Originally Posted by 79pmooney

I'd bet the seattube will have to be reamed after welding to get good seatpost fit even if the weld does not go all the way through. (Distortion due to the heat.) If this welder isn't a framebuilder he probably does not have the appropriate reamer. A regular steel and softer metals bike mechanic might be unwilling to sacrifice his tools on the much harder titanium. I'd call a titanium framebuilder and ask his advice. Or just get it welded and try the seatpost. That crack is close enough to the the top of the seattube that the inside is accessible and visible so careful hand filing should work. Not recommended but there are probably more than a few steel frames out there with the same treatment.