So I have a 2006 Dahon folding bike with a 4130 steel frame, and two days ago I noticed a small crack on the seat tube, just under the clamp. I'm not the original owner, so there's no warranty to work with. I've taken two photos (one with flash, one without).
I've marked the end of the crack with a Sharpie to determine the rate of crack growth, and while there's been no change since I noticed it, and I don't know how long it's been there, I assume it is going to get worse with time, and that I should take steps to get it repaired early.
So I'm here posting on Framebuilders to confirm that such a crack is indeed repairable, and perhaps to get a reference to someone in the Los Angeles/Orange County area who might do a quality repair, and maybe to get a sense of the costs I'm looking at (and I don't really care how it looks - this is my daily commuter bike.)