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Big hole in top tube of new bike (Pics attached) aluminum repair with carbon fiber

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Big hole in top tube of new bike (Pics attached) aluminum repair with carbon fiber

Old 11-24-20, 11:18 PM
  #76  
Duragrouch
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Originally Posted by Yellowlab View Post
I understand the thread at this point is large enough to deter people from wanting to read the whole thing, I probably wouldn't have so I don't blame you, but.......had you read the rest of the thread before posting here you'd understand that your sentiment is akin to
You're right, I had not read the whole thread. Sorry to be repetitively redundant.
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Old 11-25-20, 06:15 PM
  #77  
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You need to pay more attention to the swing on your machine.
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Old 11-26-20, 12:48 PM
  #78  
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Originally Posted by stevoo View Post
I will pass on making comments on the repair as I think that has been covered well enough.
However, it is Impressive that after sustaining that kind of damage the frame is still straight and rides well?
Not sure if the OP performed any frame alignment checks but I don't recall reading in the thread that they noticed any changes in ride or handling. Amazing.
I once hit a bike top tube w a car and it was bent and not rideable.
I found a way to measure if or how much the top tube is bent. I simply took a string and looped it around the seat post and head tube above the top tube. It seems the top tube is in fact ever so slightly bowed toward the right side of the bike (opposite side that was hit which makes sense) but it was hard to capture in the pics. (Also, I think this may be deceiving, more on that down below) It was even kind of hard to tell in person but it is there. You can most easily spot it when you slide the string down the top tube and as both sides of the string move down, the right side makes contact with the top tube and is pushed out slightly more than the other side. I think it's minor enough, and the bike rides perfectly well that it will probably be inconsequential for the future of riding it but also........

The part I think is deceiving is that the second treatment of carbon fiber wasn't a long strip that got wrapped around three times. It was three seperate sheets that each got wrapped around once and the area on the side of the bike that appears to be slightly bowed out is exactly where those three layers all overlapped eachother so there was definitely more material on that side that I may have just not sanded down enough to match the other side.

Regardless, here are a few of the pics.

Setup:


See the the right side of the top tube (left side in the pic) slightly peeks out under the string a bit more.


Top down:

Last edited by Yellowlab; 11-26-20 at 02:33 PM.
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Old 11-29-20, 07:15 PM
  #79  
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Yellowlab,

Regarding testing: The greatest stress on the top tube is a) in torsion while climbing with hard opposite pull on the handlbars, and b) vertical bending loads into the frame from a pothole/curb/jump at high speed, which would load the top tube in compression, and it has sufficient "slenderness ratio" (actual engineering term) to buckle. And further, buckling failure is a function of stiffness, not strength. Failure (a) will probably give warning signs in terms of inspection, you'll see signs of delamination. Failure (b), unfortunately, will not; Buckling failures are by their nature "catastrophic" (another engineering term), which means the start of failure weakens the tube which then makes it proceed further to failure. The same load on the tube in tension will do no such thing, it's much stronger in tension. This is just FYI, but I think you'll be OK. Clearcoat is smart. Plus it looks cool.
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