It's a design failure, don't beat about the bush, can be solved by- 1. Don't press down too hard on the pedal 2. Just leave the bike hanging in the shed 3. Take the chain off before you go out, this saves on constantly cleaning and lubing it 4. Live on a very high hill with a good neighbor who has a bike rack on their vehicle 5. Use the offside leg only, you'll only get half as tired 😫 6. Ride at night without lights, problems solved 👌
Having worked in cycle industry for almost 30 years. You're theory of regions is spot-on! I was in middle east and Asia for many years and saw a huge percentage of average cyclists with broken ultegra and dura ace chainsets than the UK. Keep up the good work
A couple of thoughts. The adhesive won't "corrode" from trapped moisture. Its an inert substance and simply wont react with any trapped water vapour Any galvanic corrosion between the axle and crank would cause the axle to corrode, not the Al I think the probable failure mechanism is due to your "meniscus effect" (actually capillary action where the surface tension of the liquid pulls the liquid into the gap) Aluminium doesn't "rust" as such in that the oxidation layer is not permeable so it is self healing. Oxygen is very much required for the substrate to form Aluminium oxide. I think what is happening is that the areas of failure are areas of high stress so the aluminium oxide is de-laminating (the substrate is more ductile that the oxide that protects it) allowing the substrate to further corrode as moisture is pulled into the gap and the lack of oxygen prevent further formation of the aluminium oxide layer. This leads to a repetitive corrosion event in a localised location that then leads to failure as the substrate is constantly eaten away with each cycle If trapped moisture within the crank was the culprit, a simple hole drill into the back to allow escape of the air with each thermal cycle would cure the issue
I have owned 2 of the effected cranks. A Dura-ace 9000 and a Ultegra 6800. BOTH have failed! That is a 100% failure rate. The first in 2017, which Shimano did nothing about. I bought a replacement for the Dura-ace 9000 left crank arm that failed. So when the 6800 started separating, I replaced it before it broke, so it didn't kill me. I never reported it to Shimano because I knew they would do nothing about it. Now that the recall is official, the number of reported failures is going to soar! Far beyond the 4519 they say they are aware of. But I think they have waited to issue the recall for over 4 years, when they knew there was a big problem, because a lot of those affected cranks have already failed, been thrown in the trash, and replaced already. And now, no longer available for inspection. So Shimano is off the hook. Very sleezy in my opinion.
Over the last 25 years, I've broken 4 Dura Ace cranks. 3 of the 4 have been right in the middle of the threaded pedal hole, going outward to the edges, then abruptly breaking off. I'm always careful not to over torque. Just a bit of pressure at the end to snug up the pedals on the cranks. These breaks have occurred both on the left and right crank arms. One break occurred in the middle of the drive side crank arm, about half way from the pedal to the spider. In all instances, I went down, once breaking a finger. Shimano was always good about replacing the crank sets. I examine mine but can never any cranks. It just happens all of a sudden. I'm 175 lbs. I do ride in very hilly area's in Northern California typically climbing at least 2k feet per ride, always dry weather riding. Back in the day when I was riding a 150 miles a week, Shimano advised me to replace my cranks every 3 years. Doesn't seem like this should be happening but it does. I don't abuse them, just use them. they are definitely a safety hazard. for me anyway. good luck with yours.
Great heads up and appreciate your time spent presenting this. As someone running Ultegra 6800 Crankset you’ve made me get my jewellers loop out to inspect the bonding. Like your stuff 👏🏻👏🏻
Interesting theory regarding high humidity and failure rates. It definitely makes sense. I have not had or heard of this issue locally, but I also live in a non-tropical climate.
Thanks for your very interesting video. Even if the details of your analysis are not spot on, I appreciate you focusing on this subject and bringing it to our/my attention.
There might also be another mechanism at play: stress corrosion cracking. Rock climbing expansion bolts by the sea in Thailand suffered from this such that they’ve moved to glue in Ti bolts
I'm in Cornwall in the UK I live by the coast I think it's moisture ingress but also the salt that comes with that moisture mine failed not long after riding through winter.
To combat the said Meniscus effect, fill the gap with grease. I apply grease/oil to all the metal to metal contact areas on my bike and it helped tremendously in terms of eliminating creaking, corrosion and seizing. Places includes: - All bolts that do not require loctite, including the minute gap between the bolt head and its immediate surrounding areas. - Stem/handlebar interface. - Stem/steertube interface. - Headset bearings/headtube interface. - QR/dropouts. - Chainring/crank interface. - Cassette/freehub interface. - Cable end cap/boss interface. - Wax on pedal/cleat interface. - Light oil on derailleur and brake caliper pivots. ...and more. Tedious jobs but effective.
Don't grease the stem-steerer and stem-handlebar interface, at least not with grease. If applicable, assembly grease could be used, but otherwise these surfaces should be clean and dry in order to provide the proper friction to not move under load. Grease dup you'll have to clamp them to idiot levels, which will just break stuff.
@@Primoz.r Thanks. I've been doing it for years and remains problem-free. However it does remind me of potential slippage. My rationale of greasing the interfaces is two-fold: 1. eliminate any chance of creaking and 2. more importantly keeps water and salt (from sweat) out. Obviously you do not want the stem/handlebar joint corroded by sweat.
@@Primoz.r I agree, greasing is not way to go in this case. You should increase friction, not reduce it. In my experience there is no way to get enough clamping force through maximum allowed torque when grease is used. But I found out that assembly paste is also problematic because its particles can cause abrasion of the steerer tube. There must be something better to use. Ideally that stuff would increase friction or even bond surfaces, it would insulate and seal while still allow disassembly. But certainly it should be without abrasive particles. For now I am ok with untreated steerer tube so I don't need to tighten headset regularly when I ride on extremely bumpy surfaces. But sweat in the steerer tube - aluminum interface can cause problems, so it is not perfect...
I'm late to the party, but to stop galvanic corrosion, use a paste such as duralac. Used in aviation and nautical industry to prevent corrosion between different metals.
11:34 'Degassing' In automotive industry, it's called Pressure Neutralization Ventilating Port, allowing air to move in and out, but restrictive to moisture. Apparently Shimano is not ready to implement this.
Many years as a shop mechanic in Australia and zero failures through the shop, zero. Worked also with maybe pro teams and only one arm failure with Dockers left crank. Obviously this is happening, but I would be interested in a quick division, about sold divided by the amount failed. Pretty confident the answer will be tiny. Great video and I think you've nailed the reasons. But once again, zero through our store and never even heard of any other stores having issues. Many as we have little humidity
@@randomdude5938 fair call, I have to admit I'm properly wrong. May have a lot to do where I live and the failure rate was obviously less, maybe. Either way Shimano has lost me as a fan, not so much for the issue, but they way they handled it over the past and now
Hi. Mine failed exactly like this. 20k miles on it in the UK. It was on my winter bike so had lots of exposure to moisture and salt. Also stored outside in a very cold garage going through multiple cold temperature cycles. For reference it was 7 years old
Galvanic corrosion absolutely does happen between steel and aluminium but it does take a quite a while and usually needs help. It's a common issue in automotive repair for seized parts, a common one being steel wheel hub in an aluminum steering knuckle. 10 years with some added electrolytes in the way of road salt usually does the trick. In the absence of moisture and electrolyte there is usually little to no issue such as steel bolts into blind hole aluminum suspension/chassis parts.
My brother is 6'6" and I'm 6'3" and we can put down a lot of power at times. We both have only used Shimano until I bought a Cannondale with their crankset. We've never had an issue with Shimano cranks. We do live in N. Carolina though. I must admit that the issue had me a little worried.
The thermal cycling makes sense regarding the regions you mentioned. In Miami particularly you go from 100% humidity and super hot weather to super cold Air Conditioned houses/apts/etc...
Awesome vid, thanks. Had not heard of this issue anywhere else. Was also not aware of the fabrication methods of Shimano cranks. Not the first time in the manufacturing world that the assumption if airliners can be assembled with glue bonded aluminum that it will work in any other application :)
Good video like the approach to and analysis of the problem. Only solution: go Cannondale Hollowgram! Been riding them since I toured the old factory in PA and saw the manufacturing process firsthand with zero problems of ~11k miles
I live on the Gulf Coast of Central Florida. I have had 2 sets of Uletgra's crack on me. One set was the 6800's and the other was the 8000's. I now have a set of ROTOR cranks on my bike.
A friend of mine has just over 30,000 miles on his r9000 crankset and we're in the green zone. Still going strong. He doesn't ride it in the winter and tries to avoid rain.
Precisely where my Shimano DA-9000 crank’s three spiders started to show splitting (at the bonding interfaces) while unfastening the crank bolts. Had lost so much sleep thinking what could have been robbing me of the usual performance with same (and sometimes greater) efforts on same exact bike, route, times of day & night, energy/mood levels, hydration...etc ! Had a warranty issue raised with Shimano and received a brand new identical crankset replacement. Several months in amd same issue started to surface, and again received a brand new crankset replacement which I decided to sell off and got a ROTOR crankset replacement which actually worked fine. * This happened in tropical Singapore city where normal humidity could reach as high as 80~90% As of this evening (07th March 2021, 12:52am) humidity is at 82%.
This is a great vid, with the potential root causes. 👍 I believe, whether will it grant shimano or any company a recall, is not by product failure, but by severity of the failure’s impact onto the user and it’s surroundings, such example is, if the failure is catastrophically causing bodily harm. Regardless, this is certainly doing shimano quite a damage isn’t?
I suspect that the shear forces that act on the cranks also play a part in weakening the bonding agent used and lead to slow mechanical breakdown of the adhesive. In places where there's a lot of heat and high humidity the deterioration of such compromised cranks will be significantly faster than in in places with a fairly dry and/or colder climate.
I’m north west UK and have had a 6800 ultegra rh crank fail, shimano didn’t warranty it either meaning I had to replace with an R8000. Also got 2 club mates who’ve suffered the same on 6800. I should also add that my failure started with a creak under load, a twisting moment could be seen when looking down as torque was applied which ran along the length of the bonding from the spider end towards the pedal. This suggests to me the torsional movement between the 2 sections fatigues the bonding to allow moisture in and as time progresses the split in the bonding propagates along the arm. I had no signs of corrosion in the areas where the chain rings but against the arm. The crankset that failed for me was well used (approx 15000 miles) but was well maintained and cleaned inc using compressed air to blow off water before towel drying and storing within the main house.
@Peak Torque You mentioned vacuum sealed construction prior to final enclosure, but why not leave a tiny hole to be vacuum sealed after. I'd assume holes at this level are sacrilege, although vacuum sealed holes could be hidden on the inside of another face, like the next insert. And if vacuum is too shit (for production 2020), leaving hygroscopic material (how lightweight is nylon?) on the rest of the bare interior surfaces seems stupid easy. A quarter ounce is what I'd use
Very interesting finding and analysis. How is the inner mainland and coastal areas making the difference? I would assume the humidity is one factor while the salt in the air at coastal area might be another contributor?
Living in Auckland, obviously, by the see with high humidity, I've never seen nor heard of these failures before. Our summer temps reach above 30 degrees, and rarely go below 8 at night in the Winter. So maybe it is just that equatorial band that has problems.
Um, I say bullshit. Maybe, just maybe the original Record Carbon cranks (de-lamination of the pedal interface). Certainly not since going to the Hirth since leaving the square taper. On the same context I could claim to have "broken" no less than 15 or so Specialized Allex Epic Pro Carbon framesets....never mind they were pre-production and Giant/Martec had yet to figure out the proper glue....
@@systemsbroken The all steel alloy, regular production Campy Nuovo Record crank arms and bottom bracket I broke in the 1980's all apparently developed micro cracks in them, unbeknownst to me, and all did indeed break while I was riding. One crank arm broke while I was accelerating out of a corner in a criterium in Gainesville FL. Thankfully I didn't crash, and I rode one-legged back to the S/F line, the broken piece of crank arm and that pedal dangling from my shoe. Another crank arm broke as I stood up to accelerate after a traffic light turned green in the town where I live. Because I was going so slow, I simply fell over in the street. The bottom bracket spindle I broke was on a training ride with several other riders. We were just starting a "green sign" sprint on a rural country road when again I stood up to accelerate and the spindle snapped, sending me to the pavement, taking another rider down with me, and a trip to the ER for me to get several stitches for a cut in my scalp. I was wearing a leather hairnet type helmet, and figured possibly the other guy's front wheel skewer went in between the straps and cut me. No bullshit.
@@systemsbroken No, I live between Ocala and Orlando, and after I quit racing in 2008 I haven't ridden more than 20 miles from my house, and in fact for many months now I have been riding exclusively on my rollers due to a crack in the seat tube of my aluminum frame bike (2001 Schwinn Fastback Factory), just above the bottom bracket weld. Yeah, something else I have broken, and I was not even a sprinter! Figure it is safe enough on rollers, but too dangerous for the road, and not a priority in my life to get a new frame/bike.
Thanks for the in depth analysis. I would like to throw a much simpler reason into the equation - Sweat. I’ve been a professional mechanic for over 20 years in Australia (the tropic part) and I’ve seen the results of sweat eating just about anything on a bike, even down to aluminium bars snapping due to the corrosion of sweat. I have seen plenty of these shimano failures, one saving grace might be that shimano does have a decent warranty period. Hopefully they’ll get to a solution. Thanks again for the video.
Is there any public information about what process/design changes were made for the 12-speed Ultegra and DuraAce cranks (which are not part of the recall and are being used as replacements)? If not, I would love to see a tear-down and analysis before trusting them.
Good vid. If humidity is the issue, it would be simple to assemble them in an Argon atmosphere. The main benefit is no design or material changes are needed. Oh yeah, and not breaking.
XTR M9000 appears to be bonded in just two pieces, where the back is a relative plane, and everything else is what it acts as a lid on when put together. I have some that have seen the struggle and keep getting used hard.
Just failed my second R8000 crankset. New bike purchased at the end of 2018. First cranks broke on both sides an inch or so above the pedal hole. Shimano replaced for free. Second set just broke but this time only on the drive side but in the same place. I can confirm that I have white powdery substance between the crank spider and the chainrings and I agree that I think that corrosion is the entry point for the failure to happen. Waiting to see if Shimano replaces it again. If they do I may either start vacuuming out the gap or spraying WD-40 in there regularly. I do not think there is a solution, I will continue to break them on a nearly yearly basis. I do suffer from hyperhidrosis and live in Alabama so I’m just north of the band shown in the video. Will likely move down to non-bonded 105 if they do not replace.
I lived on Windward (the very wet side) Oahu for 11 years, I can affirm that tropics utterly brutal and unforgiving on everything. I remember sometime in rain storm we'd have 90 + percent humidity inside the house. Leather turn white with mil-drew, plastics get brittle, exposed steel rusts within hours and green algae can grow indoors. We sealed off one room and ran a dehumidifier and AC to protect paper good like old LPs, scarp book, collectables etc, even sealed I'd empty out 3 gallons of water at least once a day. In terms of bikes stuff I've seen tons of clear coated carbon go yellow in two seasons. The biggest thing more than the humidity was the UV. I had Oakley photochromic lenses that would be jet black by 9 am. Oakley original listed them down to 11 percent transparency but in other parts of world like California they wouldn't get very dark and Oakley relisted them to 23%. Hawai'i also had a day where sun directly overhead and no shadow is cast. Everyone thinks Hawai'i is paradise.. czcams.com/video/dh_eZ40e9Po/video.html da.. reality like talk story bout dakine... czcams.com/video/Iz3rubGrGZQ/video.html&
Hello 👋 Sofian form CB Bike Store base in Brunei Darussalam. I had the same issue with my Ultegra R8000 crankset. I ride regularly. My bike is less than 2 years old. I wash my bike at least once a week. So it could be corrosion building up. Good video 👍 bro.
I think that I have heard of an effect where surface tension (your meniscus) effect adds surface energy and increases corrosion. However, literally seconds of Google research brought up several articles on "crevice corrosion" but suggested that aluminium is not particularly susceptible. If that gap was a typical stress raiser then that would have been found pre-production. But is there a chance that crevice corrision is sharpening the gap to increase the stress intensity? It does seem that the cracks are starting where the constraint is high.
I had an Ultegra 6800 crank fail and I replaced it with an 8000. The 6800 has holes in the rear of the spider but the 8000 does not, so I surmised that it was due to moisture and salt ingress. A friend of mine also had one fail just a couple of weeks ago
It's just happened to me in tropical Kendal. Coming down Kentmere at speed, crank snapped just above where the pedal attaches. Lucky not to have a bad crash, just kept the bike upright...
I had a failure of a Dura Ace 9000 crankset... but the steel axle!!! No failures on cranks at all. I stripped the axle on the left, approximately where it is inserted into the left bearing.
This brings up bad memories of a 90's era Super Record Crankset failure that resulted in a broken collar bone. It happened on the last of a series of sprint intervals at high fairly high speed.
I have broken 3 Ultegras - two at the spider and one the back panel (inside side of the crank). I live the northeast United States, but I do sweat a lot. All failures happened in < 15 months. I upgraded to Dura Ace, but sounds like they are just as bad, albeit with a 3 year warranty.
Because each successful product starts as a solid reliable product. Only yearly margin improvement targets make things like "Planned Obsolescence" or "Manufacturing optimizations to save materials and cost" to come into the picture, at a later point ..
I have seen two Ultegra failures both in South wales [to club mates], its pretty common here. luckily neither incidents I have witnessed resulted in injury but pretty scary. neither cranks were especially old
I live in cairns Australia, close to the equator. While I’ve never busted a crank personally I’ve seen two ultegra cranks that have failed here in town.
Even if you coat it with a substance to reduce the surface tension then you would also have to address capillary/wicking action depending on how small the gap is.
i snapped a crank set in the mid 1980s, first the drive side and exactly 1 year later, the non drive side . the cranks were italian, a company called Cambio Rino, then I switched to ultegra
I actually snapped my Shimano Hollowtech 105 crank axle about 2 years ago just before its bonded into the spider. I would add a photo if I could however I could send you one if you want to see it and explain how and where I did it in the UK.
Ive changed shimano to single plate doval and i cant sense any flex and the weight is 30 grams more on dura ace 9100. Also, aren't dura ace axle spindles alloy?
If it's sealed in water vapor, then colder climates would not be immune to the problem and would probably accentuate it. If meniscus effect then maybe that would correspond more to wetter climates (so tropical), but then why is it also not more frequent in notoriously wet northern countries (like the UK)? Nice video though. Appreciate the thoughtful analysis
great video, I will probably not have to worry about this problem but in the future I'll try to store my bike in my apartment and not the garage and use GT85
You talked about the garage storage, I think in Asia lots of people also storing their bike on their balcony. Cold AF in winter and then hot as balls in the summer sun.
Good point Joe. Asian balconies EAT aluminium. Especially bars. I only put mine outdoors when im particularly pissed off with it...my nrw TCR lives in a de-humidified room 😉
Regarding heat and humidity, spending 2~3 weeks in the ocean, enclose in ocean containers certainly won’t help. If they spray the cavity with foam, maybe that will minimize air volume while keep the weight down.
I've had two ultegra 6800 right crank arm failures on my cx bike, in about 7000 miles, the second cranked failing within 2years and about 2000 miles max. This is Scotland. I know at least a dozen of my 100 followers on strava that live within about 20 miles that have all had at least one failure as as well ... almost all were 6800, although there were a couple of durable ace as well. I've switched to 5800 as its a solid crank I believe.
I’ve seen three crank failures local to me in Scotland. All 6800 Ultegra models, two of them from the club I’m in, and another when I passed another cyclist who was walking along the road after his cranks failing.
Yikes, I live in that tropical zone. In a super high moisture area and that combined with dirty roads and fine sandy dirt on them is really tough on parts, especially bottom brackets. as for the cranksetm I have 105, whew
My DA9000 split apart a couple of years ago, started off with clicking on each peddle stroke the whilst investigating it literally fell in two, it had done dry miles only and looked in tip top condition, I live in England.
I've worked in bike shops for the last 23 years. The bonded Hollowtech 2 arms mostly 6800 and 9000 series, fail. I've seen mostly rights. About twenty, give or take. Corrosion related, every one, but still shouldn't be happening. All had corrosion around the spider/chaining interface and all had rusty stem bolts, rusted front derailleur parts, very smelly bar tape. Mid-Atlantic, DC area, if it makes a difference.
@@n0ch91c3s im based in london. If the bikes are in that condition it cant really be deemed as a manufacturing fault. Light weight race compents need to be cleaned and maintained or they will fail
@@gclh22 I totally understand. It's one big reason why I'm on the fence about how I feel about it. On the one hand, it's definitely from some level of neglect. On the other hand, this is SHIMANO. They hold themselves to a higher standard and so do we. It happens to Dura Ace, the Ace of Durability. Also it only happens to their bonded arms. Although I have seen the occasional fracture of their previous welded Dura Ace and XTR, it was much much more rare and not from corrosion. Also the failure mode was gradual, not catastrophic.
The old Dura Ace 7703 cranksets have 3mm thick sidewalls and were laser welded together. An engineer at Speciality Race Products told me, that the fatigue resistance of XTR crank, of that generation, was well beyond was necessary. And what did we see about 20 years later, much lighter cranks. You would be better served by a map of ambient humidity. If humidity is the problem, then anywhere along the sea coast would be a problem. I know people who go out in ride in -8C, would that cycles of temperature extremes not cause more problems than tropical climates? Could be simpler, on very humid days there could possibly be a bonding problem.
Very interesting. 🤔 condensation is inevitable. Especially in coastal towns high salt content in the atmosphere. Untreated surfaces will oxidize. Leaving your Air conditioned apartment for a ride on the board walk on a humid day can accelerate the process.
There's a point where decreasing weight starts to compromise strength and longevity for the current state of technology. So nothing to complain about in my opinion. Just sacrifice the few grams and get a solid crank.
One thing about the failures in that instagram account is that people with broken parts tend to post their experiences online, so of course that instagram account, where the failure cases are concentrated, makes Shimano's failure rate look "a lot". Those with long-lasting Shimano cranks like me or you would just go on with our rides and thus not being vocal about it. As the other comment said, a quantification of the failure rate is needed and then we can see whether it is acceptable or not.
Just wondering why we're not seeing the same issues with Cannondale SiSl cranks, don't they use a similar clam shell construction? I know the chainring construction is different but the cranks are similarly constructed?
Hydrophobic paint? GE silicone compound + mineral spirit, to a consistency suitable for spray nozzle. Only good for fresh crank out of the box. Hydrophobic reliability issue if apply after mileage built up or ran on wet road. The most difficult part is availability on radial spray nozzle mounted on a straw.
If they transferred manufacturing somewhere else then there may be some shortcuts in the manufacturing process. It would be good to know from which manufacturing site these products came from. Excellent manufacturing companies are able to trace this back through product codes. The best manufacturers know on what day, shift, and production line the defective product was made. Then again, it could also be a marketing tactic of a rival brand or another brand that would like to enter into the category.
This video was posted THREE YEARS AGO and Shimano is just now recalling cranksets?!?! Unbelievable!
I just assumed I was putting out far too much power for any metal construction to withstand.
That would be the most plausible explanation. ;-)
It's a design failure, don't beat about the bush, can be solved by-
1. Don't press down too hard on the pedal
2. Just leave the bike hanging in the shed
3. Take the chain off before you go out, this saves on constantly cleaning and lubing it
4. Live on a very high hill with a good neighbor who has a bike rack on their vehicle
5. Use the offside leg only, you'll only get half as tired 😫
6. Ride at night without lights, problems solved 👌
Having worked in cycle industry for almost 30 years. You're theory of regions is spot-on! I was in middle east and Asia for many years and saw a huge percentage of average cyclists with broken ultegra and dura ace chainsets than the UK. Keep up the good work
Really love the engineering insight on cycling you give bud! Keep it up!!
A couple of thoughts.
The adhesive won't "corrode" from trapped moisture. Its an inert substance and simply wont react with any trapped water vapour
Any galvanic corrosion between the axle and crank would cause the axle to corrode, not the Al
I think the probable failure mechanism is due to your "meniscus effect" (actually capillary action where the surface tension of the liquid pulls the liquid into the gap)
Aluminium doesn't "rust" as such in that the oxidation layer is not permeable so it is self healing. Oxygen is very much required for the substrate to form Aluminium oxide.
I think what is happening is that the areas of failure are areas of high stress so the aluminium oxide is de-laminating (the substrate is more ductile that the oxide that protects it) allowing the substrate to further corrode as moisture is pulled into the gap and the lack of oxygen prevent further formation of the aluminium oxide layer.
This leads to a repetitive corrosion event in a localised location that then leads to failure as the substrate is constantly eaten away with each cycle
If trapped moisture within the crank was the culprit, a simple hole drill into the back to allow escape of the air with each thermal cycle would cure the issue
I have owned 2 of the effected cranks. A Dura-ace 9000 and a Ultegra 6800. BOTH have failed! That is a 100% failure rate. The first in 2017, which Shimano did nothing about. I bought a replacement for the Dura-ace 9000 left crank arm that failed. So when the 6800 started separating, I replaced it before it broke, so it didn't kill me. I never reported it to Shimano because I knew they would do nothing about it. Now that the recall is official, the number of reported failures is going to soar! Far beyond the 4519 they say they are aware of. But I think they have waited to issue the recall for over 4 years, when they knew there was a big problem, because a lot of those affected cranks have already failed, been thrown in the trash, and replaced already. And now, no longer available for inspection. So Shimano is off the hook. Very sleezy in my opinion.
Over the last 25 years, I've broken 4 Dura Ace cranks. 3 of the 4 have been right in the middle of the threaded pedal hole, going outward to the edges, then abruptly breaking off. I'm always careful not to over torque. Just a bit of pressure at the end to snug up the pedals on the cranks. These breaks have occurred both on the left and right crank arms. One break occurred in the middle of the drive side crank arm, about half way from the pedal to the spider. In all instances, I went down, once breaking a finger. Shimano was always good about replacing the crank sets. I examine mine but can never any cranks. It just happens all of a sudden. I'm 175 lbs. I do ride in very hilly area's in Northern California typically climbing at least 2k feet per ride, always dry weather riding. Back in the day when I was riding a 150 miles a week, Shimano advised me to replace my cranks every 3 years. Doesn't seem like this should be happening but it does. I don't abuse them, just use them. they are definitely a safety hazard. for me anyway. good luck with yours.
Great heads up and appreciate your time spent presenting this. As someone running Ultegra 6800 Crankset you’ve made me get my jewellers loop out to inspect the bonding.
Like your stuff 👏🏻👏🏻
Loupe ffs!
Interesting theory regarding high humidity and failure rates. It definitely makes sense. I have not had or heard of this issue locally, but I also live in a non-tropical climate.
Thanks for your very interesting video. Even if the details of your analysis are not spot on, I appreciate you focusing on this subject and bringing it to our/my attention.
There might also be another mechanism at play: stress corrosion cracking. Rock climbing expansion bolts by the sea in Thailand suffered from this such that they’ve moved to glue in Ti bolts
I'm in Cornwall in the UK I live by the coast I think it's moisture ingress but also the salt that comes with that moisture mine failed not long after riding through winter.
To combat the said Meniscus effect, fill the gap with grease. I apply grease/oil to all the metal to metal contact areas on my bike and it helped tremendously in terms of eliminating creaking, corrosion and seizing. Places includes:
- All bolts that do not require loctite, including the minute gap between the bolt head and its immediate surrounding areas.
- Stem/handlebar interface.
- Stem/steertube interface.
- Headset bearings/headtube interface.
- QR/dropouts.
- Chainring/crank interface.
- Cassette/freehub interface.
- Cable end cap/boss interface.
- Wax on pedal/cleat interface.
- Light oil on derailleur and brake caliper pivots.
...and more.
Tedious jobs but effective.
Great tip that
Don't grease the stem-steerer and stem-handlebar interface, at least not with grease. If applicable, assembly grease could be used, but otherwise these surfaces should be clean and dry in order to provide the proper friction to not move under load. Grease dup you'll have to clamp them to idiot levels, which will just break stuff.
@@Primoz.r Thanks. I've been doing it for years and remains problem-free. However it does remind me of potential slippage. My rationale of greasing the interfaces is two-fold: 1. eliminate any chance of creaking and 2. more importantly keeps water and salt (from sweat) out. Obviously you do not want the stem/handlebar joint corroded by sweat.
@@Primoz.r I agree, greasing is not way to go in this case. You should increase friction, not reduce it. In my experience there is no way to get enough clamping force through maximum allowed torque when grease is used. But I found out that assembly paste is also problematic because its particles can cause abrasion of the steerer tube. There must be something better to use. Ideally that stuff would increase friction or even bond surfaces, it would insulate and seal while still allow disassembly. But certainly it should be without abrasive particles.
For now I am ok with untreated steerer tube so I don't need to tighten headset regularly when I ride on extremely bumpy surfaces. But sweat in the steerer tube - aluminum interface can cause problems, so it is not perfect...
I'm late to the party, but to stop galvanic corrosion, use a paste such as duralac. Used in aviation and nautical industry to prevent corrosion between different metals.
A friend of mine has broken 2 Ultegra crank sets through no fault of his own. His was the crank arm and lives in North Carolina USA.
Alabama rider- My 9100 series Dura Ace drive side crank arm after 18 months of riding. Enjoyed the presentation.
A brilliant informatech to the manufacturers and users. thanks!
11:34 'Degassing'
In automotive industry, it's called Pressure Neutralization Ventilating Port, allowing air to move in and out, but restrictive to moisture.
Apparently Shimano is not ready to implement this.
Many years as a shop mechanic in Australia and zero failures through the shop, zero. Worked also with maybe pro teams and only one arm failure with Dockers left crank. Obviously this is happening, but I would be interested in a quick division, about sold divided by the amount failed. Pretty confident the answer will be tiny. Great video and I think you've nailed the reasons. But once again, zero through our store and never even heard of any other stores having issues. Many as we have little humidity
Lol this aged like milk. Tell me more expert mechanic.
@@randomdude5938 fair call, I have to admit I'm properly wrong. May have a lot to do where I live and the failure rate was obviously less, maybe. Either way Shimano has lost me as a fan, not so much for the issue, but they way they handled it over the past and now
Great great video. 👌🏾. Jim. Colnago V3Rs owner and Air Traffic Controler
Two of my friends have had failure on 6800 here in Oslo. Those bikes have been ridden during winter exposed to lots of snow and salt.
Hi. Mine failed exactly like this. 20k miles on it in the UK. It was on my winter bike so had lots of exposure to moisture and salt. Also stored outside in a very cold garage going through multiple cold temperature cycles. For reference it was 7 years old
And are you fine with it? Did you crash or anything that would have hurt you? This is mind blowing
Galvanic corrosion absolutely does happen between steel and aluminium but it does take a quite a while and usually needs help. It's a common issue in automotive repair for seized parts, a common one being steel wheel hub in an aluminum steering knuckle. 10 years with some added electrolytes in the way of road salt usually does the trick. In the absence of moisture and electrolyte there is usually little to no issue such as steel bolts into blind hole aluminum suspension/chassis parts.
My brother is 6'6" and I'm 6'3" and we can put down a lot of power at times. We both have only used Shimano until I bought a Cannondale with their crankset. We've never had an issue with Shimano cranks. We do live in N. Carolina though. I must admit that the issue had me a little worried.
I live in UK, had this problem with 6800 ultegra, 2000miles. Happy with sram red
The thermal cycling makes sense regarding the regions you mentioned. In Miami particularly you go from 100% humidity and super hot weather to super cold Air Conditioned houses/apts/etc...
Love the timing of the Algorithm 😂
Awesome vid, thanks. Had not heard of this issue anywhere else. Was also not aware of the fabrication methods of Shimano cranks. Not the first time in the manufacturing world that the assumption if airliners can be assembled with glue bonded aluminum that it will work in any other application :)
Good video like the approach to and analysis of the problem. Only solution: go Cannondale Hollowgram! Been riding them since I toured the old factory in PA and saw the manufacturing process firsthand with zero problems of ~11k miles
I live on the Gulf Coast of Central Florida. I have had 2 sets of Uletgra's crack on me. One set was the 6800's and the other was the 8000's. I now have a set of ROTOR cranks on my bike.
A friend of mine has just over 30,000 miles on his r9000 crankset and we're in the green zone. Still going strong. He doesn't ride it in the winter and tries to avoid rain.
Precisely where my Shimano DA-9000 crank’s three spiders started to show splitting (at the bonding interfaces) while unfastening the crank bolts.
Had lost so much sleep thinking what could have been robbing me of the usual performance with same (and sometimes greater) efforts on same exact bike, route, times of day & night, energy/mood levels, hydration...etc !
Had a warranty issue raised with Shimano and received a brand new identical crankset replacement.
Several months in amd same issue started to surface, and again received a brand new crankset replacement which I decided to sell off and got a ROTOR crankset replacement which actually worked fine.
* This happened in tropical Singapore city where normal humidity could reach as high as 80~90%
As of this evening (07th March 2021, 12:52am) humidity is at 82%.
This is a great vid, with the potential root causes. 👍
I believe, whether will it grant shimano or any company a recall, is not by product failure, but by severity of the failure’s impact onto the user and it’s surroundings, such example is, if the failure is catastrophically causing bodily harm.
Regardless, this is certainly doing shimano quite a damage isn’t?
very insightful. Thanks!!!
I suspect that the shear forces that act on the cranks also play a part in weakening the bonding agent used and lead to slow mechanical breakdown of the adhesive. In places where there's a lot of heat and high humidity the deterioration of such compromised cranks will be significantly faster than in in places with a fairly dry and/or colder climate.
I’m north west UK and have had a 6800 ultegra rh crank fail, shimano didn’t warranty it either meaning I had to replace with an R8000. Also got 2 club mates who’ve suffered the same on 6800. I should also add that my failure started with a creak under load, a twisting moment could be seen when looking down as torque was applied which ran along the length of the bonding from the spider end towards the pedal. This suggests to me the torsional movement between the 2 sections fatigues the bonding to allow moisture in and as time progresses the split in the bonding propagates along the arm. I had no signs of corrosion in the areas where the chain rings but against the arm.
The crankset that failed for me was well used (approx 15000 miles) but was well maintained and cleaned inc using compressed air to blow off water before towel drying and storing within the main house.
@Peak Torque
You mentioned vacuum sealed construction prior to final enclosure, but why not leave a tiny hole to be vacuum sealed after. I'd assume holes at this level are sacrilege, although vacuum sealed holes could be hidden on the inside of another face, like the next insert. And if vacuum is too shit (for production 2020), leaving hygroscopic material (how lightweight is nylon?) on the rest of the bare interior surfaces seems stupid easy. A quarter ounce is what I'd use
Very interesting finding and analysis. How is the inner mainland and coastal areas making the difference? I would assume the humidity is one factor while the salt in the air at coastal area might be another contributor?
The algorithm will be loving this video lol
Living in Auckland, obviously, by the see with high humidity, I've never seen nor heard of these failures before. Our summer temps reach above 30 degrees, and rarely go below 8 at night in the Winter. So maybe it is just that equatorial band that has problems.
Perhaps capillary action would describe what you mean by the meniscus effect. Thanks for the video.
Reminds me of my younger days, back in the 1980's, when I broke 3 Campy Record crank arms, and also a Campy Record bottom bracket spindle.
+9000 watts
Um, I say bullshit. Maybe, just maybe the original Record Carbon cranks (de-lamination of the pedal interface). Certainly not since going to the Hirth since leaving the square taper. On the same context I could claim to have "broken" no less than 15 or so Specialized Allex Epic Pro Carbon framesets....never mind they were pre-production and Giant/Martec had yet to figure out the proper glue....
@@systemsbroken The all steel alloy, regular production Campy Nuovo Record crank arms and bottom bracket I broke in the 1980's all apparently developed micro cracks in them, unbeknownst to me, and all did indeed break while I was riding. One crank arm broke while I was accelerating out of a corner in a criterium in Gainesville FL. Thankfully I didn't crash, and I rode one-legged back to the S/F line, the broken piece of crank arm and that pedal dangling from my shoe. Another crank arm broke as I stood up to accelerate after a traffic light turned green in the town where I live. Because I was going so slow, I simply fell over in the street. The bottom bracket spindle I broke was on a training ride with several other riders. We were just starting a "green sign" sprint on a rural country road when again I stood up to accelerate and the spindle snapped, sending me to the pavement, taking another rider down with me, and a trip to the ER for me to get several stitches for a cut in my scalp. I was wearing a leather hairnet type helmet, and figured possibly the other guy's front wheel skewer went in between the straps and cut me. No bullshit.
@@lloydhlavac6807 Have i met you in the past year near Gainesville or Ocala?
@@systemsbroken No, I live between Ocala and Orlando, and after I quit racing in 2008 I haven't ridden more than 20 miles from my house, and in fact for many months now I have been riding exclusively on my rollers due to a crack in the seat tube of my aluminum frame bike (2001 Schwinn Fastback Factory), just above the bottom bracket weld. Yeah, something else I have broken, and I was not even a sprinter! Figure it is safe enough on rollers, but too dangerous for the road, and not a priority in my life to get a new frame/bike.
3 years later, a recall. Shimano has shit on us.
Thanks for the in depth analysis. I would like to throw a much simpler reason into the equation - Sweat.
I’ve been a professional mechanic for over 20 years in Australia (the tropic part) and I’ve seen the results of sweat eating just about anything on a bike, even down to aluminium bars snapping due to the corrosion of sweat.
I have seen plenty of these shimano failures, one saving grace might be that shimano does have a decent warranty period.
Hopefully they’ll get to a solution.
Thanks again for the video.
Is there any public information about what process/design changes were made for the 12-speed Ultegra and DuraAce cranks (which are not part of the recall and are being used as replacements)? If not, I would love to see a tear-down and analysis before trusting them.
Fantastic content again. Thank you!
Good vid. If humidity is the issue, it would be simple to assemble them in an Argon atmosphere. The main benefit is no design or material changes are needed. Oh yeah, and not breaking.
XTR M9000 appears to be bonded in just two pieces, where the back is a relative plane, and everything else is what it acts as a lid on when put together. I have some that have seen the struggle and keep getting used hard.
Fascinating video. What sort of engineering did you study? Aerospace? You inspire me to become an engineer.
Just failed my second R8000 crankset. New bike purchased at the end of 2018. First cranks broke on both sides an inch or so above the pedal hole. Shimano replaced for free. Second set just broke but this time only on the drive side but in the same place. I can confirm that I have white powdery substance between the crank spider and the chainrings and I agree that I think that corrosion is the entry point for the failure to happen. Waiting to see if Shimano replaces it again. If they do I may either start vacuuming out the gap or spraying WD-40 in there regularly. I do not think there is a solution, I will continue to break them on a nearly yearly basis. I do suffer from hyperhidrosis and live in Alabama so I’m just north of the band shown in the video. Will likely move down to non-bonded 105 if they do not replace.
I lived on Windward (the very wet side) Oahu for 11 years, I can affirm that tropics utterly brutal and unforgiving on everything. I remember sometime in rain storm we'd have 90 + percent humidity inside the house. Leather turn white with mil-drew, plastics get brittle, exposed steel rusts within hours and green algae can grow indoors. We sealed off one room and ran a dehumidifier and AC to protect paper good like old LPs, scarp book, collectables etc, even sealed I'd empty out 3 gallons of water at least once a day. In terms of bikes stuff I've seen tons of clear coated carbon go yellow in two seasons. The biggest thing more than the humidity was the UV. I had Oakley photochromic lenses that would be jet black by 9 am. Oakley original listed them down to 11 percent transparency but in other parts of world like California they wouldn't get very dark and Oakley relisted them to 23%. Hawai'i also had a day where sun directly overhead and no shadow is cast. Everyone thinks Hawai'i is paradise.. czcams.com/video/dh_eZ40e9Po/video.html da.. reality like talk story bout dakine... czcams.com/video/Iz3rubGrGZQ/video.html&
Hello 👋 Sofian form CB Bike Store base in Brunei Darussalam. I had the same issue with my Ultegra R8000 crankset. I ride regularly. My bike is less than 2 years old. I wash my bike at least once a week. So it could be corrosion building up. Good video 👍 bro.
Netherlands, and I had such a failure. (In about two years, crank side, the bike was stored indoors, milage: les then 30.000 km)
Interesting. I live in the hot-n-humid, but I've never heard of this issue. But I don't work at a bike shop.
I think that I have heard of an effect where surface tension (your meniscus) effect adds surface energy and increases corrosion.
However, literally seconds of Google research brought up several articles on "crevice corrosion" but suggested that aluminium is not particularly susceptible.
If that gap was a typical stress raiser then that would have been found pre-production. But is there a chance that crevice corrision is sharpening the gap to increase the stress intensity?
It does seem that the cracks are starting where the constraint is high.
Thanks for the warning since I own the Ultegra 6703 crankset.
6703 not affected.. they are forged not bonded.
I had an Ultegra 6800 crank fail and I replaced it with an 8000. The 6800 has holes in the rear of the spider but the 8000 does not, so I surmised that it was due to moisture and salt ingress. A friend of mine also had one fail just a couple of weeks ago
It's just happened to me in tropical Kendal. Coming down Kentmere at speed, crank snapped just above where the pedal attaches. Lucky not to have a bad crash, just kept the bike upright...
On the drive side, btw. Ultegra 6800. Gonna replace with 105, methinks.
In hope of inhibiting galvanic corrosion, I'm switching to dielectric (i.e. silicone) grease for less-demanding applications,. Any thoughts?
I had a failure of a Dura Ace 9000 crankset... but the steel axle!!! No failures on cranks at all. I stripped the axle on the left, approximately where it is inserted into the left bearing.
None in Northern Europe? I saw one fail in Aberdeen. Salty roads?
This brings up bad memories of a 90's era Super Record Crankset failure that resulted in a broken collar bone. It happened on the last of a series of sprint intervals at high fairly high speed.
I have broken 3 Ultegras - two at the spider and one the back panel (inside side of the crank). I live the northeast United States, but I do sweat a lot. All failures happened in < 15 months. I upgraded to Dura Ace, but sounds like they are just as bad, albeit with a 3 year warranty.
And here I am still riding on Dura-Ace square taper from the early 80s and the damn things won't break.
Because each successful product starts as a solid reliable product. Only yearly margin improvement targets make things like "Planned Obsolescence" or "Manufacturing optimizations to save materials and cost" to come into the picture, at a later point ..
I have seen two Ultegra failures both in South wales [to club mates], its pretty common here. luckily neither incidents I have witnessed resulted in injury but pretty scary. neither cranks were especially old
I live in cairns Australia, close to the equator. While I’ve never busted a crank personally I’ve seen two ultegra cranks that have failed here in town.
Even if you coat it with a substance to reduce the surface tension then you would also have to address capillary/wicking action depending on how small the gap is.
It is really hard to make a crank, never been done before and space age technology.
i snapped a crank set in the mid 1980s, first the drive side and exactly 1 year later, the non drive side . the cranks were italian, a company called Cambio Rino, then I switched to ultegra
It’s just adhesive TMF cracking from thermal and load cycling. The corrosion is a secondary effect of bond line failure and boundary infiltration.
Cleaning solvents may be breaking down the adhesive?
Only ever to me with Campag Record chainset, was a massive Campag fan boy, never had a prob since changing to Shimano.
I actually snapped my Shimano Hollowtech 105 crank axle about 2 years ago just before its bonded into the spider. I would add a photo if I could however I could send you one if you want to see it and explain how and where I did it in the UK.
Ive changed shimano to single plate doval and i cant sense any flex and the weight is 30 grams more on dura ace 9100. Also, aren't dura ace axle spindles alloy?
If it's sealed in water vapor, then colder climates would not be immune to the problem and would probably accentuate it.
If meniscus effect then maybe that would correspond more to wetter climates (so tropical), but then why is it also not more frequent in notoriously wet northern countries (like the UK)?
Nice video though. Appreciate the thoughtful analysis
great video, I will probably not have to worry about this problem but in the future I'll try to store my bike in my apartment and not the garage and use GT85
I wonder if these cranksets have a pressure/moisture relief type vent hole in them
You talked about the garage storage, I think in Asia lots of people also storing their bike on their balcony. Cold AF in winter and then hot as balls in the summer sun.
Even over a single day between night and day on the sun there is a substantial temp difference.
Good point Joe. Asian balconies EAT aluminium. Especially bars. I only put mine outdoors when im particularly pissed off with it...my nrw TCR lives in a de-humidified room 😉
Regarding heat and humidity, spending 2~3 weeks in the ocean, enclose in ocean containers certainly won’t help.
If they spray the cavity with foam, maybe that will minimize air volume while keep the weight down.
I've had two ultegra 6800 right crank arm failures on my cx bike, in about 7000 miles, the second cranked failing within 2years and about 2000 miles max. This is Scotland. I know at least a dozen of my 100 followers on strava that live within about 20 miles that have all had at least one failure as as well ... almost all were 6800, although there were a couple of durable ace as well. I've switched to 5800 as its a solid crank I believe.
I've had a 6800 fail here in Northern Ireland - so cold and damp most of the time!
I’ve seen three crank failures local to me in Scotland. All 6800 Ultegra models, two of them from the club I’m in, and another when I passed another cyclist who was walking along the road after his cranks failing.
Yikes, I live in that tropical zone. In a super high moisture area and that combined with dirty roads and fine sandy dirt on them is really tough on parts, especially bottom brackets. as for the cranksetm I have 105, whew
Microbial induced corrosion might possibly also play a role. It also follows your loose correlation between failures and geographic location.
Does salt on the roads have anything to do with this? I live in Greater London/Surrey and my 6800 cranks failed like this.
Interesting. Salt definitely could be an accelerator!
My DA9000 split apart a couple of years ago, started off with clicking on each peddle stroke the whilst investigating it literally fell in two, it had done dry miles only and looked in tip top condition, I live in England.
I work in a bike shop, have done for over 20 years. I have never seen this happen to any Shimano chainset
I've worked in bike shops for the last 23 years. The bonded Hollowtech 2 arms mostly 6800 and 9000 series, fail. I've seen mostly rights. About twenty, give or take. Corrosion related, every one, but still shouldn't be happening. All had corrosion around the spider/chaining interface and all had rusty stem bolts, rusted front derailleur parts, very smelly bar tape.
Mid-Atlantic, DC area, if it makes a difference.
@@n0ch91c3s im based in london. If the bikes are in that condition it cant really be deemed as a manufacturing fault. Light weight race compents need to be cleaned and maintained or they will fail
@@gclh22 I totally understand. It's one big reason why I'm on the fence about how I feel about it. On the one hand, it's definitely from some level of neglect. On the other hand, this is SHIMANO. They hold themselves to a higher standard and so do we. It happens to Dura Ace, the Ace of Durability. Also it only happens to their bonded arms. Although I have seen the occasional fracture of their previous welded Dura Ace and XTR, it was much much more rare and not from corrosion. Also the failure mode was gradual, not catastrophic.
The old Dura Ace 7703 cranksets have 3mm thick sidewalls and were laser welded together. An engineer at Speciality Race Products told me, that the fatigue resistance of XTR crank, of that generation, was well beyond was necessary. And what did we see about 20 years later, much lighter cranks. You would be better served by a map of ambient humidity. If humidity is the problem, then anywhere along the sea coast would be a problem. I know people who go out in ride in -8C, would that cycles of temperature extremes not cause more problems than tropical climates? Could be simpler, on very humid days there could possibly be a bonding problem.
You are onto it mate.Has anyone been badly hurt yet.Needs total redesign.Lack of proper pre release testing.Interesting.
Very interesting. 🤔 condensation is inevitable. Especially in coastal towns high salt content in the atmosphere. Untreated surfaces will oxidize. Leaving your Air conditioned apartment for a ride on the board walk on a humid day can accelerate the process.
I m sorry but this shimado theory about condenstiona/umidity is b.s.!!!
@@leofonte whats your take. Alot of ppl on fb have posted pics.
I've had two come in, both bringing to people who live in areas with salt water spray corrosion issues
There's a point where decreasing weight starts to compromise strength and longevity for the current state of technology. So nothing to complain about in my opinion. Just sacrifice the few grams and get a solid crank.
What would be a good substitute for an ultegra/dura ace crank? I'll just add shimano chainrings to it
One thing about the failures in that instagram account is that people with broken parts tend to post their experiences online, so of course that instagram account, where the failure cases are concentrated, makes Shimano's failure rate look "a lot". Those with long-lasting Shimano cranks like me or you would just go on with our rides and thus not being vocal about it. As the other comment said, a quantification of the failure rate is needed and then we can see whether it is acceptable or not.
The air inside is not sealed in on 6800, it’s open to the inside of the axle, gladly letting moisture in.
For interest's sake, my Ultegra 6800 failed in the same manner. It had been ridden in Melbourne, Australia for ~8yrs and >10,000km
I have Dura Ace 9000 from 2013,no issues in sunny ☀️ hot south Florida
I feel I'm taking an online engineering class LMAO. Great video!
Just wondering why we're not seeing the same issues with Cannondale SiSl cranks, don't they use a similar clam shell construction? I know the chainring construction is different but the cranks are similarly constructed?
Maybe much smaller quantities manufactured by orders of magnitude?
Hydrophobic paint?
GE silicone compound + mineral spirit, to a consistency suitable for spray nozzle.
Only good for fresh crank out of the box.
Hydrophobic reliability issue if apply after mileage built up or ran on wet road.
The most difficult part is availability on radial spray nozzle mounted on a straw.
If they transferred manufacturing somewhere else then there may be some shortcuts in the manufacturing process. It would be good to know from which manufacturing site these products came from. Excellent manufacturing companies are able to trace this back through product codes. The best manufacturers know on what day, shift, and production line the defective product was made.
Then again, it could also be a marketing tactic of a rival brand or another brand that would like to enter into the category.