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Alu frame bent, is it safe to use?
#1
Hi! I got a large truck going over my rear wheel, completely twisting it. The pressure was so high, that the left pedal exploded (see pic).

I hoped the frame is OK, but it seems it's about .5-1cm bent to the left side. I think if I get a new rear wheel, I can still ride this thing. Question is, is it still safe to use?

Bike model is Centurion CrossLine 100 http://www.centurion.de/en_int/bikes/2014/81/Urban+%26+Country/Cross+Line+100

It's not an expensive bike, price of repairs vs getting a new similar is about 30-50% difference.
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#2
NO, it is NOT safe. Aluminum used in bike frames (6000 and 7000 series alloys) will crack when bent. Crack will grow.
Nigel
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#3
(06-14-2014, 10:57 AM)nfmisso Wrote:  NO, it is NOT safe. Aluminum used in bike frames (6000 and 7000 series alloys) will crack when bent. Crack will grow.

Thanks! So I should inspect the frame for cracks and see if it's big or not, or is it a complete show stopper and I have to get a new bike? What if I can't find a crack? Is it there in 100% of the cases? It's not like it's all twisted, w/o measuring the sides you won't even notice it's bent (I didn't)
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#4
You should inspect the frame or have someone knowledgeable do so. No one here can give you any kind of reliable answer. It depends on where it bent, how it bent, how you ride, how big you are, etc. etc. etc. Nfmisso is right about the nature of aluminum. But plenty of people have ridden slightly bent alu frames for years without problems.

I wonder if you'll ever get the rear brake disk aligned in the caliper if the rear triangle is tweaked.
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#5
Thanks DaveM, haven't thought about that. I guess the only way to find out is to try fitting a new wheel and see. This one doesn't go all the way around... I will check if there are any cracks, and If i find a single one, I will just get a new bike instead.

Btw, if you weld the crack, is it going to solve the problem, or is it going to grow bigger anyway? Did anybody try that? My style of riding often includes jumping from the sidewalk to the street and vice versa, so I don't want to risk it.
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#6
yes, cracks can be repaired. take your wheel off and bang it on the ground to reshape enough to spin in your frame. That will help let you know about your brake or not. assuming your rotor did not get hurt. take the tire off if you have to, that will give you extra room. if your tire does not hold air, bang it in the yard to reshape
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
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#7
one method to tell if it is cracked, it to go along the tubes with drum stick or wood dowel or similar, and gently tap on the frame, it should ring softly, a section with a crack will kinda thud.
Nigel
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#8
Gotcha! Thanks for your advice guys!
  Reply
#9
So the only damaged area I could spot is where the wheel struck the frame, and it looks more like a scratch rather than a crack. I got a new wheel and the bike is as good as new. Thanks everyone, phew.
  Reply
#10
glad to hear that your bike is back Smile
Nigel
  Reply


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