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I have a CAAD 9, about 6 years old. This summer seems to have been hard on the frame with the high temps and humidity. At the bottom of the bottom bracket it appears that quite a bit of corrosion took hold -- a lot of bumps under the paint. Although it looks terrible, it's still hard -- I can press/scrape against it with a small screwdriver and the paint doesn't yield.

Anyone know if with the aluminum if this will mainly just be cosmetic and a reminder to hose down the bike after a ride, or should I have the affected area stripped, cleaned and repainted? I don't think it should really compromise the strength of the frame.
 
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I would def have it cleaned up. It may be rusted under the paint. I would have it sanded down and re-painted just to be on the safe side. Another thing, idk if you'd be willing to do this but i have frame saver inside my frame to prevent such things from happening. Be somthing to look into.
 

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yank my crank said:
I would def have it cleaned up. It may be rusted under the paint. I would have it sanded down and re-painted just to be on the safe side. Another thing, idk if you'd be willing to do this but i have frame saver inside my frame to prevent such things from happening. Be somthing to look into.
Aluminum doesn't rust. It can oxidize though. Semantics, I know :D

ArkRider said:
I have a CAAD 9, about 6 years old. This summer seems to have been hard on the frame with the high temps and humidity. At the bottom of the bottom bracket it appears that quite a bit of corrosion took hold -- a lot of bumps under the paint. Although it looks terrible, it's still hard -- I can press/scrape against it with a small screwdriver and the paint doesn't yield.

Anyone know if with the aluminum if this will mainly just be cosmetic and a reminder to hose down the bike after a ride, or should I have the affected area stripped, cleaned and repainted? I don't think it should really compromise the strength of the frame.
Galvanic corrosion was a fairly common problem on cannondale's alumnium/carbon frames like the Six13 and System Six from a few years ago. I haven't seen it on too many CAAD9's - most of the time people noticed it on clearcoated brushed aluminum frames. You could see spiderwebbing that appeared to be under the clearcoat. It seemed that most of the time this corrosion was considered cosmetic only and occurred near interfaces between carbon and the aluminum.

However, I'd still get your frame checked out by an expert for piece of mind. The BB experiences a lot of stress and you definitely wouldn't want it to be compromised in any way.

 

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Ive just been stripping my old Super V 500 and found a few area's looking like that pic above,
it seems to clear using some wire wool although Il be using wet n dry,
In a few places were a few touches of white powder (oxidising) but its all cleaned up pretty well,

KK..:)
 

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Re-paint

ArkRider said:
I have a CAAD 9, about 6 years old. This summer seems to have been hard on the frame with the high temps and humidity. At the bottom of the bottom bracket it appears that quite a bit of corrosion took hold -- a lot of bumps under the paint. Although it looks terrible, it's still hard -- I can press/scrape against it with a small screwdriver and the paint doesn't yield.

Anyone know if with the aluminum if this will mainly just be cosmetic and a reminder to hose down the bike after a ride, or should I have the affected area stripped, cleaned and repainted? I don't think it should really compromise the strength of the frame.
While the metal is pretty thick on the BB shell, if this was a bike I was planning to keep or to try to sell for real $$ then I would definitely fix this. It is surely oxidation under the paint and soon enough that paint will start to peel. I have this on my old commuter Cannondale but I couldn't care less about this bike so I haven't done anything about it.
 
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