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My girlfriend's bicycle was vandalized by a neighbour. It seems like they banged it with a hammer or something right in the middle of the frame. Is this still safe to use?

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    That looks like a thin-walled aluminum frame. Try this: sit down in a chair. Take an empty aluminum soda can and put it upright on the floor in front of you. Take one of your feet, place it on top of the can and slowly put a decent amount of weight on the can - not enough to crush it, but a good amount of weight. Now carefully lean over, and without removing any of the pressure from your foot on the can, tap the side of the can with your finger. That can will collapse almost immediately if you do it right. Tubes get a lot of their strength from the uniform shape - dents ruin that. – Andrew Henle Jan 17 at 16:45
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    I thought Condor Fratello(s) were steel so edit the question with frame material - most answers are assuming aluminium at this point. I expect the answer will still be to not ride the bike but you might get input on how to get it fixed well. It’s certainly a quality frame worth considering fixing (and getting neighbour to foot the bill). – Swifty Jan 17 at 16:55
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    If it's steel it's probably safe to ride in the short term, but the bend is extreme enough that it will tend to fatigue and crack over the long term (ie, after hundreds if not thousands of miles). If it does crack the failure is not apt to be catastrophic -- the crack will visible before the frame fails completely. Aluminum, on the other hand, is apt to fail catastrophically after only a few hours use. – Daniel R Hicks Jan 17 at 21:56
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    That doesn't look like it's been hit by a hammer, to me. Looks much more like a vehicle has been driven into it or something like that. You'd need to swing hard with a very heavy hammer to do that sort of damage. You'd also have to hit it just right as an off-centre blow would likely be deflected by the curve of the tube. It doesn't look like there have been multiple strikes and I think somebody would have to be pretty lucky to make that hit as a first attempt. – David Richerby Jan 18 at 10:56
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    @DavidRicherby I agree with your assessment and based on it, I'd say it looks more like an accident than vandalism (of course you can drive a vehicle into it on purpose, but I'd think it's unlikely they did so and then decided to stop after this relatively minor damage). While the distinction doesn't really help, it does fit nicely with Hanlon's Razor: "Never attribute to malice that which is adequately explained by stupidity." – Jasper Jan 18 at 14:02
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Unfortunately I think that level of damage with a big dent and buckled top tube will make the bike dangerous to ride. There's a chance that when a big bump or pothole is hit the top tube will fold and dump the rider face first into the road.

Additionally, the head tube probably is not aligned with the seat tube anymore, which means the wheels are misaligned which will negatively affect steering.

  • @psmears fixed. BTW, feel free to edit posts for spelling, punctuation, typos etc. – Argenti Apparatus Jan 17 at 23:33
  • Thanks! Yes, I usually do edit, but I can't submit an edit that changes less than six characters, and I couldn't see anything else to improve in your post :) – psmears Jan 17 at 23:34
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That frame is definitely not safe to ride anymore. While some steel frames can handle dents pretty well, that is some major damage in what seems to me an aluminium frame. The top tube seems both dented and bent, which likely has affected the steering of the bicycle and also introduces risk of the frame bending inwards under stress.

I recommend you don't ride that anymore, start looking for a replacement and see if you can get the person responsible for that to fund it.

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Sorry for that act of vandalism that happened to you. But I'd refrain from using this bicycle any longer. You'd have problems riding it in a straight line because the wheels are certainly misaligned now which could even cause more uncertain behaviour at speed. The other danger could reside in the sudden failure of the compromised top tube of the frame.

The only thing you could do, apart from filing a complaint with the police would be to take the bike apart and re-use or sell all the undamaged parts.

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Not safe, due to buckling

That top part of the frame has buckled. As such it has — and I am not exaggerating now — less than one tenth of its design strength. That bike will fold in on itself if you try to use it.

Hence, sorry, but that frame is busted for good.

  • The frame is steel and it is very likely that a new tube can be welded there. – Vladimir F Jan 18 at 9:12
  • @VladimirF It can be any metal, aluminium, steel or - most likely - an alloy. Welding aluminium alloys is difficult at best. A used replacement frame can be found for less than 100 USD / 70 EUR equivalent. – MichaelK Jan 18 at 9:23
  • In the comments below the question you will find out it is steel. – Vladimir F Jan 18 at 9:28

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