Rust spot?
 

Just noticed this spot on the bottom of my chainstay-

http://i23.photobucket.com/albums/b3.../smallrust.jpg

It is completely beneath the finish of the bike, but it sort of looks suspicious. Anyone seen anything like this before? I don't want the chainstay to disintegrate while I'm riding it.

hmmm...

http://pds.jpl.nasa.gov/planets/imag...ter/febgrs.jpg

That, my friend, does not look even remotely like a "disintegration" danger.

Is your bike steel?

If it's aluminum, then that's not rust...that's a flaw of some kind in the paint.

If it's steel, that's still not anything to worry about, but if it makes you feel better take your bike apart and hose some frame-saver through the inside of the frame. It's corrosion protectant.

heh, yeah, it's steel. Maybe I'm being a little obsessive about checking it out, but I'm also obsessive about not getting my teeth knocked out / eye sockets broken, etc.

It was not there when I bought the bike (about 1.5 years ago), but has appeared during the past 6 weeks...which I thought was wierd. Combine with no disturbance of the paint finish, and the fact that it looks like it's beneath the base coat, and it's enough to get my imagination going.

Perhaps look at hitting it up with some frame-saver then.

That spot is really really tiny, and doesn't look (at least to me) very dangerous at all.

I don't think you have any problems.

why dont you poke it, and if the poking device breaks through the stay then you know it rusted from the inside. If it doesn't then maybe its a stain from roomates trashbags. VEGAS!

Keep an eye on it, if it changes in size, color, or shape, get it checked by a dermatologist, could be skin cancer.

;)



Rust (even from inside) would almost certainly disturb the smoothness of the finish if it became a visible mark. I'd suspect a paint defect of some sort. Are you certain it doesn't wash off? It could be you ran over some oil/solvent/etc that splashed up and discolored the finish.

The easy way to be sure would be scrape the paint off down to bare metal, find out what it is, and repaint. However if you're the kinda guy who NOTICED a spot that small on the bottom of your chainstay, you're probably sensitive about the finish and wouldn't want a ghetto-looking paint job.