Carbon Seat Tube: Scratch or Crack ???

[DHallerman]

Hi,

There's a "line" on a carbon seat tube, and I need your help to determine if the line is just a scratch or a crack.

The back story: I'm building up a Seven Odonata that I bought last year from another member of this Forum. This is the steel and carbon Odonata, with the seat tube being carbon.

And as I examine the frame more closely than before, I see a thin, straight line about 2 inches long running vertically on the carbon seat tube. This line is on the right side, down where the front derailleur clamp will go on top of metal shims supplied by Seven.

The line is slighly indented. If I run my thumbnail along it, the nail goes in the line ever-so-slightly.

And, being new to carbon bikes -- just steel and titanium up to now -- it's not 100% clear to me if this line is a scratch or a crack.

* How might I be able to tell for sure if this line will get bigger and fail suddenly -- because it's a crack?

* Or nothing to worry about, because it's just a fine scratch, likely caused by the earlier install of the FD clamp on top of the metal shims?

Your thoughts?

See Update Post #19 Below

Dave, who thinks the new year is a fine time to build up a frame or two for the springtime that's bound to come

[Peter P.]

Photos, please. Use the Macro setting for focusing.

To test crack, you could tap the area with a coin and see if it sounds different than the rest of the tube.

You could plug the bottom of the seat tube and fill the seat tube with water or alcohol and see if it weeps through the crack.

[DHallerman]

Photos, please. Use the Macro setting for focusing.

To test crack, you could tap the area with a coin and see if it sounds different than the rest of the tube.

You could plug the bottom of the seat tube and fill the seat tube with water or alcohol and see if it weeps through the crack.

Of course, photograph. Hard to take, but here it is, in the center of the red rectangle:

http://i111.photobucket.com/albums/n142/sunwarrior23/odonata_scratch.jpg

Also, I tried tapping the area with a coin, and it sounds the same up and down the seat tube, on the line and above and below it.

Does this help you see it now? I can try some more tomorrow, in daylight.

Thanks,

Dave, who has a vivid imagination and can picture riding a bike when the seat tube breaks catastrophically

[Pete Serotta]

Talk to Paul Levine at Signature Cycle. He is also a SEVEN dealer and I think he still has a studio in Central Valley (as well as NYC and Conn). Great guy to deal with and very knowledgeable.


Tell him that Pete and Dave are thirsty for some RED!!!!

[false_Aest]

Send it to me.

I'll test it for you.

Only charge you $150 because youre a forum member.

If it's cracked I'll only charge you an extra $50 to dispose of the frame in an environmentally friendly way. Because you're a forum member.

Trust me, you'll be hard pressed to find another forumite with as much experience with crack.

[Pete Serotta]

:confused: does it come under the "carbon cap">???

Send it to me.

I'll test it for you.

Only charge you $150 because youre a forum member.

If it's cracked I'll only charge you an extra $50 to dispose of the frame in an environmentally friendly way. Because you're a forum member.

Trust me, you'll be hard pressed to find another forumite with as much experience with crack.

[jpw]

Take the bike into a totally dark room with the seat post out. Then drop a mini torch down the tube to the 'crack' on a string and block the end of the tube with a sock or something similar. Can you see any light through the 'crack'?

Photons are smaller than water molecules.

[toaster]

I thought it read "Carbon Seat Tube: Scratch yer Crack???"

I already do that too much, trying to stop that bad habit.

[sokyroadie]

Take the bike into a totally dark room with the seat post out. Then drop a mini torch down the tube to the 'crack' on a string and block the end of the tube with a sock or something similar. Can you see any light through the 'crack'?

Photons are smaller than water molecules.


I hope you meant:
'light" in lieu of "torch"
If he uses a torch, I don't think he will have to worry about the frame one way or another :D

JB

[dave thompson]

I hope you meant:
'light" in lieu of "torch"
If he uses a torch, I don't think he will have to worry about the frame one way or another :D

JB
Torch: "olde English" for flashlight.

[rpettet]

I have an Odonata and was told by Seven that some people overtighten the front der. clamp which can cause a crack.

[Point Grey]

Yup, looks like a crack. give Sevencycles a call as they should be able to replace

[DHallerman]

Talk to Paul Levine at Signature Cycle. He is also a SEVEN dealer and I think he still has a studio in Central Valley (as well as NYC and Conn). Great guy to deal with and very knowledgeable.

Ah yes, excellent idea.

In fact, my wife went to Paul at his Central Valley studio (about 30 minutes from our place) last June for a fitting.

That was much fun to watch...the details he went through and all.

[DHallerman]

Take the bike into a totally dark room with the seat post out. Then drop a mini torch down the tube to the 'crack' on a string and block the end of the tube with a sock or something similar. Can you see any light through the 'crack'?

Photons are smaller than water molecules.

Great idea! I tried it just a few minutes ago, and no light at all comes through the seat tube.

Of course, that only rules out a crack all the way through the tube, right?

I mean, a partial crack would still be a crack -- something that could and likely would grow -- even if not fully through the tube.

[DHallerman]

Yup, looks like a crack. give Sevencycles a call as they should be able to replace

Well, that might not work for me.

As my OP mentioned, I am not the first owner. And as the Seven site describes their policy: "the warranty is valid to the original retail purchaser only."

So, I'd have to see if the cost of a repair is worth it, relative to the cost of the frame.

Dave, who surely doesn't need any more bikes but if he did perhaps he would be best to stick with steel and titanium and not this carbon stuff that is harder to judge when bought used

[572cv]

Seven makes bomber frames. What is the tube finished with? clearcoat or something? I had a bike which was painted, had similar cracks in the finish paint. Sent it back to the builder ( it needed repainting anyway) who very carefully examined the frame, said it was very good, and repainted it. My sense is that coefficent of expansion differentials in a finish material such as paint or clearcoat and the carbon frame will lead to longitudinal cracks in the finish. In such a case, the appearance is degraded, but not the structure. I may be wrong about the theory, but it meshes with my experience.

[Peter P.]

I mused about this problem during the day and came up with another possible solution, which I think might be a great help to anyone with a carbon frame that wants to examine a potential crack.

Buy some light colored nail polish or model paint and brush a stroke over the suspected crack. Should the crack be "active" and continue to propogate, it'll crack the nail polish/model paint, too.

If you see no change after a few week's ride, you can remove the paint.

[jpw]

Yes, "torch" = "flash light". That's ye olde English Anglo Saxon speak. Not too many of us left over in Europe any more.

[DHallerman]

So I sent a somewhat better quality picture of the "line" on the carbon tube to the service manager at Seven Cycles.

And here's his response:

Sorry for the bad news, but that line is the beginning of a crack. It looks like the front derailleur was over tightened, just like you thought, and pressed into the carbon. The carbon fibers may not have splintered yet, but in time they will. Replacement seat tubes are $496, and take about three days to swap out.

Dang. And dang again.

(I'm guessing the fellow who sold me the frame did not notice the incipient crack himself.)

Thanks all for your help and suggestions. I much appreciate it!

Dave, who reiterates that on the used side of the aisle he will stick with steel and titanium frames in the the future...not that he needs any more bikes

[NateM]

Dave,
a couple of years back I cracked the seat tube on my Calfee frame in a similar way. I was having the frame repainted by Calfee and had them repair the seat tube. Here is a quote from their repair shop before receiving my frame."Our cost for fixing a seat tube crushed by the FD clamp is generally $75-$150, depending on the extent of the damage." Here is a pix of the damage, which looks far worse than yours. They ended up charging me $50 for the repair,of course that was included in the total bill for repaint which may have lowered the cost. Also my frame is painted which conceals the repair. Its worth at least a phone call to them for an estimate before committing to a replacement. Nate Merrill