The process has its true beginning right back during the processing stage. Metal ores extracted from the ground are melted, mixed with other metals and ingredients, then worked or machined into the parts that make up your bike.
During these processing stages oxygen is removed from the finished metal. When these metal parts now come into contact with oxygen in the air an electrochemical process known as Oxidisation takes place. Oxygen reacts with the metals surface to form metal oxides, essentially the metal is trying to revert back to it's original ore state.
For the most part this oxidisation is a naturally occurring action and on the whole would cause us very little problem other than dulling the surfaces of our metal parts. A little polishing will revive the shine. Motorbike manufacturers even
make use of the oxidisation process to protect certain
The addition of moisture to our otherwise benign oxidisation process turns it into a much more destructive monster....
Corrosion
components. Anodising for example artifically creates a thickened aluminium oxide coating that is the second hardest substances known after diamonds, and can be coloured with dyes to produce hard wearing and eye catching components for bikes.
As we said earlier, oxidisation is a natural electrochemical process. When moisture is added. this process is accelerated. Corrosion itself can be described as the point at which this accelerated oxidisation of the metal begins to show as damage. To understand how, we'll again try and keep it simple.
The corrosion process is another electrochemical process similar to the action of a battery.
A battery produces a current, (a current is simply a flow of electrons from one point to another). Two different metals are used to react with each other. Because each metal has a different chemical structure one of them will become the Anode, the negative (-) side which 'gives up' it's electrons while the other will becomes the Cathode (+) side which attracts them.
For these electrons to flow they need a circuit, a roadway between the two metals. In our diagram one side of this circuit is the wire joining the two metals, the other side is the liquid that the metals are sat in. This liquid is acidic water that forms an electrolyte.
On our bikes these different metals are all over the place. Steel bolts used to hold aluminium sections together, metals fused to form alloys, even on a single piece of metal very slight differences in chemical structure formed during the creation of the metal can produce positive and negitive areas, in other words Anodes and Cathodes!
We don't need a wire to connect these Anodes and Cathodes, they sit side by side completing one side of the circuit. All that's needed to complete the other side is an electrolyte ..... moisture. The process can proceed at any scale and doesn't require liquid water - water vapour alone is enough.
Surprisingly
research shows that winter is not the worse time for road salt corrosion. The arrival of Spring brings warmer air temperatures and higher humidity levels, these two factors allow salt residue trapped in the hidden areas of the bike to be activated producing a more corrosive action.
The second, and for us most important, factor is the moisture itself. Pure water is a poor electrolyte. To act as a good conductor it needs to absorb impurities to make it acidic. (If you're wondering why you only use pure distilled water to top up car/bike batteries, it's because the battery already contains acid. Only the water contents evaporates off and needs topping up).
Even tap water has impurities such as chlorines and fluorides, but for us a bigger killer is the waste gases and emissions produced by industry and vehicles getting onto the bike either as acid rain or road spray. Also during winter months thousands of tons of road salt are thrown down. The more concentrated these corrosive contaminants are and the longer they are in contact with moisture the more they'll be absobed to produce an acidic mix.
Power Stations - industries and vehicles release gases into the atmosphere
Sulphur dioxide and nitrogen oxides
Oxidisation in clouds produces sulphuric and nitric acid
Acid polluted air blown by winds
Water droplets absorb acids
How do you combat corrosion?
The more acidic the moisture, the more electrons can flow and therefore the more aggressive and damaging the corrosion.
Looked at in section you can see how the process resembles the actions of a battery
The key to success
for both storage and riding is to provide a barrier between your bike and any moisture present.
If you miss any areas then corrosion can form on the untreated section and spread.
Corroded starter relay compared to a new one.
With so many variables it starts to become clearer why one rider can have a bike for years with little sign of corrosion damage, while another with exactly the same bike will see signs of damage after just a few months.
degree of care and maintenance you carry out, all play a part. Manufacturers do put a lot of effort into ensuring your bike won't turn into a rust ball within a few months. Paint coatings, lacquers, components made from resistant alloys, are all designed to fight the effects of corrosion. However, mechanical damage from impact and even stone chips can open up avenues for corrosion, and of course price plays as issue, materials used and build quality may not always be what you'd wished.
What we've outlined above is a fairly simplistic and basic description of the corrosion process that affects our bikes. There is a lot more science to it, and no shortage of web sites you can visit to find out more. There are also other factors that have to be taken into account - what mileage you do, what conditions you ride in, what
Stripped down this is what you might find lurking underneath. Left untreated this is the sort of corrosion that will eventually impact on the mechanics and electrics of the bike and spread out to more visible areas.
What should be more obvious now though, is that while you can't do much about the metals used, (short of digging deep in your wallet for more expensive corrosion resistant parts and fittings), or the oxygen present (thank God), the biggest villians of the piece and the ones you can do something about are moisture and the corrosive contaminants and road crud that it absorbs.
A lot of anti-corrosion treatment products are now coming onto the market, some good, some not so good. Applying them properly will often be the difference between whether they work effecively or not. Our own preference is for ACF50, which is why it's at the heart of our Halo Smart Clean treatment process.
Application of ACF-50 by high pressure misting is so effective in combating corrosion because the fine particle mist produced, together with the 'creep' action, deep penetrates and coats every area of the bike, neutralising and killing exisiting corrosion. The thin film coating stays fluid, even getting down into bolt threads,
to actively seek and drive out moisture. Being non water soluble and designed to
polar bond to surfaces makes it resistant to washing off, providing a long term
effective barrier against future corrosion.
Most of us have seen the effects of corrosion, but understanding how it happens is a little more complicated. It has several different forms, and all need an degree in chemistry to understand the process fully.
Well, we're bikers, not scientists, so lets cut it down to basics and get a simplified idea of whats going on and more importantly what we can do to tackle it.
So,
you're asking, if this is such a natural process and can even be put to good use; where's the problem?
Take a bike and ride it around central Australia for a few years. The oxidisation process will still be going on, but it's unlikely you'll find much corrosion on the bike. The same bike in the UK would probably only last a year before the signs of corrosion were seen. What does the UK have that seems to be missing in Australia to cause this? The answer is moisture, ....... and we have it in abundance!
Once moisture, in whatever form, lands on the surface of the metal, the circuit is complete and electrons start flowing. Those areas of our bike have become a mini battery. Electrons are stripped away from the Anode areas, eating through the metal and the byproduct combines with oxygen to produce metal oxide, rust.
How fast or aggressive this corrosion process is depends on a couple of main factors. Firstly, how reactive the chemical makeup of the metals used are. Some metals are very reactive, the most obvious one being mild steel. Others, at the far end of the scale, hardly react at all, titanium, gold, platinum. Manufacturers use this factor to construct alloys that will be resistant to the corrosion process. How effective they are depends on the quality and quantities they use in the mix, how much you pay for these components should, in theory, be a good indication of their quality.
So now you know why winter months and road salt have such a devastating effect on your bike. Hopefully you can also see how this is not just a winter problem. Corrosion goes on throughout the year in varying degrees. If you allow it to get started during the milder periods, then come winter you'll have given it a head start and it'll seek out every weak spot it can find.
Rinsing your bike down reguarly should help remove road crud and salt, preventing it from building up and having more contact time to be absorbed by any moisture present. An occassional wash with a decent shampoo should remove the more stubborn stuff.
After washing get it as dry as you can. Microfiber towels should get the bulk off, a decent bike drier will blow water out of electrics and nooks and crannies. Apply a good quality wax to any paintwork and a water repellent to the rest of the bike. You can't eliminate water coming into contact with the bike, either during riding or when it's stored away, but the better the barrier you can put in place between it and moisture the more effectively you'll shut off that side of the battery circuit and cut off the electron flow that causes corrosion.
