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Old 09-06-09, 04:43 PM   #1
larrynem
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dented top post and down post

I ran into the back of a parked car going about 12 miles per hour. Luckily I survive more or less intact. My bike (C-dale Synapse) appeared unharmed. Two months and 1200 miles later I noticed dimples about the size of a pinky finger on the bottom side of both the top post and the down post, about two inches from the front connections. The rest of the frame appears to be unharmed.

Question: How risky is it to continue to ride my bike? Am I tempting fate?
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Old 09-06-09, 04:46 PM   #2
jtarver
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You're tempting fate.
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Old 09-06-09, 04:57 PM   #3
wrk101
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You're tempting fate.
+1 Retire the frame.
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Old 09-06-09, 05:17 PM   #4
JohnDThompson 
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I ran into the back of a parked car going about 12 miles per hour. Luckily I survive more or less intact. My bike (C-dale Synapse) appeared unharmed. Two months and 1200 miles later I noticed dimples about the size of a pinky finger on the bottom side of both the top post and the down post, about two inches from the front connections. The rest of the frame appears to be unharmed.

Question: How risky is it to continue to ride my bike? Am I tempting fate?
With a steel frame you could continue to ride it, albeit with handling changes due to the change in front-end geometry, but since you have an aluminum frame you're already tempting fate. Retire the frame.
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Old 09-06-09, 08:29 PM   #5
Panthers007
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Agreed. Remember Murphy's Law? You'd be doing 40 mph down a steep hill when it tears apart. The good news: There would be a cemetery at the bottom of the hill.

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Old 09-06-09, 08:48 PM   #6
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This pic is useless without pics...

You're describing buckling of the tubes caused by the crash. Aluminum is very unforgiving with fatigue compared with steel or Ti. It can simply snap when bent too much.

It's better that the dimples are on the bottom of the tube rather than the top. If they were on the top, I'd guess the frame is going to go very soon. On the bottom it's from the original crash, and you probably didn't notice.

It's not like it's going to assplode into a million pieces, but it's hard to say how much warning it will give when it goes. It might never go. Could be that you hear a crack and the down tube splits halfway. Could be you hear a crack and both tubes split almost instantly. Aluminum is funny that way. The high strength alloys don't like to bend.

Last edited by twentysixtwo; 09-06-09 at 08:51 PM.
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Old 09-06-09, 10:27 PM   #7
Panthers007
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Semantics. Aluminum has very little tolerance to bends and dimples. It WILL go - if you ride it. And in the worst way there is. If ol' Murphy knows his a** from his elbow. Retire the frame - yesterday.
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