Hey fellas,

I have an '85 Trek 510 with some wrinkled paint on the top tube. Upon further investigation I realized it is rust forming underneath the paint. I scraped a bit away with a flathead and it did reveal fresh steel. The rust was about as thin as the layer of paint.

Is this still safe to ride?

Filiform corrosion generally will not affect the structural integrity of the frame. Usually it is a direct effect of the owner (or PO) failing to care for their bike: at least toweling off the sweat they've rained down upon the frame. Sometimes it can be the result of bad paint, or paint job as well.

Pull the seat tube and check for internal corrosion; always a good idea in any case...

But don't sweat the surface stuff. Treat it, maintain your bicycle, and ride on.

(Oh, and pics don't show, for me anyway. Please try again. We appreciate pics. Pics are worth many words. I wish I had a pic to express how many...)

The pictures aren't working.

Oopsie, the images didn't show up... let's try it again.





The seat tube looks okay for the most part as well. Maybe some more surface rust on the inside but not a whole lot. How does this look? (there's a bit more about midway down but I couldn't get my camera to focus)



I also didn't notice this before but there is a seam on the backside of the seat tube, which I'm assuming is for the tightening screw. Is this correct? It just looks a little rough so I thought I'd ask.




Thanks for your help!

Your photos show filiform corrosion. Seat tube looks relatively free of rust, if some of the brown is grease as I suspect.

I'll leave evaluation of the seat tube cinch area to more those more learned in frame building.

(I will note, however, that closeups of corrosion gives me the willies; rather too much like looking too close in the mirror in the morning, or using one of those magnifying mirrors... Ack.)

That sums up what I was feeling while looking closely at this. Also not sure how I feel about knowing these could be caused by the previous owner's sweat. But I hope this is the worst of it. There are no other filiform corrosion anywhere else, just paint chips and scuffs all around.

How should I treat this? Just sand off the rust and paint? I have some black enamel automotive paint that I was thinking of brushing into those spots and wet sanding to make uniform.

I really appreciate your feedback!

That slit in the seat tube is meant to be there and just neeeds a clean, jam a rag in the seat tube first to stop any crud contaminating the bottom bracket

I personally would not worry too much about the rust, it can get a lot worse but will really take some time, remember the bike is only original once, people demonise rust and while it is bad it will be a long time before it compromises the integrity of the frames structure.
If you want to see bad rust have a look at some of the other threads, my thread on my 1958 Jacques Anquetil, which is further down the page, enjoy the bike mate.

Filiform corrosion isn't really progressive, unless the original precipitating ingredients are still present. You can sand it down and attempt to match the paint. On the hand, you have photos of its current state and can monitor its status, which is what I would suggest.

There is a way that seems to work for infiltrating the "spider veins" of filiform corrosion, but it is very involved, and I'm not sure it works any better than keeping the sweat off the bike.

I use clear nail polish or clear coat to keep the paint chips and such from rusting. A good synthetic wax can work for a while too. (My Allez is an exception (for me). It has a "matte/satin" finish which is not to be waxed, so I match it with a 80% flat, 20% gloss mix of black auto touch up paint, after priming. <sigh emoticon>) Matching paint colour rarely seems to work, though there are those on BF whose work is stunningly impressive.

(I blame auto-correct for "filo". That, and my appreciation for Greek food... I am rather peckish.)

The exterior rust isn't bad. On the 2nd pic, I'd clean it up with a scratch pen and put some black touch up on it.

Awesome. Thanks all!

My bottom bracket socket came in the mail today (just in time!) and I was able to remove and inspect the frame in that spot. Looks like a bit of surface rust (similar to seat tube) and nothing major.

One last question! Is it too late to think about applying frame saver at this stage? I would need to buy it but not sure if it's worth it.

I do have some motorcycle chain lube/wax spray that I can possibly use. I saw something like that being mentioned elsewhere on the web.

It is not too late to apply an interior coating to your frame, if that's what you choose to do. Their is no clear consensus on whether it is necessary, and my personal experience is inconclusive. I live 500 feet from the ocean, and I've treated some of my bikes and haven't treated others. (However, I should note I flush the tubes of my bikes with phosphoric acid when I acquire them, and that does leave a corrosion resistant coating, so they sort of are "treated", though not in the same sense as you mention. So far, no internal corrosion on the "untreated". Your experience may differ.) It can't really do any harm?

As an aside, the "treatment" I've been using is a new product of the WD-40 company which antique gun aficionados have been touting: "WD-40 Specialist Long-Term Corrosion Inhibitor." It's inexpensive as it's new. (I am not affiliated with WD-40, nor compensated.)

I think that might be the ticket for me. Thanks for the tip!