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Broken 105 Di2 Rear Derailleur

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Broken 105 Di2 Rear Derailleur

Old 02-21-24, 09:24 AM
  #51  
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Originally Posted by Kontact
if this happened.
Bingo.

If my skepticism is wrong*, there is a very simple fix: Put the QR lever on the other side of the fork.

Better yet, get those DT Swiss crank-on skewers where the spring-loaded lever can be positioned 90° from where it was when the incident occurred.

* meaning if it happened, it was most likely a loose external cam lever improperly closed and tightened, i.e., user error. To unlock a quick release, you have to apply a pulling force perpendicular to the wheel (or parallel to the axle).

Last edited by Polaris OBark; 02-21-24 at 09:32 AM.
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Old 02-21-24, 09:25 AM
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Originally Posted by Koyote
Do you know what "JRA" stands for?
This is my fault for using a TLA.
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Old 02-21-24, 09:38 AM
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OP -
You already replaced the part, so along with that you bought yourself tons of time on any warranty claim. One idea that has worked for me 100% in the past with different things is to send the broken part to them with a little note, and then ignore any future communication from them. Eventually what happens is they get tired of looking at it after awhile and just throw it out and send you a new one. This may take a few months longer, but you don't care.
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Old 02-21-24, 09:57 AM
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That is the beauty of Shimano. They keep chit-chat to a minimum.
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Old 02-21-24, 11:57 AM
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I just dropped the box off at the post office. We'll see!
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Old 02-21-24, 08:13 PM
  #56  
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Originally Posted by jgwilliams
Frankly, that's tosh. There's no point having QR if it's so tight it can't be undone by hand, and the angle was pretty much dictated by the design of the fork.
I don't know of any fork that only has one QR position, and it should take some strength to close a QR lever. So I stand by my point that QR lever should not be so exposed and loose to open with a misplaced kick. QRs are 90 years old - I have never heard of one being kicked open - but I have seen a hell of a lot of loose ones working as a shop mechanic.
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Old 02-22-24, 03:14 AM
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Originally Posted by Kontact
I don't know of any fork that only has one QR position, and it should take some strength to close a QR lever. So I stand by my point that QR lever should not be so exposed and loose to open with a misplaced kick. QRs are 90 years old - I have never heard of one being kicked open - but I have seen a hell of a lot of loose ones working as a shop mechanic.
You are very free with unhelpful opinions, such as 'it broke because it's plastic'. Some plastics are stronger than some metals, otherwise there wouldn't be so many carbon fibre planes, cars, boats and bikes. I've been riding QR for 50 years myself and it's never happened before or since. You don't know how hard I kicked it when my foot slipped off, just as you don't know how hard the OP kicked his derailleur when his foot slipped. I can assure you, I hit it with quite a bang and it jolly well hurt. You don't know the design of the fork. And yet you pile in with your uninformed opinion. I can assure you the QR was plenty tight enough. Back in the days of steel I would have had the lever pointing up behind the fork for the most protection. That wasn't possible with this fork. I reckoned that pointing backwards was the safest alternative, as pointing forwards or downwards had greater potential for catching on something, OK? I can't show you as the bike has now been sold and I now have thru axles.
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Old 02-22-24, 07:36 AM
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Originally Posted by jgwilliams
You are very free with unhelpful opinions, such as 'it broke because it's plastic'. Some plastics are stronger than some metals, otherwise there wouldn't be so many carbon fibre planes, cars, boats and bikes. I've been riding QR for 50 years myself and it's never happened before or since. You don't know how hard I kicked it when my foot slipped off, just as you don't know how hard the OP kicked his derailleur when his foot slipped. I can assure you, I hit it with quite a bang and it jolly well hurt. You don't know the design of the fork. And yet you pile in with your uninformed opinion. I can assure you the QR was plenty tight enough. Back in the days of steel I would have had the lever pointing up behind the fork for the most protection. That wasn't possible with this fork. I reckoned that pointing backwards was the safest alternative, as pointing forwards or downwards had greater potential for catching on something, OK? I can't show you as the bike has now been sold and I now have thru axles.
Why so upset? I pointed out that it sounds like there was a secondary cause - something you could correct to decrease the chances of a repeat.
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Old 02-23-24, 03:01 AM
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Originally Posted by Kontact
Why so upset? I pointed out that it sounds like there was a secondary cause - something you could correct to decrease the chances of a repeat.
Then try not treating people like idiots in the future.
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Old 02-23-24, 05:22 AM
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Originally Posted by Kontact
Why so upset? I pointed out that it sounds like there was a secondary cause - something you could correct to decrease the chances of a repeat.
It was more the way you said it chap
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Old 02-23-24, 07:33 AM
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Originally Posted by jgwilliams
Then try not treating people like idiots in the future.
Maybe he's actually the Bike Farmer?
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Old 02-23-24, 08:04 AM
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Originally Posted by jgwilliams
Then try not treating people like idiots in the future.
And how did I treat you like an idiot? By suggesting you made the same mistake I've seen others makes hundreds of times? Are those people "idiots" for not knowing how tight a quick release should be?

I sometimes wonder how people are able to navigate life when they get so upset about the suggestion that they could have done something wrong, or better.
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Old 02-23-24, 08:28 AM
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Originally Posted by Kontact
And how did I treat you like an idiot? By suggesting you made the same mistake I've seen others makes hundreds of times? Are those people "idiots" for not knowing how tight a quick release should be?

I sometimes wonder how people are able to navigate life when they get so upset about the suggestion that they could have done something wrong, or better.
I have sat in contemplation of this debate and can now offer my final judgement.

The response of "Frankly that's tosh..." could certainly be regarded as a little knee-jerk or defensive.

Having said that, "Your QR lever wasn't nearly tight enough or at a proper angle if this happened." could quite easily be interpreted as "you don't know what you're doing" and maybe just the subtle addition of "Do you think it's possible that..." at the start might promote a more collaborative discussion amongst respected equals.

Forum court is hereby adjouned. (gavel)
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Old 02-23-24, 09:32 AM
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Originally Posted by choddo
I have sat in contemplation of this debate and can now offer my final judgement.

The response of "Frankly that's tosh..." could certainly be regarded as a little knee-jerk or defensive.

Having said that, "Your QR lever wasn't nearly tight enough or at a proper angle if this happened." could quite easily be interpreted as "you don't know what you're doing" and maybe just the subtle addition of "Do you think it's possible that..." at the start might promote a more collaborative discussion amongst respected equals.

Forum court is hereby adjouned. (gavel)
Sometimes everyone "doesn't know what they are doing". If that is an insulting concept, it is best not to have a mechanics advice forum.


​​​​Instead, everyone can just learn through trial and error on their 50+mph vehicles. They might get killed, but at least their feelings will be intact.

Meanwhile, somewhere on this forum someone is being mercilessly mocked for their opinion about paint colors. But I was the rude one.
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Old 03-01-24, 02:28 PM
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Well.....I got my tracking info today so Shimano is going to ship me another one. Thanks to you all for suggesting this!
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Old 03-01-24, 02:46 PM
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Originally Posted by howaboutme
Well.....I got my tracking info today so Shimano is going to ship me another one. Thanks to you all for suggesting this!
That's great - good outcome
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Old 03-01-24, 03:24 PM
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Originally Posted by howaboutme
Well.....I got my tracking info today so Shimano is going to ship me another one. Thanks to you all for suggesting this!

What bike frame are you going to buy for it?
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Old 03-02-24, 11:25 AM
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Originally Posted by Kontact
It broke like that, because that part is made of plastic.
Good god! Has Shimano learned nothing from their Dura Ace/ Ultegra cranks episode? They are going to have another ‘thanks Shimano’ page spring up somewhere with 1000’s of pictures of broken plastic derailleurs. Shimano is seriously losing their way now with these goofy material choices.
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Old 03-02-24, 11:40 AM
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Originally Posted by icemilkcoffee
Good god! Has Shimano learned nothing from their Dura Ace/ Ultegra cranks episode? They are going to have another ‘thanks Shimano’ page spring up somewhere with 1000’s of pictures of broken plastic derailleurs. Shimano is seriously losing their way now with these goofy material choices.
Plastic for derailleurs is certainly not new - SRAM has always done it. The only black part on my silver first gen Rival RD is a plastic lower knuckle. What has changed is the price. It is one thing to have an issue that breaks the plastic on your $50 derailleur, quite another when the derailleur costs $200.

You can fix the problem by going back to metal parts, or by going to removable fasteners so you can replace damaged subcomponents. But fragile luxury sports equipment is a bridge too far.
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Old 03-19-24, 11:34 AM
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Originally Posted by howaboutme
Well.....I got my tracking info today so Shimano is going to ship me another one. Thanks to you all for suggesting this!

Hi all, first message on this forum, thanks in advance for you help.


This thread enlightened me since I had exactly the same rupture without any crash or blow on the RD.


At my bike shop they are telling me Shimano does not consider this damage under warranty since this kind of damage is not in their database.

howaboutme, could you please share any reference of the ticket/replacement you had?

Thank you in advance!


Hope this could solve my issue since it is really the same - sorry I cannot post pictures since I need min 10 posts...

Last edited by SuperKeyEvo; 03-19-24 at 11:39 AM.
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Old 03-19-24, 01:51 PM
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Originally Posted by SuperKeyEvo
Hi all, first message on this forum, thanks in advance for you help.


This thread enlightened me since I had exactly the same rupture without any crash or blow on the RD.


At my bike shop they are telling me Shimano does not consider this damage under warranty since this kind of damage is not in their database.

howaboutme, could you please share any reference of the ticket/replacement you had?

Thank you in advance!


Hope this could solve my issue since it is really the same - sorry I cannot post pictures since I need min 10 posts...
I don't have the case # anymore, sorry. I deleted everything once I got the replacement. Everything was through email. At the suggestion of the nice forum members, I submitted a request online. It doesn't provide any real space to explain exactly the problem but Shimano case officer responds to ask what the problem is. That's where I explained and provided photos. A day or two later, they asked me to send it in for inspection (on my dime) with the proof of purchase. A week later, voila! I got a new $300 product that's sitting on my floor catching dust. For me, it's a zero sum gain since I already paid for a new one.

More specific to you, I chose NOT to go through the LBS. I think you have to go direct.
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Old 03-19-24, 02:25 PM
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Originally Posted by SuperKeyEvo
Hope this could solve my issue since it is really the same - sorry I cannot post pictures since I need min 10 posts...
Pic Assist - https://www.bikeforums.net/g/picture/33084427

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Old 03-19-24, 02:29 PM
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That breakage looks pretty familiar. Wonder if this is a real thing now....and how many others are out there?
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Old 03-20-24, 09:44 AM
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Thanks a lot for posting the pic, cb400bill!

Still trying to go through my LBS where currently the bike is.
If it does not work, I will do it myself, as suggested by howaboutme.

105 Di2 was launched 1 year ago and in the last month we have 2 cases here...if there is any faulty design, Shimano cannot stand still...

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Old 04-09-24, 09:51 AM
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Hello, I know I'm late to the party, but I can chip in.
I have been fixing Di2 components for a while now, I can tell that 8 out of 10 times is down to the user error. I'm not implying this was the case for the users above.
You can visit my instagram or YouTube channel, just search for Di2_GP - I can't post links here, as I'm new :-)
Usually this is caused by cross chaining with too short chain, or on 11 speed by a bodge where people 'converting' SS to GS by swapping just a cage.
But sometimes, especially on Dura Ace where bodies are made from CF- PA and there are micro air bubbles trapped inside the piece during injection moulding.
On Ultegra 11spd body was made of GS- PA, and I have only seen this damage caused by a crash.
I woudl check the cracked part to see if there are any 'bubbles' visible voids where the part snapped.
If you have any questions, please drop me a DM on Insta or YT.

Fiannaly, sorry for a shameless plug, but I'd appreciate if you could visit my channels, and if you like what you see, please subscribe.

Thank you
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