty Campy tool can properly do the following while crapping in your wallet :

a) Support the left end of the link by clamping it while pushing the union bushing in adequately with a conical pusher.

b) Split the protruding end by a special hole provided in the tool.

c) Lock the bushing in the link ("locking the link"). 

Trust me, this is the Cadillac of chain tools. Your grandpa's tool just won't cut it.

Now I myself thought I could somehow get away without 'following the rules'. Oh no. Didn't work.

The following chain failure happened to me while climbing a long hill. I asked my local bike shop to equip themselves with the right tool and had them fix me a new chain. (I think its the right thing to do for them as now, it is likely that customers increasingly show up at their place with a 11 speed job)

Hey, just check out the width of this chain. This is technology right here.

Now start being amazed and see how a 11 speed chain is installed :