Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 10-14-09, 07:18 PM   #1
johnrpowell
Junior Member
Thread Starter
 
Join Date: Jul 2008
Bikes:
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
derailleur clamp mark on carbon fiber seat tube

I just purchased a used 2007 Bianchi 928 SL frame and while building it up, noticed a dent in the seat tube where a derailleur clamp had been. It appears as if the tube is dented and pinched, but I'm not sure if this is just the clear coat or if the tube itself has been structurally compromised. Is this something I should be worried about?

johnrpowell is offline   Reply With Quote
Old 10-14-09, 07:21 PM   #2
I_bRAD
Call me The Breeze
 
I_bRAD's Avatar
 
Join Date: Aug 2006
Location: Corbyville Ontario
Bikes: 2004 Litespeed Siena, 1996 Litespeed Obed, 1992 Miele (unknown model), 1982 Meile Uno LS.
Posts: 3,699
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
nice books nerd
I_bRAD is offline   Reply With Quote
Old 10-14-09, 07:24 PM   #3
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Bikes: 1987 Bianchi Campione
Posts: 28,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
lal
operator is offline   Reply With Quote
Old 10-14-09, 07:26 PM   #4
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Bikes: Trek 5500, Colnago C-50
Posts: 9,433
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I think it will be OK to ride.
I don't understand why some manufacturers use clamp-on derailleurs on carbon fiber frames when most use a "braze-on" type. Carbon fiber usually has very high tensile strength but lower compressive strength.

Al

Last edited by Al1943; 10-14-09 at 07:43 PM.
Al1943 is offline   Reply With Quote
Old 10-14-09, 08:29 PM   #5
johnrpowell
Junior Member
Thread Starter
 
Join Date: Jul 2008
Bikes:
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I'm hoping that first comment was a joke. Do people really spend their time trolling on this thing just to make the first pointless statement on every message thread? But I digress...

I definitely agree--it makes little sense to me why manufacturers continue to use clamp-on derailleurs in some instances. The 928 SL was one of their higher-end frames for that year; you'd think they would use the most sensible technologies on it.

Here are a few clearer images of the area in question:





johnrpowell is offline   Reply With Quote
Old 10-15-09, 12:06 AM   #6
Panthers007
Great State of Varmint
 
Panthers007's Avatar
 
Join Date: Sep 2008
Location: Dante's Third Ring
Bikes:
Posts: 7,479
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I'd take it to a reputable shop that deals with carbon - and have them test it for any damage below the outer coating. Anyone who is planning on attaching components to a carbon-frame or fork MUST have a suitable torque-wrench(s). Just a little over tightening and you can kiss any warranties bye, bye. As well as possible getting you injured or killed.

Torque-wrench, and learn how to use them.

<EDIT> The trolls are part-time. Relax.
Panthers007 is offline   Reply With Quote
Old 10-15-09, 12:45 AM   #7
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,847
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 872 Post(s)
I wouldn't sweat it.

It appears to simply be cosmetic, and in any case isn't in a critical, highly stressed area. What I would do is find some decorative sticky material and make a band to cover it, and possibly a second higher on the seat tube to make it seem part of the original frame decoration.

I'm not a fan of carbon because of it's tendency to fail catastrophically without warning, but I wouldn't worry about this causing a failure in my lifetime.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline   Reply With Quote
Old 10-15-09, 01:09 AM   #8
Panthers007
Great State of Varmint
 
Panthers007's Avatar
 
Join Date: Sep 2008
Location: Dante's Third Ring
Bikes:
Posts: 7,479
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I'd have it looked/listened at. The OP said it was a discernible bend and scarring. That's grounds for a full check-up. At least in my book.
Panthers007 is offline   Reply With Quote
Old 10-15-09, 01:23 AM   #9
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,847
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 872 Post(s)
Let's be real, it might have been cause for concern before buying the frame, but that bridge is already closed. Yes, he could bring it to a mechanic, but very few (if any) LBS mechanics are any more qualified or equipped to pass judgement on this than he is.

he could apply the adage "if in doubt, throw it out" but where does that get him. In assessing the his real risk he can apply a bit of risk assessment logic. Where the consequences of failure would be very serious such as a fork steerer only a tiny risk is acceptable, but where the consequences of failure are low, a greater amount of risk would be acceptable.

In this case, while the chances of failure aren't known, we do know that it isn't a highly stressed area of the frame, and unlikely to fail suddenly without some warning. In any case a seat tube failure is unlikely to cause a crash and injury, so from a risk assessment standpoint riding this frame isn't any more unreasonable than riding any bike out in traffic.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline   Reply With Quote
Old 10-15-09, 07:38 AM   #10
DaveSSS
Senior Member
 
Join Date: Sep 2008
Location: Loveland, CO
Bikes: Two LOOK 585s, one KG461
Posts: 4,987
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
There is no "test" that can be performed for damage by a LBS. From the pictures, this is only clearcoat damage, but it's also an example where someone applied far too much torque to the derailleur clamp.

I'd be inclined to sand the area with 600-1000 grit sandpaper (wet) to smooth up the ridges.

I have three CF frames that use clamp-on FDs and I've never had any problem at all. The problem is ignorant mechanics.

I prefer to use a Campy or Shimano clamp-on adapter with a braze-on FD. I consider the adapter part of the frame and rarely remove it.
DaveSSS is offline   Reply With Quote
Old 10-15-09, 10:00 AM   #11
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Bikes: 1987 Bianchi Campione
Posts: 28,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by DaveSSS View Post
There is no "test" that can be performed for damage by a LBS.
What if I told you we had an x-ray machine?
operator is offline   Reply With Quote
Old 10-15-09, 10:38 AM   #12
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,847
Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 872 Post(s)
Quote:
Originally Posted by operator View Post
What if I told you we had an x-ray machine?
And?

X-rays are not capable of detecting stress micro fractures in carbon structures.

The OP will not be able to get any qualified, meaningful determination of the structural damage (if any) at anything below what the frame is worth.

It's a calculated risk whether to ride it or not. It's the OPs risk, and therefore his judgment call.

As I said earlier, in his shoes I'd ride it and not sweat it. He could and should cover the damage, both for cosmetics, but more importantly so that water doesn't enter the matrix through the cracked clear coat. Assuming he'll be mounting a FD on the frame he might see if he can get the same model as was used previously, though it won't make much difference either way.

BTW- I'm not being fatalistic, or taking a casual attitude about the possible risks. If I found similar damage in a more critical area, near a head joint, or on a fork, I'd scrap the frame without giving it a second thought.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline   Reply With Quote
Old 10-15-09, 06:30 PM   #13
johnrpowell
Junior Member
Thread Starter
 
Join Date: Jul 2008
Bikes:
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks for all of your help and comments. I took the bike to a very reputable bike shop in my area that is a Bianchi dealer and one of their head mechanics inspected it. His opinion was that the damage was structural and that the carbon fiber was cracked. He concurred that it's not in a high-stress area, but it is likely that the crack would grow over time. I could hope for the best and ride it, but considering how much money I paid for it, I'm just going to get my money back and return to my reliable aluminum frame for now.

Thanks again!
johnrpowell is offline   Reply With Quote
Old 10-15-09, 06:35 PM   #14
I_bRAD
Call me The Breeze
 
I_bRAD's Avatar
 
Join Date: Aug 2006
Location: Corbyville Ontario
Bikes: 2004 Litespeed Siena, 1996 Litespeed Obed, 1992 Miele (unknown model), 1982 Meile Uno LS.
Posts: 3,699
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Sounds like a good plan. It sucks when you don't feel confident with your frame. You should enjoy the speed on a nice downhill and not have to worry if it's your last.
I_bRAD is offline   Reply With Quote
Old 10-15-09, 06:38 PM   #15
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Bikes: 1987 Bianchi Campione
Posts: 28,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by FBinNY View Post
And?

X-rays are not capable of detecting stress micro fractures in carbon structures.

The OP will not be able to get any qualified, meaningful determination of the structural damage (if any) at anything below what the frame is worth.

It's a calculated risk whether to ride it or not. It's the OPs risk, and therefore his judgment call.

As I said earlier, in his shoes I'd ride it and not sweat it. He could and should cover the damage, both for cosmetics, but more importantly so that water doesn't enter the matrix through the cracked clear coat. Assuming he'll be mounting a FD on the frame he might see if he can get the same model as was used previously, though it won't make much difference either way.

BTW- I'm not being fatalistic, or taking a casual attitude about the possible risks. If I found similar damage in a more critical area, near a head joint, or on a fork, I'd scrap the frame without giving it a second thought.
So the fact that colnago provides x-rays with their forks to prove that their are sound is just a marketing exercise?
operator is offline   Reply With Quote
Old 10-15-09, 07:05 PM   #16
rmac
Senior Member
 
Join Date: May 2005
Bikes:
Posts: 573
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Not sure how much you paid for the frame, but you could send it to Calfee and have them look at it and repair it if needed.

Repair I think would be about $200 + $75 for clearcoat.

http://www.calfeedesign.com/howtosendrepair.htm
rmac is offline   Reply With Quote
Old 10-15-09, 10:09 PM   #17
Panthers007
Great State of Varmint
 
Panthers007's Avatar
 
Join Date: Sep 2008
Location: Dante's Third Ring
Bikes:
Posts: 7,479
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by rmac View Post
Not sure how much you paid for the frame, but you could send it to Calfee and have them look at it and repair it if needed.

Repair I think would be about $200 + $75 for clearcoat.

http://www.calfeedesign.com/howtosendrepair.htm
And we are trust these people and why? I wouldn't accept a "repaired" carbon-frame. I'd junk it, return it, anything but trust it enough to ride it. And I like their legal boilerplate:

"Under no circumstances shall Calfee Design be liable for any damages or injuries incurred by the use of the Repair Servise. This includes, but is not limited to: lost profits, lost savings, and incidental or consequential damages or injuries arising from the use of, or inability to use this product. The limited warranty set forth in this agreement may not be extended or modified by any Calfee Design Dealer, Agent or Employee. Calfee Design does not assume any liability or make any warranty except as stated in this limited warranty. This warranty gives you specific legal rights, and you may also have other rights depending on your state. Some states do not allow limitations on the duration of implied warranties, or the limitation or exclusion of incidental or consequential damages; therefore, the limitations and exclusions set forth in this warranty may not apply to you. "

Panthers007 is offline   Reply With Quote
Old 10-16-09, 08:45 AM   #18
rmac
Senior Member
 
Join Date: May 2005
Bikes:
Posts: 573
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Quote:
Originally Posted by Panthers007 View Post
And we are trust these people and why? I wouldn't accept a "repaired" carbon-frame. I'd junk it, return it, anything but trust it enough to ride it. ...
Uh, I would trust them because:

"We are proud to offer the benefit of our 20 years experience with composites to the owners of all carbon bike frames. Many major carbon frame companies refer riders to us for their frame repairs, and to help solve design issues. Hundreds of bike shops from across the U.S., Canada, Asia, and Europe have been able to provide their customers with an affordable alternative to Crash Replacements.

Our unique molding process uses the best quality 3k carbon fiber weave to create forms that are shapely, lightweight, and extremely strong. From minor scratches to stuck seatposts to frames destroyed by the dreaded endo or that startling encounter with the garage door; we've repaired over 2,100 frames since 2003."

Also, they built my bike and it hasn't fallen apart or had a catastrophic failure.
rmac is offline   Reply With Quote
Old 10-16-09, 12:40 PM   #19
njkayaker
Senior Member
 
Join Date: Sep 2007
Bikes:
Posts: 9,636
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 206 Post(s)
Quote:
Originally Posted by Panthers007 View Post
And we are trust these people and why? I wouldn't accept a "repaired" carbon-frame. I'd junk it, return it, anything but trust it enough to ride it. And I like their legal boilerplate:

"Under no circumstances shall Calfee Design be liable for any damages or injuries incurred by the use of the Repair Servise. This includes, but is not limited to: lost profits, lost savings, and incidental or consequential damages or injuries arising from the use of, or inability to use this product. The limited warranty set forth in this agreement may not be extended or modified by any Calfee Design Dealer, Agent or Employee. Calfee Design does not assume any liability or make any warranty except as stated in this limited warranty. This warranty gives you specific legal rights, and you may also have other rights depending on your state. Some states do not allow limitations on the duration of implied warranties, or the limitation or exclusion of incidental or consequential damages; therefore, the limitations and exclusions set forth in this warranty may not apply to you. "

Such "legal boilerplate" is probably typical for most types of repairs (it's not restricted to repairs of carbon frames).
njkayaker is offline   Reply With Quote
Old 10-16-09, 01:48 PM   #20
Panthers007
Great State of Varmint
 
Panthers007's Avatar
 
Join Date: Sep 2008
Location: Dante's Third Ring
Bikes:
Posts: 7,479
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
True, but I'd still feel I was riding on borrowed time. So I'd be rid of it. The OP is off to return his. His option - and what I'd do too. If I had that option available. Otherwise I'd junk it and take my lumps - making sure to better inspect such before money was exchanged.
Panthers007 is offline   Reply With Quote
Old 10-16-09, 02:06 PM   #21
TRaffic Jammer
Dances With Cars
 
TRaffic Jammer's Avatar
 
Join Date: Jan 2006
Location: Toronto, Canada
Bikes: TBL Onyx Pro(ss converted), Pake SS (starting to look kinda pimped)
Posts: 10,527
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I have a 928 waiting to be built up and I was concerned about that as well.
TRaffic Jammer is offline   Reply With Quote
Old 10-16-09, 02:36 PM   #22
I_bRAD
Call me The Breeze
 
I_bRAD's Avatar
 
Join Date: Aug 2006
Location: Corbyville Ontario
Bikes: 2004 Litespeed Siena, 1996 Litespeed Obed, 1992 Miele (unknown model), 1982 Meile Uno LS.
Posts: 3,699
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
hurry up and get it built before the snow flies!
I_bRAD is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 11:20 AM.