I recently got myself an 83 fuji opusIII frame, chromoly, to build up and use as an extra awesome neighborhood running sort of bike. It's got some paint missing here and there, with some smallish rust spots, and a little heavier rust starting to show up inside the tubes. My question is - how quickly is this going to grow and destroy the frame? I live in a tiny studio apartment, so effecting the oxalic acid treatment would be a super major hassle, and I'm pretty low on funds from buying other parts, so finding and paying a shop to de-rust is problematic. And even though I'm hardly building it up to be a show bike, I'm putting money and effort and whatnot into this bike, and plus, I'm already pretty attached to the frame and don't want it to die any time soon. So, is it okay to leave the frame as it is for now, ride the bike, and then maybe get the rust taken care of in the spring? or am I building myself a death trap?

lots of little spots like this one. sorry for the supermassive cellphone pic.


thanks!

Highly doubtful you would find a shop to treat rust. Your best bet is to find someone that is treating other bikes, to share in the oxalic tub. Rust on the inside of the tubing could be pretty serious. External rust can be treated cheaply with a rust converter product: Walmart sells one for $6, just paint it on.

If you want the bike to last, then you will need to address the rust. May be best off scouting for another bike, one without rust issues, then selling your current bike as a project. Or find a bike co-op in your area.

Project bikes are best suited for people that have the time, tools, space, etc., to work on it.

The Opus III was a pretty high end bike. This unfortunately also means the tubing will be pretty thin to begin with.

You can pour the oxalic acid solution into the tubes after sealing up weep holes, bottom bracket, etc. It has been suggested before that very large garbage bags could act as the container for the frame. I'd try this outside or in the tub in case of leaks. Double or triple up the bags for added security.

The only shop I know that would derust the inside of a frame would be a plating shop. They could soak it in the alkaline bath. But it would have to have the paint removed and cleaned first before they'd do it.

If you are handling the acid directly (pouring it into frame tubes), be sure to dilute it a lot first!

Oxalic Acid works like magic to remove rust, but it does nothing to stop or slow down the process. So, if your worry is that your bike will continue to rust and become comprimised, then this is the wrong solution. Think of oxalic acid as a cosmetic solution.

If you want to lengthen the life span of your frame, you can just leave the rust in there and douse it completely with something that might do something to keep some air and water from reacting with the steel. Framesaver, of course, is made for this. Even WD-40 seems like it would do something.

jim