Hello all!

I will start working on my Crescent branded Motobecane (I believe Team Champion).
It has a crack-bulge beneath the seat tube slot. The crack (or maybe slot cut too long??) goes straight down, on the inside I can feel a shallow longish bulge to the outside.

I think the frame is not suitable for all-out hard cycling, but quite safe for casual riding, no?

The things I am not sure:
- could it be a manufacturing fault- the slot cut too long? (the relieve hole is not in center, but probably unrelated)
- another possibility: water freezed in the seat post flute and caused bulge (the seat post is not fluted, but I am not sure if it is original).
- will extra long seat post help to distribute stresses more evenly?