Frame at Risk?
11-17-17 | 01:37 PM
#1
Thread Starter
Junior Member
Joined: Mar 2007
Posts: 12
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Frame at Risk?
Hello,
Would appreciate any input on an issue I'm having:
2009 Specialized Allez Comp with Alumninum frame and carbon rear triangle with concern for corrosion. I ride 4 seasons in the Northeast, with regular care and maintenance, racking up 25k+ miles. Crashed twice in local races without any apparent damage. Over the past 6 months, I have noticed bubbling and cracking of the paint due what I assume is corrosion at the joint between the aluminum and carbon rear triangle on the seat stay, 2" below the seat cluster. It's progressed, and is now circumferential, focused at this 1" thick spot. My LBS was not too concerned, thought it was superficial. Pics below.
Should I do anything further to work it up? Is it reasonable to keep riding?
Thanks!
Would appreciate any input on an issue I'm having:
2009 Specialized Allez Comp with Alumninum frame and carbon rear triangle with concern for corrosion. I ride 4 seasons in the Northeast, with regular care and maintenance, racking up 25k+ miles. Crashed twice in local races without any apparent damage. Over the past 6 months, I have noticed bubbling and cracking of the paint due what I assume is corrosion at the joint between the aluminum and carbon rear triangle on the seat stay, 2" below the seat cluster. It's progressed, and is now circumferential, focused at this 1" thick spot. My LBS was not too concerned, thought it was superficial. Pics below.
Should I do anything further to work it up? Is it reasonable to keep riding?
Thanks!
11-17-17 | 01:54 PM
#2
Senior Member
Joined: Jul 2015
Posts: 7,476
Likes: 3,287
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
you're the proud father of Aluminum Oxide... it is white-ish, and annoying...
left alone, it will eventually eat right through the tubing, but that will take many more years than your life has left.... the problem to be aware of is CRACKING at the pits the oxidation will create... the pits act a STRESS RISERS, and they foster cracking.
in the meantime... sanding away all traces of the oxidation then properly repainting will end it's existence for now... it will return, eventually.... filling any deep pitting with JB Weld will reduce the stress riser factor some.
any and all other violations of the paint will allow more oxidation to occur... all it takes is water and aluminum in contact with each other to grow.
this is a fairly common issue with aluminum frames, btw... KHS, Trek, and Cannondale are quite famous for such oxidation issues... more a prep/primer/paint issue with certain models/years.
left alone, it will eventually eat right through the tubing, but that will take many more years than your life has left.... the problem to be aware of is CRACKING at the pits the oxidation will create... the pits act a STRESS RISERS, and they foster cracking.
in the meantime... sanding away all traces of the oxidation then properly repainting will end it's existence for now... it will return, eventually.... filling any deep pitting with JB Weld will reduce the stress riser factor some.
any and all other violations of the paint will allow more oxidation to occur... all it takes is water and aluminum in contact with each other to grow.
this is a fairly common issue with aluminum frames, btw... KHS, Trek, and Cannondale are quite famous for such oxidation issues... more a prep/primer/paint issue with certain models/years.
Last edited by maddog34; 11-17-17 at 02:01 PM.
11-17-17 | 02:02 PM
#3
Senior Member
Joined: May 2003
Posts: 4,056
Likes: 166
From: Mountain Brook. AL
I would suspect this to be early manifestation of joint bond degradation between the aluminum and carbon, usually some sort of epoxy.
It is mostly a surface phenomenon hence the bubbling and likely the epoxy inside the joint is intact. Aluminum oxidation is possible
but I think the epoxy is a more likely explanation. Sanding down the area would help delineate this but can be deferred. This is
almost certainly not a butt joint but a slip joint with some tubing inside the other and epoxy as the interface. When the paint begins
to pop off you can investigate further but I would keep riding.
You can google aluminum corrosion and get various opinions eg: https://www.proboat.com/2014/12/keep...t-on-aluminum/
This kind of cosmetic joint degradation was common on Trek bikes in the '90s when straight carbon tubes were bonded to cast aluminum
lugs mostly clear coated rather than painted.
It is mostly a surface phenomenon hence the bubbling and likely the epoxy inside the joint is intact. Aluminum oxidation is possible
but I think the epoxy is a more likely explanation. Sanding down the area would help delineate this but can be deferred. This is
almost certainly not a butt joint but a slip joint with some tubing inside the other and epoxy as the interface. When the paint begins
to pop off you can investigate further but I would keep riding.
You can google aluminum corrosion and get various opinions eg: https://www.proboat.com/2014/12/keep...t-on-aluminum/
This kind of cosmetic joint degradation was common on Trek bikes in the '90s when straight carbon tubes were bonded to cast aluminum
lugs mostly clear coated rather than painted.
Last edited by sch; 11-17-17 at 02:08 PM.
