Go Back  Bike Forums > Bike Forums > Tandem Cycling
Reload this Page >

What's happening to this carbon Wound Up fork?

Notices
Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

What's happening to this carbon Wound Up fork?

Old 03-16-14, 03:03 PM
  #1  
Member
Thread Starter
 
tstansbury's Avatar
 
Join Date: Nov 2011
Location: Falls Church, VA
Posts: 35

Bikes: Seven Ti Tandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
What's happening to this carbon Wound Up fork?

Our Wound Up Tandem Duo fork is showing discoloration/spotting where the brakes attach to the fork. The clear coat is clean and feels mostly smooth to the touch, except right at the metal/carbon junction. The fork is designed for both disc and linear pull brakes, although to date we have used only the linear pull. The problem areas are next to both brakes. The rest of the fork looks clear. The fork is two years old, with roughly 7,000-8,000 miles. Bike frame is ti. Team is 310 pounds.

Our retailer (Mel at Tandems East) is to talk to the manufacturer. Also, a local carbon repair guru will have a look at it. In the meantime, we're curious if anyone has had a similar experience or has a theory about what's happening. If this is merely cosmetic, we don't care much. If it's potentially more than cosmetic, then obviously we care a ton.

Appreciate your thoughts. Cheers all!

Attached Images
File Type: jpg
disc.jpg (86.8 KB, 60 views)
File Type: jpg
closeup2.jpg (88.4 KB, 71 views)
File Type: jpg
IMG_2214.jpg (89.7 KB, 75 views)
File Type: jpg
closeup1.jpg (88.1 KB, 74 views)
tstansbury is offline  
Old 03-16-14, 03:22 PM
  #2  
Senior Member
 
waynesulak's Avatar
 
Join Date: Jan 2008
Location: Ft Worth, TX
Posts: 1,971

Bikes: Custom 650B tandem by Bob Brown, 650B tandem converted from Santana Arriva, Santana Noventa, Boulder Bicycle 700C, Gunnar Sport

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
I noticed on the only picture that shows below that attachment that it appears that the problem is above but not below the metal. It this the case at all locations?
waynesulak is offline  
Old 03-16-14, 04:17 PM
  #3  
Member
Thread Starter
 
tstansbury's Avatar
 
Join Date: Nov 2011
Location: Falls Church, VA
Posts: 35

Bikes: Seven Ti Tandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by waynesulak
I noticed on the only picture that shows below that attachment that it appears that the problem is above but not below the metal. It this the case at all locations?
Hmm, there should be links to four pics. As for your question, the bike's in the shop now, but if I recall correctly, the affected areas appear above the metal in all cases.
tstansbury is offline  
Old 03-16-14, 04:35 PM
  #4  
just another gosling
 
Carbonfiberboy's Avatar
 
Join Date: Feb 2007
Location: Everett, WA
Posts: 19,486

Bikes: CoMo Speedster 2003, Trek 5200, CAAD 9, Fred 2004

Mentioned: 115 Post(s)
Tagged: 0 Thread(s)
Quoted: 3866 Post(s)
Liked 1,911 Times in 1,362 Posts
I have a very similar '03 WU fork. It's seen a lot of use and bad weather, and is fine. When I look very closely at the top of the junction between carbon and aluminum on my fork, I see that the junction is filled to the top with some shiny material, probably epoxy resin. This is typical of such attachments and is called hardware bonding.

In your photographs, it looks like there is a gap between carbon and aluminum that was not resin filled and some substance is bubbling out of that gap. It is possible to get galvanic corrosion between carbon and aluminum because they are dissimilar metals, far away from each other in electrical potential. For this to happen, they have to touch each other. Well designed and built parts will have the aluminum and carbon insulated from each other with epoxy. However, it is possible that somewhere under the aluminum, it is in contact with the carbon and that what you are seeing are corrosion products of the aluminum because water and other electrolytes are getting into this gap. In these cases, the carbon is not damaged, but the aluminum goes away until it crumbles. I have had this happen on a carbon bike.

In your case, it seems probable that, if this is corrosion, it is limited to a small area at the top of the brake holder and is not too much of a worry. However, if I'm correct, WU should do something for you toward a new fork. This is not supposed to happen.
Carbonfiberboy is offline  
Old 03-16-14, 05:59 PM
  #5  
Senior Member
 
Join Date: Feb 2013
Location: Gypsum, CO
Posts: 289

Bikes: Litespeed Obed, Cannondale Scalpel, Spcialized AWOL, Litespeed Solano, Cannondale Synapse

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I am most certainly not qualified to diagnose your issue here but it looks like a bit of galvanic corrosion is messing with your clear coat.
mtn.cyclist is offline  
Old 03-21-14, 04:17 PM
  #6  
Member
Thread Starter
 
tstansbury's Avatar
 
Join Date: Nov 2011
Location: Falls Church, VA
Posts: 35

Bikes: Seven Ti Tandem

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Quick update... No formal response back from Wound Up yet, but a local carbon specialist looked at the folk. He thinks the discoloration is likely due to oxidization occuring under the clear coat, and that the carbon fiber is fine. Gold star in the margin to CFB for being the first to identify the culprit. While this doesn't seem like something that should happen to a high-end component, at least the initial report on the fork's integrity is reassuring.

Now, if somebody would please do something to stop the snowshowers and 20-degree temps we're being threatened with in a couple of days. Yeef, enough already, it's supposed to be spring.
tstansbury is offline  
Old 03-23-14, 06:09 AM
  #7  
Senior Member
 
SJX426's Avatar
 
Join Date: May 2008
Location: Fredericksburg, Va
Posts: 9,563

Bikes: '65 Frejus TDF, '73 Bottecchia Giro d'Italia, '83 Colnago Superissimo, '84 Trek 610, '84 Trek 760, '88 Pinarello Veneto, '88 De Rosa Pro, '89 Pinarello Montello, '94 Burley Duet, 97 Specialized RockHopper, 2010 Langster, Tern Link D8

Mentioned: 73 Post(s)
Tagged: 0 Thread(s)
Quoted: 1598 Post(s)
Liked 2,181 Times in 1,086 Posts
I would have guessed the same action. The question is why is there oxidation occurring? Somehow, water or air is getting into a sealed joint or through a protective cover. It should be addressed.
SJX426 is offline  
Old 03-23-14, 05:12 PM
  #8  
PMK
Senior Member
 
PMK's Avatar
 
Join Date: May 2008
Location: Royal Palm Beach, Florida
Posts: 1,236

Bikes: 2006 Co-Motion Roadster (Flat Bars, Discs, Carbon Fork), Some 1/2 bikes and a couple of KTM's

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 28 Post(s)
Likes: 0
Liked 1 Time in 1 Post
I would have a difficult time with that evaluation. All my experience with these corrosion issues always see the corrosion stem outward from the aluminum. Your photo has speckles of clear coat "concerns".

The likelihood that you see corrosion on top of carbon, where it blisters the clear seems very remote. If there is visible corrosion on the aluminum adhesive bonded items, then you have a serious problem.

Often, to insulate the aluminum from the carbon, a scrim cloth of fiberglass is placed between the dissimilar materials.

I am probably wrong, but my opinion is the fork flexing has caused small disbonds to the clear coat. We have a similar version of a WU fork, it does move around a bit.

PK
PMK is offline  
Old 03-24-14, 06:07 AM
  #9  
pel
Senior Member
 
Join Date: Oct 2004
Location: Perth WA
Posts: 177
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Definitely speak to WU. This should not happen and you/we have no idea how it might progress. It's in WU's interests to know about this and if needs be replace. Good luck. They replaced for me recently even though over warranty (different problem - fine cracks - see earlier post).
pel is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
AFoe
Bicycle Mechanics
4
10-20-15 03:05 PM
oisiaa
Road Cycling
40
05-04-14 01:17 PM
eliott
Bicycle Mechanics
7
10-09-12 03:04 PM
striker27
Road Cycling
16
08-30-12 07:49 PM

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.