PdeB Posted October 28, 2022 Share Hi all Has any of you seen this on an aluminium mtb frame? It's right where the seat post goes into the frame. The frame is only a few years old (2019) and has not been exposed to hazardous conditions. Other than for this, the frame is in an excellent condition. My LBS says I should approach the manufacturer (which I've done), to ask if this is covered by warranty, but if not, I shouldn't worry about it too much. I do not want to mention the bike brand at this stage as I don't want to jeopardise any potential warranty claim I may have. Thanks Link to comment Share on other sites More sharing options...
Barry Posted October 28, 2022 Share 26 minutes ago, PdeB said: Hi all Has any of you seen this on an aluminium mtb frame? It's right where the seat post goes into the frame. The frame is only a few years old (2019) and has not been exposed to hazardous conditions. Other than for this, the frame is in an excellent condition. My LBS says I should approach the manufacturer (which I've done), to ask if this is covered by warranty, but if not, I shouldn't worry about it too much. I do not want to mention the bike brand at this stage as I don't want to jeopardise any potential warranty claim I may have. Thanks Looks like galvanic corrosion . If it is a carbon frame or seat post then it could be a reaction between the carbon and aluminum. Carbon assembly paste would have limited the effects of the reaction. Edited October 28, 2022 by Barry Link to comment Share on other sites More sharing options...
PdeB Posted October 28, 2022 Share 10 minutes ago, Barry said: Looks like galvanic corrosion . If it is a carbon frame or seat post then it could be a reaction between the carbon and aluminum. Carbon assembly paste would have limited the effects of the reaction. Both the frame and the seat post are aluminium. Barry 1 Link to comment Share on other sites More sharing options...
Barry Posted October 28, 2022 Share 2 minutes ago, PdeB said: Both the frame and the seat post are aluminium. What started as a small paint chip could have allowed moisture to get under the paint and it started corrosion. Hi pressure wash can force water and detergent under the paint and if not rinsed off can react with the aluminum. dasilvarsa 1 Link to comment Share on other sites More sharing options...
Barry Posted October 28, 2022 Share The white powdery stuff in the pic is defiantly corrosion. Same as the red color that you would get from steel when rust starts. dasilvarsa 1 Link to comment Share on other sites More sharing options...
RiverInTheRoad Posted October 28, 2022 Share It looks like a manufacturing defect. Should be covered under warranty IMO. Headshot and dasilvarsa 2 Link to comment Share on other sites More sharing options...
PdeB Posted October 28, 2022 Share 5 minutes ago, Barry said: What started as a small paint chip could have allowed moisture to get under the paint and it started corrosion. Hi pressure wash can force water and detergent under the paint and if not rinsed off can react with the aluminum. I've had the bike since new and I don't use a high pressure washer or detergent when I wash my bike. I use a normal hose and a damp cloth. From my understanding (a bit of googling) aluminium does not normally corrode unless it's exposed to salt. Surely it is not normal for an aluminium frame which is kept clean and indoors to corrode after only a few years, or am I mistaken? Link to comment Share on other sites More sharing options...
FondTF2 Posted October 28, 2022 Share Could be as a result of overtightening the seat post clamp? Nothing a bit of black nail polish cant fix. dasilvarsa 1 Link to comment Share on other sites More sharing options...
Barry Posted October 28, 2022 Share 1 minute ago, PdeB said: I've had the bike since new and I don't use a high pressure washer or detergent when I wash my bike. I use a normal hose and a damp cloth. From my understanding (a bit of googling) aluminium does not normally corrode unless it's exposed to salt. Surely it is not normal for an aluminium frame which is kept clean and indoors to corrode after only a few years, or am I mistaken? Salt and some detergents may cause corrosion. But if you haven't used anything then tough to explain. Maybe wait for the manufacturer could well be a factory fault and you score a new frame. dasilvarsa 1 Link to comment Share on other sites More sharing options...
Barry Posted October 28, 2022 Share Galvanic corrosion is not limited to carbon on aluminum. It will happen when any dissimilar metals are in contact with each other. 6061 and 7075 could react. dasilvarsa 1 Link to comment Share on other sites More sharing options...
PdeB Posted October 28, 2022 Share 8 minutes ago, Barry said: Salt and some detergents may cause corrosion. But if you haven't used anything then tough to explain. Maybe wait for the manufacturer could well be a factory fault and you score a new frame. Thank you very much for your insights. Link to comment Share on other sites More sharing options...
PdeB Posted October 28, 2022 Share 5 minutes ago, Barry said: Galvanic corrosion is not limited to carbon on aluminum. It will happen when any dissimilar metals are in contact with each other. 6061 and 7075 could react. Noted, although I would hope that the manufacturer would know this and would not mismatch metals when building a bike. The seat post is the original one the bike came out with. I will wait and see what the manufacturer says. dasilvarsa and Barry 2 Link to comment Share on other sites More sharing options...
Barry Posted October 28, 2022 Share As for salt it would be interesting to see if other hubbers can pinpoint salt as a cause of corrosion. The sweat from your body falls on your bike. I have seen it on a bike stem the bike lived on an indoor trainer. Edited October 28, 2022 by Barry dasilvarsa 1 Link to comment Share on other sites More sharing options...
Eldron Posted October 28, 2022 Share That looks like good old fashioned corrosion caused by poor coating. All the little bumps in the paint around the visible corrosion are spots where the alu is oxidising under the paint. Do you live near the coast? Salt is terrible for alu. It is only a surface problem though - a sand blast and respray should sort it out. Headshot, Barry and dasilvarsa 3 Link to comment Share on other sites More sharing options...
PdeB Posted November 9, 2022 Share Hi all Just thought I's give you an update. My warranty claim was approved, although I still don't know exactly why. I guess it is, as most of you suggested, corrosion. I'm now awaiting a replacement frame. I just hope the replacement is the same colour so it matches my fork. Thanks for your insights. RiverInTheRoad, Headshot, robbybzgo and 1 other 3 1 Link to comment Share on other sites More sharing options...
Headshot Posted November 9, 2022 Share Good to hear. My Spesh frame also developed similar localized corrosion in the vicinity of the forward shock mount. No damage to frame in that area and very obviously a coating defect. I just peeled off the loose paint, cleaned it and left it unpainted (luckily its not visible unless you try hard) Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now