Better hold off on the Magene QED electronic groupset

[zett]

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...

[cccccccccccccccx]

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?

[Ludo]

Not necessarily if you bleed your brake regularly…

[KRoser]

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.

[cyruscycles]

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

[cyruscycles]

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....

[gribs]

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.

[JustinFox]

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?

[Sakizashi]

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.

[R-J]

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.

[Sakizashi]

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.

[JustinFox]

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.

[R-J]

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.

[toxin]

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.

[cyruscycles]

Magene tried pads worn to the backing plate on a different QED groupset with a proper bleed, and the brakes worked