Chinertown
Chinese Carbon Road Bikes => Road Bike Frames, Wheels & Components => Topic started by: jonathanf2 on August 18, 2025, 11:38:12 AM
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I don't have all the details yet, but my contact in China just sent me some news that a local cyclist died using the Magene QED groupset. After doing some independent tests, they found it was most likely due to design defect with the Magene shifters. The details I was given was that the cyclist was over 100kg, while using lightweight rotors, resin pads and was on a 5km downhill. They repeated the tests using the same rotors, brake pads and Magene calipers, but using Shimano shifters and it appears the Shimano shifters still worked at the high temp extremities. The fault lies with the Magene hydraulic brake shifter design.
The other news I heard is that Magene's groupset has been outselling LTwoo and Wheeltop combined. Not sure there will be a recall though. ::)
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Im not sure how the shifters would be the part that fail when the brakes get hot on a decent?
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Im not sure how the shifters would be the part that fail when the brakes get hot on a decent?
My contact and I communicate using a translator, so things might get mistranslated. From what I gathered in our conversation, the fault lies with Magene. Apparently they already financially settled with the family of the deceased. Like I said, I don't have all the details and it seems to be big news over there with cyclists, because my contact blew up my chat inbox with this story.
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Thanks for the heads up!
But..... a 220 lbs rider, resin pads, long descent. any resin pads will be soft and lose a big part of its braking power if the rider is not that experienced.
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Thanks for the heads up!
But..... a 220 lbs rider, resin pads, long descent. any resin pads will be soft and lose a big part of its braking power if the rider is not that experienced.
Yeah, that's a recipe for disaster. It's something Magene didn't anticipate for and it's put considerable heat on them. As my contact told me though, Shimano is huge over there, with SRAM taking a distant 2nd place (more popular for MTB). The rest of the domestic groupset brands have less than 3% marketshare from what I've been told.
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Yeah, that's a recipe for disaster. It's something Magene didn't anticipate for and it's put considerable heat on them. As my contact told me though, Shimano is huge over there, with SRAM taking a distant 2nd place (more popular for MTB). The rest of the domestic groupset brands have less than 3% marketshare from what I've been told.
I was in Shenzhen, China for a business trip a month ago. It's one of the richest Chinese place. I rode a shared bike (single speeder) along their bike trails for half a day and had only spotted 3 Chinerbikes. Most people were riding the western brands like we do, Cervelo seemed to have a big following there and then Specialized and Trek. And I don't see any L-Twoo nor Wheeltops. Those 3 Chinerbikes I saw were all equipped with Shimano 105 mechanicals.
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Ug that's sad to hear. A lot of bike parts coming out of China don't seem to be designed for anyone over 100kg :/ Every time I hear someone ask what to get for a bigger rider, my brain goes "uhhhhhhhhh" and I come up blank. 100kg isn't even that big, especially if you're tall.
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I was in Shenzhen, China for a business trip a month ago. It's one of the richest Chinese place. I rode a shared bike (single speeder) along their bike trails for half a day and had only spotted 3 Chinerbikes. Most people were riding the western brands like we do, Cervelo seemed to have a big following there and then Specialized and Trek. And I don't see any L-Twoo nor Wheeltops. Those 3 Chinerbikes I saw were all equipped with Shimano 105 mechanicals.
But is this a good place for a comparison? It seems like going to Monaco and saying europeans mostly Hypercars and you rarely see a BMW or Audi. But when you do it's almost a M or RS.
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But is this a good place for a comparison? It seems like going to Monaco and saying europeans mostly Hypercars and you rarely see a BMW or Audi. But when you do it's almost a M or RS.
sorry for the miscommunication. I was just sharing what I saw. Most people on this forum have never even been to China.
Also, Shenzhen is not a small place and it's way way way larger than Monaco (population 40,000 people). Shenzhen alone has 15 million people, almost a quarter of the entire country of France (68million).
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Damn, new fear unlocked. Anyway It's looking increasingly likely that Magene may not be interested in bringing this to market outside of China anyway.
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Ug that's sad to hear. A lot of bike parts coming out of China don't seem to be designed for anyone over 100kg :/ Every time I hear someone ask what to get for a bigger rider, my brain goes "uhhhhhhhhh" and I come up blank. 100kg isn't even that big, especially if you're tall.
Yeah it's a major oversight from Magene, especially since they had a lot of domestic hype over their groupset. I have a buddy over 100kg or about about 250lbs, ex-college US football player. I told him, don't even bother looking at or considering any of my lightweight bike parts. He rides either titanium or steel bikes and doesn't even touch carbon. This a dude who bent his 1x gravel chainring due to his weight and power output!
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https://www.youtube.com/watch?v=ZZtM4w3Qhsw
Indepth video from Petr
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I am a weird human.
$600 Chinese frames in general don't really scare me. What does terrify me however are:
-Ultra light cheap frames
-Ultra light cheap saddles
-Ultra light cheap handlebars
-Ultra cheap Chinese wheels
-Chinese groupsets
Basically all the touch points on my bike builds I give priority to over the frame itself. Wheels, tires, cockpit, and especially groupset. Like I said...I'm weird.
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I am a weird human.
$600 Chinese frames in general don't really scare me. What does terrify me however are:
-Ultra light cheap frames
-Ultra light cheap saddles
-Ultra light cheap handlebars
-Ultra cheap Chinese wheels
-Chinese groupsets
Basically all the touch points on my bike builds I give priority to over the frame itself. Wheels, tires, cockpit, and especially groupset. Like I said...I'm weird.
You forgot for "weird" :
- Sold a SL8 for a Tavelo ;).
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Indepth video from Petr
I went back to read the messages from my Chinese contact, I guess the cyclist who crashed survived. I tend to skim the details!
My contact also said they tested other Chinese groupsets under the same extreme conditions as Magene's QED. All passed the stress test, though LTwoo's system started leaking mineral oil. :(
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I went back to read the messages from my Chinese contact, I guess the cyclist who crashed survived. I tend to skim the details!
Come on man. There's a massive difference between a rider losing their life vs. what's actually happened here.
"I tend to skim the details" then make shit up and post absolute crap on a global forum to instil fear in people for what? Likes?
You sir are a royal muppet and I'm a muppet for sharing your post to other riders (as well as a cyclist in the industry) who are excited about trying the Magene groupset. Do better, please.
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Agreed. This is a huge oversight on your part to rush and share something so serious without, at the very least, reading it closely first.
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I have a guy sending me messages in Chinese that get translated to English and sometimes poorly. I have to use a translator to read each message. Either way the dude still ended up in the hospital with broken bones. As detailed in the video, Magene's shifters didn't fully engage pistons on worn brake pads on independent tests from authorized Magene mechanics.
Next time I hear news of a life threatening bike component, I'll make sure not to say anything. ::)
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Since the person that crashed was using a lightweight rotor, is there any information stated where they took a close look at his rotors to see if they were by chance glazed due to a combination of heat and some sort of surface contamination? I recently experienced on one of my rotors that it was glazed, and I had to use sandpaper and rough up the surfaces in order get the brake pads to stop the bike. In my case, the pads are resin, and were only 1/2 way worn. Kinda of spooky to pull the brake lever super hard without them bottoming out and have no stopping power.
Some of this story reminds me of a problem I had with my Wheeltop EDS TX brake levers that for some unknown reason would lock up solid at the levers. After this happened 3 times, and I came very very close to crashing on a descent, I replaced them. Wheeltop had no interest in helping me to discover why this was happening. (I believe that the pistons in the lever housing jam somehow. The levers are still sitting in a parts bin.
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Magene sent a technician to inspect his bike while he was still in the hospital and bought him a wheelchair. Magene cited worn resin brake pads(they still had lots of braking material left) on lightweight rotors and the groupset not being installed by an authorized service center. Magene said once the brakes were bled and had new pads, the brakes worked fine.
The rotor brand released testing showing that the resin pads work fine on their lightweight rotors with resin pads worn all the way down. Pads shouldn't fail in an on/off way. When the pad is worn off, the calipers should still squeeze the metal backing plate against the rotor and slow you down while squealing to warn you.
There are videos of mechanics showing that the QED calipers don't grip the rotor when worn down completely, while SRAM, Shimano, and LTwoo calipers do. Perhaps calipers without enough travel + a poor DIY bleed + half worn resin pads + lightweight rotor = randomly losing your brakes?
Video overview with a chinese speaker where I got this information from:
https://www.youtube.com/watch?v=ZZtM4w3Qhsw
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This is some scary shit. The levers don't displace the fluid needed to actuate the brakes properly, or the design doesn't allow for pads to advance as they wear properly. I would heavily bet on the latter, but there could be many causes. One is simply that the bladder isn't flexible enough and requires more vacuum to maintain its displaced state than the the system can hold (e.g., the system is not well sealed compared to the bladder's static properties). In practice, all of these systems require some air to be present in the system, as otherwise, a perfect bladder material would be needed; however, you also don't want too much air. It's also possible that the system is consistently hard to bleed, but that seems unlikely. Further, the videos showing that the mechanics can easily replicate this in the stand suggest it's a design issue. This would be a recall if it were to happen in the US or EU.
Perhaps Magene recognizes that they have some product design issues to address, which is why they decided to focus on China before entering those markets where regulators and consumers have historically been less forgiving. I hope the chinese cyclists continue to hold them accountable and that they roll out fixes, etc.
Some of this story reminds me of a problem I had with my Wheeltop EDS TX brake levers that for some unknown reason would lock up solid at the levers. After this happened 3 times, and I came very very close to crashing on a descent, I replaced them. Wheeltop had no interest in helping me to discover why this was happening. (I believe that the pistons in the lever housing jam somehow. The levers are still sitting in a parts bin.
Your type of failure, though no less scary, is more common. While it is also possible that the levers are physically jamming, I expect someone else to have observed this issue and replicated it, especially since you experienced the problem with both levers. The lack of return is likely due to the design of the wheel top system. Still, I wouldn't immediately consider this a design issue that needs a recall, as it could be an installation issue, bleeding, or even a case of using the wrong hydraulic fluid--conditions potentially which make the wheeltop design a poor one to avoid buying, but not a dangerous one.
I guess what I am saying is that your wheeltop issue was bad, but this is next-level bad.
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Were the test on other brands of brakes with the whole braking system, including the levers, or was it a swap of calipers with Magene levers?
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Were the test on other brands of brakes with the whole braking system, including the levers, or was it a swap of calipers with Magene levers?
There is both in the video. A lot of B-roll footage shows Chinese mechanics sanding down brake pads and testing them, demonstrating that even in the stand, the Magene ones still have a gap between them. They tested a Magene lever with an Ultegra caliper and it also had the same problem.
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Ah my bad, haven't got around to watching yet, will shut up until I do
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I have a guy sending me messages in Chinese that get translated to English and sometimes poorly. I have to use a translator to read each message. Either way the dude still ended up in the hospital with broken bones. As detailed in the video, Magene's shifters didn't fully engage pistons on worn brake pads on independent tests from authorized Magene mechanics.
Next time I hear news of a life threatening bike component, I'll make sure not to say anything. ::)
Maybe try use Deepseek(or Chatgpt) for translations. It will do a much better job than any translator app
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The way there are some people excusing it in youtube comments is kinda crazy to me too
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From my experiences with magene products, I often find them unpolished (but dangerous like that is a first...), dogshit customer support or just with asshole proprietary designs. None of their stuff looks too good to me, it's baffling that they're seen as one of the more trustworthy chinese companies. I'm already avoiding their products but I had serious hope they would give us some much needed competition as Ltwoo is getting too comfortable too. Looks like real progress will take some more time.
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From my experiences with magene products, I often find them unpolished (but dangerous like that is a first...), dogshit customer support or just with asshole proprietary designs. None of their stuff looks too good to me, it's baffling that they're seen as one of the more trustworthy chinese companies. I'm already avoiding their products but I had serious hope they would give us some much needed competition as Ltwoo is getting too comfortable too. Looks like real progress will take some more time.
Marketing is powerful stuff. They have an actual US storefront and their product pages use proper English and not auto-translated gibberish. That's basically all you need to look credible.
I've never had trouble with my LTWOO groupsets but keeping up with all their revisions and lack of support is tedious. I'm hoping Wheeltop keeps improving because on paper their groupsets are everything I'm looking for.
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You really should edit or take down your original post.
If I were Magene, I’d already be thinking about sending you a legal notice.
There’s a huge difference between death and injury, you need to be very careful with your wording.
Throwing around unverified claims like that could easily land you in serious legal trouble. ::)
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IDK, I imagine Magene’s legal team has bigger fish to fry right now. I still cant wrap my head around how this happened other than thinking they made a late material or design change and didn’t retest even basic scenarios.
That said—In the spirit of transparency, I would also edit the previous post from death to “almost died” or “had serious injuries” or something that is actually truthful.
I am pretty cavalier with mixing and matching parts on my own builds, but NGL, this has me wondering whether its a good idea to use aftermarket calipers to finish off my LTK266 build or if I should just stick with the boring sram ones.
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So the root cause seems to be that the reservoir in the lever is too small and basically runs out of fluid if the pistons are pushed out enough. That's REALLY bad and completely unrelated to rotor type, weight of the rider or anything else. I'm pretty sure that an engineer figured that out in development, but a manager in turn ignored or downplayed the problem. After all, design iterations late in development are expensive...
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So the root cause seems to be that the reservoir in the lever is too small and basically runs out of fluid if the pistons are pushed out enough. That's REALLY bad and completely unrelated to rotor type, weight of the rider or anything else. I'm pretty sure that an engineer figured that out in development, but a manager in turn ignored or downplayed the problem. After all, design iterations late in development are expensive...
Meaning the noise about lightweight rotors, heavy rider and long descent is just noise. Wouldn't this failure happen every time you wear the pads down?
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Not necessarily if you bleed your brake regularly…
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Meaning the noise about lightweight rotors, heavy rider and long descent is just noise. Wouldn't this failure happen every time you wear the pads down?
Imagine even if you have some worn out rotor on the edge of replacing 1.5-1.6mm thickness (1.8mm is new rotor thicknes), then you would lose braking even sooner on brake pads wear.
For me this is completely on megene and unbelievably stupid engeniring mistake, there needs to be some safety faktor on every component especially on brakes, basically you need to be able to stop on absolutely destroyed pads and rotors no problem (like with shimano and sram) and absolutely nothing other is acceptable.
The amount of absolutely destroyed brakepads to metal and cooked rotors I have seen in my bike shop is unbelievable, people just dont care about bikes that much and if I imagine that every one of those people would loose their brakes with very high chance of crashing is scary.
It will be interesting to see how this will end up.
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TraceVelo just dropped a video on the issue:
Basically, testing other groupsets, repeating what was said in Petr's video, then reading a statement from his contact at Magene in which they insist it's not an issue with their product
https://www.youtube.com/watch?v=AK3V_emmGkI
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I asked Luke when the statement came out, and he confirmed that the statement insisting it's not an issue with the QED groupset was sent over yesterday (The 27th), which is after mechanics on social media posted testing showing the calipers not closing all the way.
Me:
When did your contact send you the statement? Iirc there was testing by a technician while the victim was in the hospital, followed by an initial statement from Magene blaming the pads and bleed. Then, all the testing pointing the finger at Magene came out, and there hasn't been a response since then. Is that statement from Magene you read from after the testing on social media was posted?
Luke:
I got the statement yesterday (27th August), so it's pretty fresh. As mentioned, once those additional details of their investigation come out, I'll post everything I can in the comments. By that point, it should be clear what Magene's position is, but from what I've been told, they are adamant it's not a problem with their groupset. I'd freaking love to test it myself though....
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The only thing that doesn't make sense is both brakes failing simultaneously. I don't know anybody who wears their brake pads equally.
Out of interest what thickness discs do Magene specify? Minimum thickness for different brands of MTB discs can vary from 1.5mm to 2.0mm, generally 0.3mm from their starting thickness.
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Ah man this is really confusing now, and compounded by the fact that none of us can get our hands on this groupset to do our own testing.
A good mate of mine has been waiting for this groupset to hit the market for months (he has a Velobuild frame and all parts ready to go, just waiting on this groupset) and when I sent him the video he was so frustrated that he hit the buy now button on a Shimano 105 Di2 groupset (in reality, not a bad decision).
But if Magene is right, then maybe he could have waited this out? Doesn't negate the testing videos that some of the Chinese mechanics did though, so what is it?
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Ah man this is really confusing now, and compounded by the fact that none of us can get our hands on this groupset to do our own testing.
A good mate of mine has been waiting for this groupset to hit the market for months (he has a Velobuild frame and all parts ready to go, just waiting on this groupset) and when I sent him the video he was so frustrated that he hit the buy now button on a Shimano 105 Di2 groupset (in reality, not a bad decision).
But if Magene is right, then maybe he could have waited this out? Doesn't negate the testing videos that some of the Chinese mechanics did though, so what is it?
This failure is super weird. The mechanics in the videos have shown that the issue is with the shifters not the calipers and honestly as far as I can tell ruled out an abnormal bleed by the injured person. The amount of fluid needed to advance pads is really small. Volume wise its less than a pump of the lever, it seems unlikely that the reservoir really is too small to manage that. There has to be some sort of pressure issue either caused by air in the system that gets forced into the lines or by the bladder / valve assembly that draws more fluid in. I still think its a design issue, but I concede that it could be some sort of maintenance error. However, if it is a maintenance issue, its a mistake mechanics and owners are making over and over again to get to this kind of consistent result. Something like bleeding issues or water in the lines should not be consistent enough to replicate what we are seeing. Perhaps people are using a popular off brand or wrong brand mineral oil that's a different rating / viscosity than they are supposed to use? Or maybe everyone is using aftermarket pads that have less backplate than they should? Both of these seem somewhat unlikely unless both are Shimano or some similarly popular aftermarket products that appear compatible but aren't.
Either way, I personally would not buy this product until there are more clear answers or at least a demonstration of the pad advance working and a guide on what not to do to ensure proper operations. In the worst case, Magene tries to gaslight everyone into thinking this is what their intention is and that this is what proper, safe, brake should be. In which case, we should warn everyone against using any Magene products. Period.
I am 100% going to test with this with my aftermarket Hope brakes on my SRAM levers out of sheer paranoia now.
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Coming from MTB, there might be parallels to the tinkering solution called "Shigura" which describes Shimano brake levers paired with Magura calipers. The problem is that the calipers need much more oil volume than the shimano ones (and compounding that, Magura has 2.0mm brake rotors compared Shimano's 1.8mm), so the reservoir in the levers is too small. So if you use a Shimano rotor and the brake pads (or/and disc) are worn, you are getting to the point that you can no longer build up pressure, because you run out of oil. The tinkerers running this combo normally are aware of this and often bleed the brake at like half-pad-wear (actually overfilling the brake - resetting it like this would pop the reservoir) to not run out of braking juice. So yes, too small a reservoir can lead to brake failure.
That said, I agree that both brakes failing at the same time is still strange. It might be that one brake stopped working properly, leading to the rider compensating and overusing the other one and actually boiling the liquid or destroying/glazing the pads. But that's pure speculation.
At any rate, any trustworthy company would launch a serious investigation after something like this happened. On the other hand, in days of social media and viral stories destroying companies/lives with little regard for truth, I can somewhat understand Magene's "official" reaction to not react in any way that could construed as an admission of guilt. If this happened with Shimano and Sram groupset, they wouldn't react with "Yeah, might be our fault". How long did it take Shimano to admit their cranks were falling apart? I would expect that internally, they are looking into this really carefully, but maybe I'm just naive. Time will tell.
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Coming from MTB, there might be parallels to the tinkering solution called "Shigura" which describes Shimano brake levers paired with Magura calipers. The problem is that the calipers need much more oil volume than the shimano ones (and compounding that, Magura has 2.0mm brake rotors compared Shimano's 1.8mm), so the reservoir in the levers is too small. So if you use a Shimano rotor and the brake pads (or/and disc) are worn, you are getting to the point that you can no longer build up pressure, because you run out of oil. The tinkerers running this combo normally are aware of this and often bleed the brake at like half-pad-wear (actually overfilling the brake - resetting it like this would pop the reservoir) to not run out of braking juice. So yes, too small a reservoir can lead to brake failure.
That said, I agree that both brakes failing at the same time is still strange. It might be that one brake stopped working properly, leading to the rider compensating and overusing the other one and actually boiling the liquid or destroying/glazing the pads. But that's pure speculation.
At any rate, any trustworthy company would launch a serious investigation after something like this happened. On the other hand, in days of social media and viral stories destroying companies/lives with little regard for truth, I can somewhat understand Magene's "official" reaction to not react in any way that could construed as an admission of guilt. If this happened with Shimano and Sram groupset, they wouldn't react with "Yeah, might be our fault". How long did it take Shimano to admit their cranks were falling apart? I would expect that internally, they are looking into this really carefully, but maybe I'm just naive. Time will tell.
SRAM did a recall over too much Loctite. Shimano's crank recall, well, that's not really the example we should be wanting Magene to follow. Pretty sure they had to settle for more expansive terms on their recall than they wished to due to a class action lawsuits in the US, including one that is still being resolved.
Regarding the Shigura MTB, that's a tough one because Magura MT5/MT7 calipers require 15% more volume than the SLX does, and Gustav is around 60% or so. In that case, it's not just that the reservoir is too small, the master cylinder is also very undersized. The natural solution to this would be to reduce pad clearance. Still, as you pointed out, the size of the rotors and the design of the calipers make this more challenging to execute compared to aftermarket brakes with oversized pistons, such as Trickstuff's C22, or four-pot brakes like the Hope Rx4+. Even still, this kind of failure isn't something I have heard of relative to those conversions.
It's also unfair to compare people hacking together an aftermarket solution to a 100% in-house designed one like Magene has here.
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According the Peak Torque's latest video Shimano cranks that were replaced after the recall are cracking again. Will be interesting to see how Shimano responds.
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It's also unfair to compare people hacking together an aftermarket solution to a 100% in-house designed one like Magene has here.
I didn't mean to compare someone using a groupset as intended by the manufacturer with the tinkering of shigura - that's why i said that those tinkerers are aware of the.. limitations. Still I remember reading from someone who had to abort his ride and limp home because his brakes were getting really weak...
I only wanted to make the point that a too small reservoir, especially if maybe some other conditions happen to be met, can indeed lead to brake failure. Magene should absolutely design their system that this is impossible though and that's hardly rocket science - I'm looking forward to hopefully conclusive findings on what happened some time down the line.
On recalls: Kudos to Sram for owning their mistake then, that makes me feel reassured as I'm mostly using their stuff - the example of Shimano was just to illustrate that it's not an exclusively Chinese/Magene thing to go "No, there's nothing wrong" and putting people's health at risk with it. Now reading (thanks for the info Justin) it's actually now happening again just leaves me speechless.
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Oh they've been failing, I've had some pics of a cracked 9200 crank for long enough to have forgotten where I got them.
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https://www.youtube.com/watch?v=iOtECmH9aCU
Magene tried pads worn to the backing plate on a different QED groupset with a proper bleed, and the brakes worked
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So why is it that it worked for them, and not the other independent mechanics and why do they not want to release any video to prove them wrong? Frankly I don't buy their excuse of not wanting to encourage improper use.
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magene's report has been translated to english here:
https://imgur.com/a/magene-qed-braking-test-report-ynboGn7
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That's great and all, but it only addresses the situation which led to the accident, not the problems that were found independently after the fact.
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I have absolutely no stake in this, so this comment is purely academic.
Magene’s report basically says *we tried to replicate this and we couldn’t* and also *we looked through our reports on manufacturing quality and saw no potential issues that would cause this*.
Their conclusion though that therefore this must be user error is far from airtight, though it’s possible. If for legal reasons, the cyclist wants to ensure his groupset can be used as evidence in a lawsuit/ some sort off regulatory action; Magene should be inspecting the test units from those independent mechanics to understand what they are doing that led to the replication of this issue. This could still be a manufacturing quality issue or a design issue there envelope for the correct specs was made too wide and parts that meet spec when assembled together don’t always perform as expected.
This also could be widespread user error. We have seen it before with the Sram FDs: its very possible to publish detailed videos, make specific setup tools and still have large numbers of users and mechanics fail to set things up properly because they are on autopilot and doing what they are used to for Shimano. However, I also think that that issue *should* have been more aggressively addressed by Sram and given this on brakes should also be aggressively addressed here too.
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From my perspective... If I was Magene, the first thing I would have done is go back to my Engineers and take a look at the brake system design. I would double and triple check that the basic design is mathematically sound, and has a built in "performance safety factors". Then I would take a look at all of the machined parts tolerance studies versus actual machined parts QA reports and perform a quick machined parts tolerance stack to determine if there is any combination of assembled parts that could be put together that would cause a 1 in XXX failure rate. Then I would look at how the brakes have to be bled versus how the "average mechanic of hobbyist" would bleed the brakes. (What effect do small bubbles, or air intrusion have on the function of the design.) Can air bubbles accumulate or migrate to a place in the system that will reduce performance or cause a massive failure. I would also look at thermodynamic tests and what effect heat has on the brakes. Thermal cycling versus brake fade and what happens under long continuous heat loaded braking.
With all of this information/data in hand and understood, I would then defend my product accordingly. My public response would be based on my internal findings.
If my ducks are all in a row, then I would take one approach, versus if I discovered that my product was lacking in an area, I might take another approach/response. If they have cut corners somewhere in the part quality and machined part tolerances such that there is a 1 in (some tolerable to them failure rate), then I might be more arrogant in my defense of the design and blame the user, while I tighten up QA of the assembled system and quietly fix the very small problem, versus if I discover I have a substantial problem on my hands , a different approach may be used.
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Coming from MTB, there might be parallels to the tinkering solution called "Shigura" which describes Shimano brake levers paired with Magura calipers. The problem is that the calipers need much more oil volume than the shimano ones (and compounding that, Magura has 2.0mm brake rotors compared Shimano's 1.8mm), so the reservoir in the levers is too small. So if you use a Shimano rotor and the brake pads (or/and disc) are worn, you are getting to the point that you can no longer build up pressure, because you run out of oil. The tinkerers running this combo normally are aware of this and often bleed the brake at like half-pad-wear (actually overfilling the brake - resetting it like this would pop the reservoir) to not run out of braking juice. So yes, too small a reservoir can lead to brake failure.
That said, I agree that both brakes failing at the same time is still strange. It might be that one brake stopped working properly, leading to the rider compensating and overusing the other one and actually boiling the liquid or destroying/glazing the pads. But that's pure speculation.
At any rate, any trustworthy company would launch a serious investigation after something like this happened. On the other hand, in days of social media and viral stories destroying companies/lives with little regard for truth, I can somewhat understand Magene's "official" reaction to not react in any way that could construed as an admission of guilt. If this happened with Shimano and Sram groupset, they wouldn't react with "Yeah, might be our fault". How long did it take Shimano to admit their cranks were falling apart? I would expect that internally, they are looking into this really carefully, but maybe I'm just naive. Time will tell.
I suspect they didn't actually fail at the same time. The rear likely failed first and the user didn't realize it as they likely used both levers when braking and the front brake is what you primarily feel and focus on modulating to avoid going over the handlebars.
The excuse Magene gave for not allowing Luke to show the video of the backing plates grabbing the rotor doesn't make a lot of sense. No judge is going to find Magene financially liable for a crash with pads worn down to the backing plates. Demonstrating a basic last ditch safety feature that exists on every other hydraulic braking system wouldn't change that, and would reassure us that if we're negligent, their brakes will warn us and do what they can to bail us out.
Additionally, not publishing the fluid volume(and brake line length) in the system doesn't instill confidence. How bad was the brake bleed? I've done a subpar brake bleed before which resulted in a bit of a spongy shimano lever. Would that bleed have taken out my brakes on the QED groupset? If the measured volume of oil was egregiously low, nobody would worry, knowing they could follow the Park Tools tutorial reasonably well. If this piece of information were published, we could also replicate the issue ourselves and be sure of the cause.
As it stands, it's still possible that this user
1) Picked some lightweight rotors that the brakes should be able to handle
2) Picked some official magene resin brake pads
3) Wore down said pads to a reasonable level for a hydraulic brake system to be able to handle
4) Performed an imperfect but not egregious bleed job.
If that's possibly the cause for totally losing your brakes flying down a mountain, I'll stick to my Shimano brakes. I like my resin pads, and if my LBS leaves a few bubbles in my lines I don't want my brakes to go out the before I even wear off the pad material.
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https://www.youtube.com/watch?v=iOtECmH9aCU
Magene tried pads worn to the backing plate on a different QED groupset with a proper bleed, and the brakes worked
I would REALLY like to know what their protocol for this test was.... If they put worn out (or partially worn out) pads on and THEN did the bleed.. no question the brakes should work --- because they compensated for the additional fluid needed.
From what I understand from the information released by "independent mechanics" (and the same method Luke tried on the systems he had) the protocol was Bleed with normal pads, replace with worn out pads and then see if the brakes work. Since probably most users are very unlikely to bleed their brakes on any sort of regular basis this would be a far more realistic test.
By the way as a word of background I am a mechanical engineer... I have been an engineer in failure analysis (semiconductors so admittedly a bit different) for the last 20 years.... have restored an antique car (1970 Triumph), do all my own brake work (cars / bikes etc) ..
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Besides this brake issue which has not recurred for anyone else, what are the opinions and news about Magene QED? Which would you choose among Magene / L-Twoo eRX eR9 / Wheeltop EDS-TX ? Or 105 Di2?
I watched a couple of videos on bilibili with ai translation and it looks really good.
https://www.bilibili.com/video/BV1vAs2zPErV/ (https://www.bilibili.com/video/BV1vAs2zPErV/)
https://www.bilibili.com/video/BV1ZcjJz3EpA/ (https://www.bilibili.com/video/BV1ZcjJz3EpA/)
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Besides this brake issue which has not recurred for anyone else, what are the opinions and news about Magene QED? Which would you choose among Magene / L-Twoo eRX eR9 / Wheeltop EDS-TX ? Or 105 Di2?
I watched a couple of videos on bilibili with ai translation and it looks really good.
https://www.bilibili.com/video/BV1vAs2zPErV/ (https://www.bilibili.com/video/BV1vAs2zPErV/)
https://www.bilibili.com/video/BV1ZcjJz3EpA/ (https://www.bilibili.com/video/BV1ZcjJz3EpA/)
I am invested in Wheeltop EDS systems in that I own 4 sets installed on bikes, one used set off the bike, and a second brand new set of TX series with hydraulic brakes. Posted in the EDS TX thread is the "close-as-it-comes" account of my original EDS TX hydraulic levers both locking up at the same time heading into a corner at luckily lower speeds in a pack, such that as I pulled on the levers, they froze/locked up and did not push fluid down to the calipers. I was able to get to the side of the other riders, go off the shoulder of the road, all the while pumping/forcefully pulling on the levers, then pop, they started working. This happened again a second time to both levers and at higher speed on a corner. They started working again just before I could have crashed. The third time only one lever locked up. I purchased a new set of TX levers from XZX Components. I installed them, and the RH lever wouldn't shift correctly, so Jerry replaced this lever. After replacing the original pair of levers, the brakes have worked perfectly for thousands of miles. The bad levers have been sitting in a box for the past year+.
I am having almost constant issues with my IIIPro E4 MTB brakes I started purchasing 3+ years ago. (Another thread on this forum.) I see parallel problems to what happened with my IIIPro brakes, and the OP, except I have been lucky and have only had one brake fail at a time.
I have gradually been studying, measuring and examining my failed IIIPro brakes. I listened again to the video posted in this thread. Based on my growing experience with my problem brakes, I believe that in the next month or so, I will have a Q&A spreadsheet put together that could help with some post-forensic study of the OP's original failure.
Every time I suffer another problem with my rear IIIPro brake, I believe I have resolved the problem, but then the brake fails again in a short period of time. I want to blame these brakes basic design, but then in theory, bicycle hydraulic brakes are actually a very simple design. Hydraulic brakes have been around since the 1920s for cars and the 1970s for motorcycles. Bicycle hydraulic brakes are scaled down motorcycle brakes.
So I ask myself, what is the differences between Shimano, SRAM, HOPE Tech versus contemporary Chinese based designs. To me, it ain't rocket science!
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So I ask myself, what is the differences between Shimano, SRAM, HOPE Tech versus contemporary Chinese based designs. To me, it ain't rocket science!
Hydraulic brakes are indeed relatively simple systems. Established Western brands have huge legal exposure and reputation risk if a brake fails, so they tend to over-engineer, over-test, and simplify wherever possible. Every design decision passes through layers of QA, failure analysis, and compliance testing before release. That sort of caution slows innovation but also removes a lot of unknowns
Chinese brands don't have the same incentives. There's less material liability in China, and there's significant cultural differences between the west and east. You begin to pick up on it as you develop relationships with OEMs and brands. You could sum it up as China having an engineering heavy culture, whereas the west has a litigation heavy culture. Working as a western engineer, every team I've been on has naturally developed a culture of speaking your mind and playing things safe. There's nearly as much clout in stopping something for good reason than creating something
Ultimately this is a broad generalization, and China regularly releases great products, but I think it's an important answer to your question
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So I ask myself, what is the differences between Shimano, SRAM, HOPE Tech versus contemporary Chinese based designs. To me, it ain't rocket science!
You say that but for mtb brakes Shimano have the wandering bit point problem and their callipers seem prone to leaks. For SRAM the code brakes have problems with the plastic part in the master cylinder swelling so the brake stops working.