14

I suddenly noticed a crack in my frame.

Is it practical for me to use glue to seal it off as a temporary solution?

enter image description here

Edit: Further information ...two incidents so far. Someone opened their driver side door on me and I slammed into it. That considerably weakened it. Then I fell again while turning a sharp corner, it broke it.

Update from 29th Jan 2019:

  • I went to a bike shop and they told me they could not replace it; I need to talk to the shop where I bought it from and get a replacement from them. Does it have to go this way? I would imagine this fork could be easily replaced.
  • 3
    Out of curiosity: what kind of riding are you doing on that bike? You have obviously over-stressed the fork. Or did you crash or get hit by something? What make/model of fork is it? – Argenti Apparatus Jan 27 at 13:04
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    @Criggie I noticed the kickstand, kinda wondered if the OP had been riding big drops on a hybrid :-) – Argenti Apparatus Jan 27 at 18:53
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    @DanielRHicks that is what broken cast metal looks like. For a comprehensive collection of broken things from different materials, checkout pardo.net/bike/pic/fail-001/000.html – ojs Jan 27 at 22:29
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    If it was damaged in the first accident with the car then it should have been replaced at that point, by the person who was at fault in the accident. You are incredibly lucky that the actual break didn't cause more damage to you and/or others. – Criggie Jan 28 at 6:36
  • 2
    @Criggie, you can see a clear two-stage failure process in the fracture surface. The small, smooth-textured area on the outside front corner would be the crack from the first collision. The large, jagged surface is the break from the fall. If the paint's got any sort of flexibility, you wouldn't be able to see the initial crack unless you're bending the fork, and possibly not even then. – Mark Jan 28 at 20:58
60

No.

The consequences of fork failure are likely to be severe and painful. This may only be a secondary fork crown but it's still structural. The fact that it's such a wide crack means something is already deformed and weakened. Any glue joint would be under huge stress and aluminium doesn't glue well. If this happened out on the trail it might be possible to ride back to civilisation at walking pace on a fire road, but I'd probably rather scoot the bike standing on one pedal. As your picture indicates it's indoors, you need a new fork before riding it anywhere.

I wouldn't even ride it to a bike shop.

More generally (thanks to cmaster): Never ride a bike where there's so much as a crack in a) the front axle, b) any part of the fork, including the steering tube, c) the stem, or d) the handlebar. There is zero backup for any of these parts, and failure usually means immediate loss of control and consequently unmitigated crash.

  • 11
    Fork failures will also be extremely quick, and instinctive braking at that instant will make it worse. – Criggie Jan 27 at 18:45
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    Exactly. Never ride a bike where there's so much as a crack in a) the front axle, b) any part of the fork, including the steering tube, c) the stem, or d) the handlebar. There is zero backup for any of these parts, and failure usually means immediate loss of control and consequently unmitigated crash. Don't play with your health and life like that. – cmaster Jan 27 at 20:45
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    @leftaroundabout the advantage however is that there is nothing between you and the ground - if the bike fails, you just walk away. If the front fork fails while riding, either you are flung, or you and the bike make a (possibly messy) intersection. – Baldrickk Jan 29 at 9:51
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    @leftaroundabout sure, it can still go wrong, but it's less likely to drag you down with it if you are already halfway off. – Baldrickk Jan 29 at 13:39
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    Can we add cmaster's comment to the answer, as comments are subject to deletion? – Mathieu K. Jan 29 at 15:00
47

NO!!

That's not a "crack" – it's broken in two! You need a new fork. Your current fork has completely failed. Any attempt to repair it will create a massive weak spot which will just break again. Anything going wrong around your front wheel has the possibility of throwing you over the handlebars into the path of a truck.

Furthermore, a significant piece of structural metal on your bike has broken. Unless there was a pre-existing crack, whatever did that must have applied a huge force. Check very carefully that nothing else on your bike is damaged.

  • 12
    'That's not a "crack"' - It's just a flesh wound... youtube.com/watch?v=UijhbHvxWrA – WernerCD Jan 27 at 16:39
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    The picture's not the best in the world, but it looks like there's a very substantial manufacturing defect: about half the thickness of the metal at the point of failure appears to be slag inclusions or some similar metallurgical defect. The crack itself looks like it's fatigue-related. Between the two, it wouldn't take very much force to break the fork -- all the more reason to replace it, but the rest of the bicycle is probably in fine shape. – Mark Jan 27 at 22:51
  • @Mark I'm not convinced. Admittedly it's almost 40 years since I studied metallurgy, but I can't see any obvious defects. (Note: I think we are all agreed on the first para of the answer, and it can't hurt to follow the advice in the third.) – Martin Bonner Jan 28 at 13:54
8

As others have said the fork is trash and the bike should not be ridden.

Given the nature of the incidents that led to the fork breaking (described in comments), the rest of the bike should be checked for damage, especially the front wheel and headset area of the frame.

Update:

Re: fork replacement: any decent bike store with a competent repair shop should be able to order and install an replacement equivalent fork, even if it is of a different brand. If the fork is branded the same as the rest of the bike, that may be why the bike store told you to go to the store you bought the bike for. Find a different store that is more willing to help.

protected by Community Jan 31 at 20:12

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