Cycling UK Forum

Any advice gratefully received; Is my poor bike beyond help? What's happening to it?

I just got my rarely used trusty Vantage out of the shed to find patches of white stuff growing. Is this corrosion? Does it mean the bike is screwed? How do I stop it?

Eeeek

Have you had something metallic leaning on it? What happens if you push the patch with your finger?

Spilt paint stripper on it?

Aluminium produces a white corrosion product (its version of rust) so it is certainly corroding. The answer must be something along the lines of clean and paint, assuming the corrosion has not gone too far.

Great ideas, good thinking. I'll go back to the shed and see what was on he shelf above it.

A previous thread on the subject.

viewtopic.php?f=5&t=91475

looks like salt corrosion to me.

I see that type of corrosion quite frequently on ships.

Many valve actuators (for example) are manufactured of aluminium alloy & clagged onto a steel valve or similar.

In a salt laden environment it doesn't take long for the corrosion to set in & some of the actuators appear to 'burst' underneath a fairly intact paint film. Coating with a 2 pack epoxy primer can prolong the life somewhat but once the corrosion sets in it's very hard to stop. Scrap it & buy a new bike!!

All the best, Simon

once such corrosion starts it is difficult to stop. Alkaline and/or chloride bearing environments are commonly associated with such corrosion.

If you wish to treat it, I'd advise trying to re-passivate the surface by treating it with an acid of some kind, having removed any loose paint and white powdery nonsense. Having done that, a decent primer (for aluminium) and paint may restore the frame to usable condition. {BTW Wax-based treatments (eg waxoyl) can help to slow down corrosion, even though they are really meant for use on steel.]

However you may find that there is pitting corrosion when you clean it up; IME this is very commonplace if you see corrosion of this sort anywhere near a weld in a typical aluminium frameset.

BTW it is as well to remember that Aluminium is actually a highly reactive metal. The only reason it doesn't spontaneously combust is that it usually has a coherent oxide film that acts as a diffusion barrier; this being the case it should hardly come as any surprise that it will corrode in some circumstances.

cheers

Get that type of powerdery corrosion on my motor bike brakes which are alloy - lift the paint off and turns into a white dust, hard to treat once it has started?

When you inspect the area where the bike was kept, look out for anything metallic which might have been in contact and acted as a earth conductor. As stated above, Aluminium is highly reactive when the normal surface film is removed by salts etc. However - if the bike is grounded, the corrosion can be accelerated.