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I screwed up :( Background leading to my foolishness: I've been straining my bike quite a bit with hills and inclimate weather, and I haven't been able to find my maintenance kit since I've moved, so in my busyness I've let myself push around on a squeaky rusting chain. I realize I may be learning an expensive lesson now.

Today I kicked off and start pedaling, finding my chain was jammed up and not moving smoothly through a full rotation. That has happened before with a poorly oiled chain and I've pushed or shifted my way back into relatively-smooth operation. Well I pushed and it was stuck, not moving forward at all. Should've got off there but instead I pedaled backward a little, shifted and pushed, and it moved a little. That inspired me to push harder, and in my haste I pushed recklessly hard to pedal forward. Well, it stayed stuck and felt pretty wonky at that point, so I calmed down my haste and got off to check what's wrong. I found the back wheel had tilt/camber to it and the derailleur was bent out of alignment - I was definitely not getting anywhere quick anymore!

I'll bring this to a local bikeshop ASAP to get repaired. Seeing what appears to be a weld severed, I'm not sure if this is a costly repair or a major overhaul I'm looking at. How bad are the damages, can you identify what specifically appears damaged and in need of repair? Is the frame and hub okay to keep and just needs a new derailleur?

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From a different angle:

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Rear wheel appears normal to me, no clear damage on axle, spokes, wheel frame or anything. I think the connection point for the rear wheel to the frame is what got busted in some way from my pushing, which led to the derailleur getting bent and the wheel off-camber.

  • I can't tell where you see a broken weld; maybe you could mark it in the pictures? It's also hard to tell the from the pictures if the wheel is warped, or if the frame is bent. – DavidW Oct 25 '19 at 14:30
  • @DavidW edited post to highlight that break point in 3rd image (not sure if scuffs are sign of a weld or just friction from parts that were pinched together by the rear-wheel detach screw), and to clarify that rear wheel appears normal to me. – cr0 Oct 25 '19 at 14:38
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    All rear derailleurs bolt on to an extension called a derailleur hangar. Most frames have replaceable hangars that are bolted to the frame. I can't tell from the picture, but it looks like the RD hangar actually is still attached to the frame. Is this so? Whatever the case, the hangar can be replaced. The RD looks dead, which you knew. I can see a scratch on your frame's dropout, but that looks like scratches on an alloy frame, and that should not doom the frame. – Weiwen Ng Oct 25 '19 at 14:45
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    The bent piece of metal is actual 1 of the pieces of the derailleur cage. It sheared off of the idler bolt, which is just beside the rotor in your bottom image. – DavidW Oct 25 '19 at 14:58
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    I upvoted this solely for the fact that GOOD pictures were included to start, and then clarified after. Well Done. – Deleted User Oct 25 '19 at 16:07
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Updated based on your edits and comments.

The severed piece of metal circled in the 3rd image is one of the cage plates, and was originally attached to the lower (idler) pulley bolt. Beyond replacing the derailleur, there is no additional damage there. It really does appear that you may only need to replace your derailleur (and chain).

Other items to check out, at least to verify that nothing else is broken:

  1. If you can spin the wheel and it rotates cleanly on the axle and is straight and the spokes are unbroken, straight, and under even tension then the wheel is good. (If some of the spokes are deeply scored you may want to replace them anyway.)
  2. If the freewheel spins cleanly, and there are no bent teeth or wobble then it is okay. (Though if you're replacing the chain it may need replacing anyway depending on wear.) Based on the way the derailleur bent it's not likely it damaged the freewheel, but it's still worth checking.
  3. If the frame itself is not bent (the distance between the dropouts hasn't changed, they are still evenly vertical and level with one another, and the stays are all straight) then it's fine. (If it's a steel bike then a small amount of bending is survivable, but if it's aluminium it's trash.)
  4. Obviously the derailleur is trash, but the derailleur hanger might be too. (It's hard to tell from looking at the back side like this.) You'll probably want the shop to make sure it's not twisted, which would cause the derailleur to mis-align.
  5. You need a new chain, no question, since it sounds like a jammed link is part of the sequence that caused this.
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    Thanks for the details on how to diagnose more specifically. When I'm back with my bike I'll give those checks a go to get a better idea what's wrong then bring it in for repair. It seems like the main game changer is if the distance between dropouts changed or not. I'll leave the question open for a while to follow SE etiquette but this is the answer I was looking for otherwise. Thanks – cr0 Oct 25 '19 at 14:58
  • Ended up replacing the derailleur and chain, and with the new chain a new rear gear cassette was needed as the other was far more worn than the fresh new chain. – cr0 Oct 29 '19 at 14:53
  • @cr0 Yeah, that's often the way it goes. I once tried riding for a couple of days with a new chain on the old cassette (emergency chain replacement, but no cassette in stock) and it was brutal. – DavidW Oct 29 '19 at 15:01
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How bad are the damages, can you identify what specifically appears damaged and in need of repair? Is the frame and hub okay to keep and just needs a new derailleur?

From what I can see it's a derailleur replacement and possibly a chain replacement - depending on how twisted the links are.

In the larger circle there are scrapes on the drop out but I can't see an actual crack.
The smaller circle looks like the derailleur hanger - which is replaceable with the derailleur.

I don't see any hub issues.

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    I would spend a bit of time inspecting the spokes for damage and replace any that are broken or have deep gouges (as it will resulting in a fatigue fracture in the future). - How deep before replacing, for me not very, spokes are cheap compared to a long walk home. – mattnz Oct 25 '19 at 18:57
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    Honestly, after a chain has been abused that badly, it probably needs replacing, regardless of whether it's visibly bent. – David Richerby Oct 27 '19 at 9:25
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The deraillier hanger(also called a frame saver)..did its job..its probably bent..and it looks like a mech, chain(cassette if worn or damaged) and inspection on hub and spokes.. and replacing as neccisary.. so in short I see no frame damage..just the breakable(weak links) did there jobs just fine..if you haven't already buy a deraillier hanger alignment tool(I own the new wolftooth hat tool and it's super easy and simple to get it setup right)..I've found my hanger bent after even minor knocks..and I would also recommend carrying a spare one as if it does its job right it's likely to break off entirely..then you can get running after an accident(doesn't take a lot on yo break them..)

The bolts for the hanger are just above the hanger itself .the small recessed Allen bolts on the outside of the frame leg and threading into the hanger hold it on ..just unbolt those to replace it(its likely compromised now it's taken that much strain..)..I would recommend replacing it..it only costs £5-20 and are readily available..if your shop replaces it ask them to but you a spare too so you have it(plus the bolts to attach it..)

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