Bicycle Mechanics - Will Aluminium rust?

As above, if so what kind of conditions would accel or deccel the process? How can i maintain the frame or know how to check for rust?

NO, only steel will rust, but AL does corrode. However neither is likely to happen unless you don't take care of your bike.

Yahoooooo... thanks dude!

NO, only steel will rust, but AL does corrode. However neither is likely to happen unless you don't take care of your bike.



mmmmm... I agree & disagree...

Steel: Will rust in a matter of SECONDS... ever wash an engine block in a parts washer, and take an air-nozzle off a compressor to it? It turns to rust in a matter of SECONDS.

Alumimum: Will *not* rust, but will Oxodize. It resembles "chalky powder" that comes off it. Oxidizing aluminum only occurs from things IN the water, salt, or things like that. Straight (pure) water won't oxodize water (to my knowledge). Case in point? Don't ride your expensive AL framed bikes in the salty roads in the winter while there's slush on the ground... and you'll be ok.


-Matt

I just threw my bike in the dungeon. No more daylight till spring :D

Plain aluminum will slowly oxidize (that *IS* rust in terms of aluminum) when exposed to normal conditions.

Typocally that is why aluminum tends to be gray in color instead of silver. Polished and coated AL or ANODIZED AL does not corrode much...

Similar to rust on steel, the oxidation protects the AL. Unlike AL steel may continue to rust in a mosture rich environment because iron's rust flakes and exposes new metal that begins to rust.

AL is more like copper in that the corrosion protects the AL from "rusting" further... Unless it is of course scratched...

Anodized is actually a special method of kinda "pre-oxidizing" the AL to protect it :)

As above, if so what kind of conditions would accel or deccel the process? How can i maintain the frame or know how to check for rust?

AL does oxidize not corrode as I said but I was lost for the correct word at the time. Steel can rust within seconds if bare and untreated and under right conditions. BUT you can prevent rust from occuring inside a steel frame by applying Boeshield T-9; if you have a new steel frame and are concerned about the rust issue then this will help you sleep at night better. You would of course have to remove everything off the frame so you can spray the stuff inside-kinda a hassle huh? If you have an older frame and wish to see if rust has started you can remove the seat post and look down with a flashlight to see if you see rust on the tubing but especially the bottom bracket area because that's where moisture will settle.

But please note something. I have an old 79 Schwinn Traveller (steel frame) that I used as an beater bike when I was in my early 20's that I bought new. I lived along the Southern CA coast (Santa Barbara) and parked this bike outside of my apartment where it got rained on for at least 8 years, I also rode it on the beach thus exposing it to salt water. I never really took care of this bike and for the last 8 years has sat in disrepair in the garage. There is some light surface rust where the paint was scratched. I stripped down the frame about a 2 months ago and found light rusting going on inside, but nothing that would make in unrideable. My main bike (the frame) was bought new in 84, this bike I took care of it and kept in the garage, there is no rust anywhere on it or in it. NONE of these bikes were treated with any rust treatments. I think the newer frame may have been treated with zinc which is the same thing that car manufactures do to prevent rust, but not sure about the zinc, but when ever it got a little scratched it never would rust. Of course I do, and you need to too, is touch up any scratches with touch up paint as soon as you notice it.

Look, steel is not going to rust away to pile of dust before your eyes. Sheldon Brown sometimes rides on an old steel bike made in the early 1900's probably made of cheap old gas piping with no rust issues even concerning him. I seen junked steel frames in junkyards that sat in all sorts of weather for eons and their still there-rusting sure, but not rusted away.

You will either wear out your frame or get bored with it or die long before it succombs to rust.

mmmmm... I agree & disagree...

Steel: Will rust in a matter of SECONDS... ever wash an engine block in a parts washer, and take an air-nozzle off a compressor to it? It turns to rust in a matter of SECONDS.

Alumimum: Will *not* rust, but will Oxodize. It resembles "chalky powder" that comes off it. Oxidizing aluminum only occurs from things IN the water, salt, or things like that. Straight (pure) water won't oxodize water (to my knowledge). Case in point? Don't ride your expensive AL framed bikes in the salty roads in the winter while there's slush on the ground... and you'll be ok.


-Matt

Your word oxodize is correct, I used corrode because at the time I was lost for the right word. Engine blocks that rust (technically rust is also oxodation) are made of cast iron; cast iron is very susceptable to rust whereas cromoly steel is not as susceptable. But even a cast iron block will not rust away to a pile of dust, just go into any junk yard and you will find this to be true. The Golden Gate Bridge as well as many others is constructed of iron and was built in the early 1900's and exposed to salt water constantly and it's still there and totally safe to drive for at least the next 100 years.

Your word oxodize is correct

Actually... the right word is oxidize, haha, were you guys affected by my nick and thus came up with oxodize?

Nothing helps protect the exterior of all finishes like a good coat of wax. And oxidize is correct in all cases. Generally speaking, the oxidation of aluminum is 'tougher' and less porous than that of steel. The end result is that aluminum oxidizes less quickly. Anodization is an oxidation process (as stated above) with aluminum that puts down a very 'tough' and non-porous oxide film that greatly reduces any further oxidation. Pretty nifty processes that even comes in colors. Some later steels have been alloyed to rust with a 'tough' and less porous film. A good example is some of the newer modern art structures that are rusty on the surface. Most structural steels are now alloyed in such a manner. However, to the best of my knowledge, no bike tubing has been alloyed with this in mind. The newest steels for high-end bikes are being protected before they leave the factory by some sort of internal treatment. My '02 Scapin has such a treatment, but all are calling it proprietary, so I don't know what it is. Am guessing that it is a quick electrolysis with Ni coating. Other than that, using Frame Saver or the previously mentioned Boeshield T-9 are great internal insurance along with wax on the outside (I really drown the internals on my frames). You should do so even if you put your baby into your damp celler (unless you are running a dehumidifier at the lowest setting) for the winter.

I agree with ParamountScapin. I found a little more detail on the Scapin corrosion protection process. The process is not verified, but it sounds correct: "All of their frames are internally varnished, observing strict criteria in the safeguard of the environment. The first in the world to introduce a special anti-corrosion treatment called A.W.P., a protective treatment whose aim is to make the steel frames resistant with time to corrosion and to rust, externally and internally. A.W.P. (All Weather Proof) is in reality a triple process composed of zinc-nickel plating, phosphoric treatment and finally of a "black electrophoresis"."

The Golden Gate Bridge as well as many others is constructed of iron and was built in the early 1900's and exposed to salt water constantly and it's still there

Nope. The Golden Gate Bridge is made of steel, not iron. It was also made in the 1930's, not the 1900's. Please check your facts.

One could argue that anything before 1950 would constitute "early 1900's" and 1951 through 1999 would be "late 1900's".

That said, I would call the 1930's late-early or early-mid myself.

I hope that this post makes sense because I want to viewed as intelligent and thoughtful... it's important to my self-esteem.

:)

Nope. The Golden Gate Bridge is made of steel, not iron. It was also made in the 1930's, not the 1900's. Please check your facts.

Read my post again I said early 1900's and 1930 qualifies, since the mid 1900's would have been 1940 to 1960; and if you really want to be picky it was 1933.

Regardless if steel or iron, the point is it still hasn't rusted away.

I agree w/ froze about steel rusting. I've seen many rusty steel bikes, but never one that was completely rusted to dust. Not that it's impossible, but rust on mild steel and better usually seems superficial at worst. I had similar experience w/ my steel MTB in Venice, CA over the 8 years I lived there. Was parked outside all the time, rain, shine, or fog. All the scratched up/bare steel rusted. It may have been worse if I lived closer to where the ocean spray could contact all the time.

I recently decided to clean up the bike and found all those nasty rusted spots on the frame cleaned up quite well using WD-40 on a Scotch brite pad. They even buffed up well with tripoli on a flannel rag.

The bigger problem is with steel screws/nuts/threads. When they rust, they can, for all intents and purposes, freeze up solid. A nice thin coat of grease can prevent much of this.

I've never heard of serious problems with aluminum oxidizing, within reason. It tends to just "get ugly" IMO. If it were bad enough that corrosion takes place, you'd probably notice it quickly.

reading though this reminds me of my materials engineering classes i took when i was still in college when the professor would differentiate corrossion, oxidation, etc.... :) and everyone would just nod.. I'm happy some of you listened. :D

This is why bikeforums is the best forum for me...I'm always glad to see so much intelligent content.

keep in mind the aluminum used in bike frames isn't pure al, it's an al based alloy, 2024t3, 6061t6, or 7005 are the most common alloys used in bike tubing. pure Al oxidizes to form Al2O3 which is "nonporous" so it acts as a protective layer to further oxidation. anodizing protects Al surface also due to use of sacrificial anode to "plate" onto bare Al surface.

steel is Fe-C or Fe3C system so technically it kind of is iron. a Fe-C system with >0.4% carbon content classifies technically as cast iron, though... but anyway the rate of chemical attack in all materials is affected not only by material composition but also by physical condition like scratches, fractures...

btw does anyone know if steel bike frames are galvanized to prevent corrosion? or is the paint the only obstacle between the metal surface and the air?

Regardless if steel or iron, the point is it still hasn't rusted away

That's why the constantly paint it.

tFUnK - Better steel frames get a high quality primer before the paint. Often applied with a electric charge which makes for a better coat. As you can read above, some folks (Scapin and others) are doing some interior plating which puts down a a micron or so of a metal like Ni, which has a very tough and non-porous oxide and protects the steel from rusting. Galvanizing is heavy, so other methods are used.

Dave Stohler - Lighten up, man. You'll feel better about things when you're back to work.

That's why the constantly paint it.


That's right Dave!!! And that's why we need to be sure we touch up scratches with paint and keep our bikes cleaned, waxed and lubed. Thats why my 20 year old steel bike has no rust anywhere.