Originally Posted by
ClydeClydeson
That's a 'NO'. Sorry,
JasonJas . ANy weld repair will not be as strong as the original, which was already not strong enough.
THis was likely caused by a too-short seatpost, though. Seatposts have a 'minimum insertion' mark, but I am never sure if the seatpost is designed for the mark to be at the top of an unsupported extension on top of the seat tube, or if it is better to make sure the mark is down near the tube junction where there is support.
Your “NO” is far too hard. A weld at the crack would hold up for a while but the problem isn’t the weld but the lack of annealing the frame afterwards. It could be welded to get you down the road but it’s not a long term fix.
As for the break being caused by the seatpost not being inserted far enough, that’s a possibility but I broke a frame in a similar place because I was using a very long set back seatpost. The post was inserted far enough into the frame but the setback cause too much stress above the frame junction. The seat stays on the bike came in a lot lower than this frame, however.
Originally Posted by
ClydeClydeson
Also, welding will deform the seat tube and it may make the seatpost fit unreliable.
A competent welder should cause any kind of deformation of the tube when welding. Heat transfer for MIG welding is relatively localized.
Just to be clear, I probably wouldn’t try to fix the frame for years of riding but as a short term fix, it’s viable. It’s probably not worth the cost of the fix, however. Frames are fairly cheap.