How to remove rust inside steel frame tubes?

[DiTBho]

Today, I found an old (1992) steel frame in a warehouse.

Apparently it seemed to be in excellent NOS condition, however, when I dismantled the fork and steering group I first found brown grease ... then a large part of the rusty fork steerer tube and finally rust inside the steering tube

Then, looking with a flashlight I saw rust inside the horizontal tube too, and, even worse, dismantling the bottom bracket cups, there is rust there too

Rust inside the tubes: how do you remove it?

[edocaster]

I recently saw this video: https://www.youtube.com/watch?v=fVYZmeReKKY

I've used the formula to derust hub parts, and it seems to work well. Not the best for shiny surface finishes, but seems very effective. Not sure what the effect on paint would be.

And the frame would need to be treated afterwards to avoid new rust forming.

[jimster99]

I only have experience of this from a motorbike, but two possible options for you:

- rag soaked in oil pushed through the frame with a stick then forget about it

- electrolysis (requires a car battery charger and a few other bits and pieces including a bucket big enough to submerge the part, but cheap & 100% effective)

Soaking in acid doesn't really work that well from my experience. Using a wire brush or similar is a bit too fiddly and hard work.

[Carlton green]

No doubt some knowledgeable person will advise me, but I’m puzzled as to why anyone would be particularly concerned about removing internal rust. To an extent internal rust is a protective layer and so long as its presence doesn’t enable structural degradation and failure it’s surely best tolerated. Removing dirt and loose rust seems sensible and - whilst I’ve never felt the need to bother - so does applying treatment (oil, wax, etc.) to stop further rust.

The rust that worries me is external and it does so because the protective layer of paint has gone, external rust needs removal so that replacement paint / protection can be applied. External to the tubes is where the rain, muck and salt comes from and to my estimation those things cause the much bigger rust hazard - but, of course, I could be wrong.

[tim-b]

Something like Fe123 https://www.rust.co.uk/product/fe-123-rust-converter/ or ACF50 https://acf50.co.uk/

It’s important to note that adhesion within the cavity is not crucial, so applying a generous amount of the converter is recommended. However, Fe-123 contains heavy zinc phosphate solids, which can be challenging to atomize during cavity injection.

[peetee]

Don’t forget that rust was once part of a frame. A quality frame will have very little mass that is unnecessary, so, that rust was once something necessary and contributing to its integrity.
Lumps of what was formerly the metal of a bike fork would put me off right away.

[al_yrpal]

I recently did some rust treatment on my old Camper. I found Kurust very good it seemed to stabilise the rust and made it ready for painting. That said I dont think a bit of surface rust inside a frame is in any way dangerous unless it has the appearance of being a crust which would indicate severe weakening corrosion.

Al

[Nearholmer]

^^^

Yes.

If it’s simply a sort of “fine dusting”, not to worry, bu anything a bit crusty, trouble.

The challenge is to know what’s going on inside the small cross-section members, and unless you have an endoscope and access, you can’t.

Assuming all it is is the “fine dusting” sort of rust, one of the treatments mentioned above will help. Personally, I favour waxoyl, sprayed in using a fine tube, with the waxoyl nice and warm (put the can in a nice hot bath for an hour, shaskibg it occasionally). I’ve found it to be incredibly tenacious and effective on the outside of things, where it gets attacked by the weather, let alone the inside.

[Brucey]

rust nearly always looks worse than it is. A surprisingly small amount of iron can create a surprisingly large amount of rust. This is possible because rust is (by volume) mostly oxygen and water.

You can remove loose rust within frames by putting a few ball-bearings inside and then vibrating the frame. This process normally turns loose rust to a powder, easily removed along with the ball bearings. The frame can then be treated internally eg using a little waxoyl. If you are curious about how much metal you have really lost, you can dry what comes out eg. by roasting it with a naked flame. What remains is iron and oxygen; the colour being a good guide to the exact oxidation state of the iron.

[DiTBho]

rust nearly always looks worse than it is. A surprisingly small amount of iron can create a surprisingly large amount of rust. This is possible because rust is (by volume) mostly oxygen and water.

You can remove loose rust within frames by putting a few ball-bearings inside and then vibrating the frame. This process normally turns loose rust to a powder, easily removed along with the ball bearings. The frame can then be treated internally eg using a little waxoyl. If you are curious about how much metal you have really lost, you can dry what comes out eg. by roasting it with a naked flame. What remains is iron and oxygen; the colour being a good guide to the exact oxidation state of the iron.

I can do this in the head tube, but what about the rust inside the horizontal tube?

How do I know there is a lot of rust? well ...

• fact#1 - the junction between the horizontal tube and the head tube has a hole and by pointing a LED light I see rust
• fact#2 - the rear brake wire sheath passes inside the horizontal tube, extracting the sheath, which is plastic, it is all rust colored, a sign that there is a lot of rust inside the tube

I don't understand what the hell they did to this frame ...

[rareposter]

I don't understand what the hell they did to this frame ...

It doesn't take much rust, especially when combined with a bit of grease to spread it around, to look like a LOT of rust.

Best way of removing it entirely is electrolysis but that requires a "bath" big enough to immerse the frame and although it's actually not that difficult a process, it does require a fair chunk of space when doing it to a bike frame.

[Brucey]

it is normally possible to add a hole between the seat tube and the top tube, without wrecking either the frame or the paint job. Frames where the rear brake cable is hidden inside the top tube are very good at letting water in and then holding it, so rust is a very common problem. It is unusual for it to be a problem on an unused frame though.

[Brucey]

it should be possible to clean the inside of the frame tubes via electrolysis if you put the solution inside the frame, in which case no tank is required; all you need to do is to stop the leaks.

[NickJP]

I would just spray some corrosion inhibitor inside the frame tubes and leave it at that. CRC make a lanolin-based spray product, though it might be a bit thick to get it everywhere inside. Boeshield T-9 spray is much runnier, and I've used that without problem to protect the inside of steel frames. I spray in copious quantities, and rotate the frame around to get the stuff to run everywhere inside, then set the frame on newspaper at various angles to allow the excess to drain out.

Do the procedure somewhere where the drips aren't going to cause a problem.

[DiTBho]

Interesting topic here