Anyone seen a mech break like this?

steve_sordy

steve_sordy

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I had an off and bent one of the mech arm plates. The outer plate was bent outwards. The jockey wheel is end-on in the picture and parallel to the inner plate. You can see the outer plate flaring (and that is after @myapes had a go at straightening it. The shifting was still fine though, so we pressed on.

Mech 2.jpg


About 200 yards further on, I got one of those young pine tree branches stuck in the mech. It was about half an inch thick and very bendy. They are difficult to break, but cut easily. There was a horrible graunching noise and my transmission went hard, so I stopped pedalling straight away. I looked down and half the mech was hanging from the chain! The mech had snapped just below the clutch body. The mech hanger was unbent (as far as we could tell).
In the picture below, the mech arm holding both jockey wheels is upside down. You can see the clutch body. The fracture passed through the centreline of that silvery bit that is a metal plug that a screw goes into to secure the clutch housing (1of 3). There is a gasket that seals the clutch and that is exposed by the fracture.
Mech 1.jpg


Here is the main body of the mech, still attached to the bike. The fracture runs along the bottom edge of the mech that you can see, just below the hinge.
Mech 3.jpg
 
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Well
yes l guess, if you are cranking the pedals on an ebike and the transmission stalls due to a tree branch stuck in the mechanism, the motor will deliver maximum torque because it will think you hit a rock step or similar.

So it will likely smash the rear mech up good and proper, as has happened to yours.
 
lightning said:
Well
yes l guess, if you are cranking the pedals on an ebike and the transmission stalls due to a tree branch stuck in the mechanism, the motor will deliver maximum torque because it will think you hit a rock step or similar.

So it will likely smash the rear mech up good and proper, as has happened to yours.
Click to expand...
Fortunately, I was going dead slow at the time (sharp right hairpin downhill), otherwise I dread to think what else might have got damaged.
 
I have just discovered that the lower jockey wheel's easy movement has been constrained by the bent side plate. It will turn but it is quite stiff. Whether that happened after the first crash, was caused by @myapes attempt to straighten it, or the second crash I now have no idea. :unsure:
 
Well, you've turned the rear mech into a piece of modern art, so you could try selling it to the Tate Art Gallery.
After all, they once bought a pile of bricks for around £50,000

Or mount it on a piece of wood and give it to your girlfriend for Christmas
 
If you’re binning mech, can I have the jockey wheels please?
 
Doomanic said:
If you’re binning mech, can I have the jockey wheels please?
Click to expand...
Sorry, I will be keeping both bits of the mech for spares. The mech has hardly done any miles at all and I'm sure to knacker the next mech too, so I might need the bits.
 
I did that the other day too. Bloody stick got me. I think It was one that I had cut shortly before doing some trail maintenance, so it was revenge of the stick!
 
Hopefully we can get another ride sorted soon so I can attempt the big hill :D
 
I’m going to buy a spare I think, just in case and knowing my luck I’ll break it next ride.
 
Damn, after breaking my mech the other day, I also damaged my cassette. Broke a tooth of my largest cog, and second gear skips, so, I ordered a new one from Holand. Unfortunately, I made the mistake of ordering the new one with 10-52T which is incompatible with the Sram NX derailleur. So, I have to send it back to get the 10-50T on which is extremely difficult to find.... and expensive.
 
snapped one today :)

riding on a pretty abandoned forest service road, a branch leaped out and threw itself at the moving parts, I suspect part of it caught on the frame and then ripped the mech out. I broke the chain and picked a middle gear (which was horrible) and rode out. Called in the store in the village who handed me a new mech without any drama.

20210806-IMG_5813.jpg
 
steve_sordy said:
Now that is what I call thoroughly trashed. :eek:
Click to expand...

it's on the desk next to me, looking at it seems to show something probably got caught in the guide pulley and then twisted that 180º and then it snapped near the mount. Not surprising that it snapped when you see the force that must have been on it.

I think it'll take a couple of days to get a like-for-like, the LBS offered one that won't quite work.
 
Make sure you check the hanger as well. If it's bent it'll make setting the mech up "interesting"...

...ask me how I know... :mad:
 
steve_sordy said:
I had an off and bent one of the mech arm plates. The outer plate was bent outwards. The jockey wheel is end-on in the picture and parallel to the inner plate. You can see the outer plate flaring (and that is after @myapes had a go at straightening it. The shifting was still fine though, so we pressed on.

View attachment 67996

About 200 yards further on, I got one of those young pine tree branches stuck in the mech. It was about half an inch thick and very bendy. They are difficult to break, but cut easily. There was a horrible graunching noise and my transmission went hard, so I stopped pedalling straight away. I looked down and half the mech was hanging from the chain! The mech had snapped just below the clutch body. The mech hanger was unbent (as far as we could tell).
In the picture below, the mech arm holding both jockey wheels is upside down. You can see the clutch body. The fracture passed through the centreline of that silvery bit that is a metal plug that a screw goes into to secure the clutch housing (1of 3). There is a gasket that seals the clutch and that is exposed by the fracture.
View attachment 67997

Here is the main body of the mech, still attached to the bike. The fracture runs along the bottom edge of the mech that you can see, just below the hinge.
View attachment 67998
Click to expand...
High Rock Ruti
I hope you listen?

Put it in a box and send it to Shimano they'll send back a new derailleur. I don't include a note, I don't fill out the online warranty request, "nothing" except a return address.

I've gotten 4 four brand new derailleur's this way. I'm so impatient I usually buy a new one and so I have a spare which of course allows me to send the next broken part in for exchange.

Don't feel bad. I break derailleur's at least once a year. Shimano is a fantastic company that stands behind what they sell, drive trains are warrantied for two years, I recently got two shifters replaced for free. I hate having a broken ebike just got back from a five week vacation, road everyday brought 2 bikes needed both. 2022 turbo levo pro motor failed with about 500 miles on it, that Brose motor is a POS, at least the clutches are.
Specialized is send a new motor another stand up company.

Warm Regards Ruti
 
High Rock Ruti said:
High Rock Ruti
I hope you listen?

Put it in a box and send it to Shimano they'll send back a new derailleur. I don't include a note, I don't fill out the online warranty request, "nothing" except a return address.

I've gotten 4 four brand new derailleur's this way. I'm so impatient I usually buy a new one and so I have a spare which of course allows me to send the next broken part in for exchange.

Don't feel bad. I break derailleur's at least once a year. Shimano is a fantastic company that stands behind what they sell, drive trains are warrantied for two years, I recently got two shifters replaced for free. I hate having a broken ebike just got back from a five week vacation, road everyday brought 2 bikes needed both. 2022 turbo levo pro motor failed with about 500 miles on it, that Brose motor is a POS, at least the clutches are.
Specialized is send a new motor another stand up company.

Warm Regards Ruti
Click to expand...
Great idea. :)
I had not considered it a warranty claim. But it's worth a try. It will cost little but my time and a bit of postage.
 
I had the exact same breakage this morning - however I was on a slow climb up a fire road - there was no stick or undergrowth to foil the mech - it just went crunch and was like that - I think the mech breaks as that part seems to be plastic or composite - I have a sacrificial bolt on the hangar and that was intact .
I am definitely taking it up with Madison / Shimano as I think it is a material failure
. The frames holding the pulleys are also very flimsy these days
 
Mark45acp said:
I had the exact same breakage this morning - however I was on a slow climb up a fire road - there was no stick or undergrowth to foil the mech - it just went crunch and was like that - I think the mech breaks as that part seems to be plastic or composite - I have a sacrificial bolt on the hangar and that was intact .
I am definitely taking it up with Madison / Shimano as I think it is a material failure
. The frames holding the pulleys are also very flimsy these days
Click to expand...
Well that is three identical failures just on this thread in a few days. Me, you and @Peterg
 
High Rock Ruti said:
High Rock Ruti
I hope you listen?

Put it in a box and send it to Shimano they'll send back a new derailleur. I don't include a note, I don't fill out the online warranty request, "nothing" except a return address.

I've gotten 4 four brand new derailleur's this way. I'm so impatient I usually buy a new one and so I have a spare which of course allows me to send the next broken part in for exchange.

Don't feel bad. I break derailleur's at least once a year. Shimano is a fantastic company that stands behind what they sell, drive trains are warrantied for two years, I recently got two shifters replaced for free. I hate having a broken ebike just got back from a five week vacation, road everyday brought 2 bikes needed both. 2022 turbo levo pro motor failed with about 500 miles on it, that Brose motor is a POS, at least the clutches are.
Specialized is send a new motor another stand up company.

Warm Regards Ruti
Click to expand...
Good luck with that if you are in the UK , can’t even find an address, just take it back to the supplier, ont tinternet . Guess what …. They don’t want to know .
 
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