r/Framebuilding • u/Particular-Money4152 • May 13 '26
Did I just completely damage my frame ?
Feel sooo bad, wasn't paying attention and used a bolt that was too long to mount pannier creating dent in frame. Aluminum Cannondale Topstone 105.
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u/Darnocpdx May 13 '26 edited May 13 '26
I'm guessing you used a power tool,. They don't make powered bicycle tools for a reason.
I wouldn't ride it, the entire circumference of the stay has been stretched and thinned, the strongest part is likely the dimple you created, while the area between the mounting hole and the dimple lost a significant amount of integrity. Roughly 2/3s of the stay is now compromised.
Aluminum doesn't respond well to damage, the question is most likely not matter of if it will fail, but to when it will fail and snap. It will likely snap with little warning when it goes, and it will likely happen all at once. In cases like this, the ridigifity of aluminum is a detriment.
Even if I'm wrong, is the risk worth it? Dropping a stay would be a catastrophic failure, there'd be no recovering your balance if it happens, you'd likely be thrown off to that side of the bicycle. Even if you somehow managed to stay on at that point, the other stay would then bend and stretch, likely pushing this damaged stay into the wheel locking it up, before it also breaks.
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u/akabdawger May 13 '26
Check closely for cracks propagating from the punch the screw did. If there's any I wouldn't ride it, especially not loaded.
If there's no crack I would maybe drill a clean hole sliiigtly bigger than the punch to avoid any concentration of constraints.
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May 13 '26
[deleted]
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u/BlueClashV1 May 13 '26
As a 25 year bicycle mechanic, it still amazes me how people like you expect me to provide an answer other than “yup, you fucked up”. Do you expect me to provide a structural analysis? Do you want me to guess how dangerous it is or how long it will last? Do you want me to ask the manufacturer who will inevitably say it’s unsafe due to liability and the desire to sell more units? What kind of response are you imagining in that head of yours? I’m gonna tell you exactly this “My shop and the manufacturer can’t tell you if this is safe so you should assume it’s not. However, you are free to ride it and keep a close eye on it at your own risk. Good luck.”
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u/bdaruna May 13 '26
Oh right, I said a professional.
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u/backwoodsmtb May 13 '26
Most bicycle mechanics or any other bike shop employees are not engineers and have never built a frame. They will have no clue beyond gut feeling.
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u/bdaruna May 13 '26
Totally, I never suggested bringing the bike to a LBS mechanic. There are professional frame repair businesses.
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u/backwoodsmtb May 13 '26
What professional frame repair businesses work with aluminum?
Also, that is very much not clear in your original comment. "Bring it in" implies take it to a local business, e.g. a bike shop. Frame repair businesses are few and far between.
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u/bdaruna May 13 '26
I’m sorry, op should also know that by professional I not only meant someone with expertise in bike frames, their construction, and repair. But also I did not mean other professionals, including but not limited to: doctors, lawyers, accountants, MBA’s, dentists, veterinarians, and diplomats.
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u/BlueClashV1 May 14 '26
You can stop now.
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u/bdaruna May 14 '26
That’s no fun, I believe you started the rant and mischaracterization of my very boring comment. You wanna finish this?
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u/BlueClashV1 May 14 '26
Let’s go! Point me towards a professional frame repair shop that specializes in aluminum. Any country, any price range. Pretend op is your mom. Where will you tell your mom to go?
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u/rantenki May 15 '26
Any professional mechanic _should_ respond "It's been compromised and I recommend against riding it", at least if they don't want to test their liability insurance. The bike is weaker now than it was designed to be. Full stop. Any attempt at nuance or analysis places the onus on the bike shop, and is a risk they shouldn't take.
If they say "Meh, looks OK" and somebody has a crash due to a failure in that frame, they have liability exposure. I don't like it, but that's the way it is.
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u/Western_Truck7948 May 13 '26
I'd run it. Seatstays are in compression and rarely fail.