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One of the kids on the mountain bike racing team team that my daughter is on has destroyed 4 derailleurs this season. He's riding a hard tail Specialized (mid level). I chalk it up to possible user error aka picking up a stick and not realizing it and immediately back pedaling to clear it. He did mention at the start of a race yesterday that his bike was shifting funny. I'm guessing perhaps the hanger was bent or weak which may have added to the failure of his derailleur yesterday. Is he just super unlucky? Or is there a way to minimize the risk? His mom's spent over $500 on derailleurs in the past few months and she's not happy...
 

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It's user error and most likely also mechanic error. Who works on the kids bike, do they really know what they're doing? Do they check the hanger and make sure it's properly aligned before installing a new derailleur? Agree, stop buying $100 derailleurs for a friking kid, move to a Shimano drivetrain and buy $50 SLX derailleurs, SRAM Eagle anything is WAY over priced.
 

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slap an R-tool on that bike and verify hanger alignment before chunking more money at it

also...mebbe swap to shimano...when my SRAM is running fine, it's great. but I've wreck 2 SRAM's JRA well before they were used up and worn out, and never wrecked a shimano der JRA ever (only stick mistakes ate my shimanos)

ya I know it's random and unpredictable, but I do believe shimano engineering counts for more than SRAM
 

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when I worked in a shop, there was ONE thing that destroyed more derailleurs on kids' bikes than anything else. And it didn't matter how expensive they were.

carelessness

Kids that were not taught not to lay their bikes down on the right side bent their hangers CONSTANTLY and then after picking them up, shifted the derailleur into the wheel and blew up the drivetrain. It's not immediately obvious that this is how it happens, but after seeing it so many times and talking to kids and parents, the pattern began to reveal itself.

Kids that are taught this, and parents who emphasize it don't generally have the problem. Sometimes kids are able to avoid it by pure chance. But eventually they've gotta learn. Shoot, a lot of adults need to be taught the same thing. It got to the point that whenever I sold a kids' bike to a family, I'd cover that before they left the shop along with stuff like quick release usage instructions, how to release vee brakes to remove the wheels, don't touch disc brake rotors, how to use a presta valve, etc. I'd always give the parents a look when talking about laying the bike down on the drivetrain because that one, more than anything, needs to be emphasized over and over before kids will get it.
 

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I've seen a problem with the 1X SRAM Eagle systems on a few occasions. The rider isn't prepared for the upcoming terrain, and they mash the multiple gear take up shifter to take multiple cogs in one shift. In this case the final gear is the big pie platter. The derailleur or hanger cannot handle it, and something gets tweaked. This upsets the limit settings and in a few short minutes the whole mess ends up in the spokes.

I think this is amplified by Specialized (and possibly others) designing the weakest hanger ever. The thru axle takes more meat off of the hanger via the bigger hole. They also dropped the additional retention screw a few years ago on many models. Look up how tiny they look.

While on a stand, try shifting multiple cogs with the biggest one as the final jump and see what happens. On one bike I fixed it with a SRAM shifer without multi-shift and an aftermarket hanger.
 

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Stop buying $100+ derailleurs for kids?
Kids are hard on stuff but I don't know that we should automatically blame them for this. I've seen a SRAM derailleur, which I knew was set up perfectly well, mangle itself. Bent hangers etc can cause issues but there is possibly more going on.

I don't know how they do it, I've looked at trashed derailleurs to try and figure it out, but for some reason SRAM derailleurs seem to be more likely to get snagged on the chain and kill themselves. Talking about derailleur alignment is a red herring. In normal use, the chain is fed into the derailleur cage from various angles and heights as it moves across the cassette but it doesn't catch. I've seen really bent hangers or derailleurs still running fine. They might not shift very well, maybe make a racket but they don't catch the chain.

I always find the accusation that the hangers aren't strong enough amusing too. They're not meant to be strong, that's the whole point! They're supposed to bend or break much more easily than the frame so that you need to replace a £15 part and and not a £400 part. The energy has to go somewhere and if the hanger is too strong you just break the derailleur or frame instead.
 

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Kids are hard on stuff but I don't know that we should automatically blame them for this. I've seen a SRAM derailleur, which I knew was set up perfectly well, mangle itself. Bent hangers etc can cause issues but there is possibly more going on.

I don't know how they do it, I've looked at trashed derailleurs to try and figure it out, but for some reason SRAM derailleurs seem to be more likely to get snagged on the chain and kill themselves. Talking about derailleur alignment is a red herring. In normal use, the chain is fed into the derailleur cage from various angles and heights as it moves across the cassette but it doesn't catch. I've seen really bent hangers or derailleurs still running fine. They might not shift very well, maybe make a racket but they don't catch the chain.

I always find the accusation that the hangers aren't strong enough amusing too. They're not meant to be strong, that's the whole point! They're supposed to bend or break much more easily than the frame so that you need to replace a £15 part and and not a £400 part. The energy has to go somewhere and if the hanger is too strong you just break the derailleur or frame instead.
I agree, the hangers need to be soft to protect the der and the frame.
I'm curious, are you talking about older Sram derailleus?
I'm on Srams derailleurs on many bike for about 2 years and no matter what I do to them they keep being strong.

I trashed 2 hangers last year on my park bike, but my GX Eagle didn't care.
I may still replace it since I don't really need an Eagle on my park bike.
Feels kinda overkill.
 

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It's a Specialized Chisel Expert (2019) with a Sram NX Eagle drivetrain. Not sure on the type of breaks...
Not surprised that a kid could have issues like this. Especially if it's a strong and aggressive kid. Maybe he (or she) needs to work on smooth power delivery during shifting and become more aware of what is going on before explosion occurs. 'Be one with your machine grasshopper!'

I have not been impressed with my GX Eagle 1X12 with respect to reliability. I like how it shifts but the 12spd setup hags very low and is a debris magnet. When it happens, the lower cog gets pulled into spokes to add to the joy. The NX is a step down in quality from the GX so it's even more prone to damage. Years of running Shimano 9spds and I never had these issues. Moving up in class to X0, XX1 is stupid expensive and I'm not going there.

Next failure I'm ditching the 12 and going with 11spd GX Eagle cassette (so I can still use XD hub). Slap on a tried/true Shimano M8000 11 spd (med cage) der and 11spd XT shifter. Losing the 50T granny may mean a smaller chain ring to get ratio's dialed for my terrain but the $110 derailleur replacements will be over.
 

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my eagle cage once twisted like a pretzel for no damn good reason.

my shimanos have never twisted a cage unless the der was already on the dead-end ride up around the cluster and ripping my hanger off at the same time

SRAM cannot fight off 'normal-ish' driveline chonking like shimano....sram tends to give up and bend ...again, no apparent reason other than pretty weak design. shimano can take some crud and fight off wonky loads and chain activity better in my experiences
 

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my eagle cage once twisted like a pretzel for no damn good reason.

my shimanos have never twisted a cage unless the der was already on the dead-end ride up around the cluster and ripping my hanger off at the same time

SRAM cannot fight off 'normal-ish' driveline chonking like shimano....sram tends to give up and bend ...again, no apparent reason other than pretty weak design. shimano can take some crud and fight off wonky loads and chain activity better in my experiences
I must be really lucky then :cornut:
 

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I don't think it is no reason. Pedal slowly and try a triple gear jump to the 50 tooth. About every 10th try the thing jams. A normal experienced person would stop when the resistance goes through the roof. An exhausted kid trying the climb of his life ... maybe doesn't even know it is happening.
 

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Incredibly strong anti-SRAM bias on this site I've noticed. I find it weird, but amusing.

I don't know, I ride in Arizona, which has some of the rockiest, most bike-destroying terrain around. I've had great success with most MODERN drivetrain setups; by modern I mean 11 speed and newer. I used to destroy three or four derailleurs a rear on older drivetrains.

Shimano is fine by me. If I buy a bike that comes with Shimano, I ride it. If I'm buying the drivetrain personally, I tend to go SRAM as I have a slight preference for the positive shifting and non-NX Eagle cassettes are awesome.

Eagle stuff IS more sensitive to hanger straightness and B-tension adjustment. With a kid maybe pushing too hard on an out-of-sync drivetrain, you could see it happening.
 

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I don't think it's anti sram bias. It's an eagle problem. XD is good stuff, and the 10-42 works great. It's just eagle that is sensitive and damage prone.

I suspect Shimano 12s will have similar issues. It's just too damn big.

If you can get away with 11s, I think it's the way to go.
 
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