Too much info

[02GF74]

hmmm I have 2 aluminum frame road bikes - one is a very cheap no brand and other is top notch Bianchi. Both have some corrosion on the top tube; th no brand is much worse thanksully! - I will try to get some photos. compare this with my steel framed '94 saracen mtb, dating back from when saracen made top notch bikes - as good as new, ok some small scrapes as it is the main commuter but nothing like the corrosion on the aluminium bikes.

 

[fossyant]

Alloy corrosion isn't half as 'bad' as corrosion on steel - it's just unslightly and hard to stop !

 

[Joe24]

I have a slightly worry about my fixed. Its an old 531 frame(same age as me, so its 17) and on the back, by the bottom bracket at the back, where it forks out and around the lugs for the bottom bracket coming down from the seat tube, the paint has cracked and its got rust there.
Ive looked at it, and couldnt work it out. Only thing i can put it down to is the frame flexing and the paint just cracking and opening out.
But im not sure
The handlebars creak and crack abit when im pulling hard on them aswell

 

[Smokin Joe]

hmmm I have 2 aluminum frame road bikes - one is a very cheap no brand and other is top notch Bianchi. Both have some corrosion on the top tube; th no brand is much worse thanksully! - I will try to get some photos. compare this with my steel framed '94 saracen mtb, dating back from when saracen made top notch bikes - as good as new, ok some small scrapes as it is the main commuter but nothing like the corrosion on the aluminium bikes.

Corrosion is caused when bare metal is exposed to the elements, it is not due to a material fault. Take a bit of a steel tube back to bare metal and within 24 hours it will show signs of rusting.

 

[02GF74]

Corrosion is caused when bare metal is exposed to the elements, it is not due to a material fault. Take a bit of a steel tube back to bare metal and within 24 hours it will show signs of rusting.

That may be fine and dandy but the Al frames are painted over in the places they have corroded.

 

[02GF74]

by the bottom bracket at the back, where it forks out and around the lugs for the bottom bracket coming down from the seat tube, the paint has cracked and its got rust there.
Ive looked at it, and couldnt work it out. Only thing i can put it down to is the frame flexing and the paint just cracking and opening out.
But im not sure

or it could be a crack in the frame? one way to test it would be to temporarily bung up the frame tubes and get some compressed air inside it. Then spray some soapy water where the paint has cracked - if the frame has gone, it will blow big bubbles!