MN_Runner":2luagjxh said:
More I study the frame design and look at the stress load, the elevated rear chain stay design is flawed and doomed. Perhaps it was an interesting idea and aesthetically pleasing but the design flaw was neither understood nor suspected. I have not seen this elevated chain stay design until today. There must be more owners of Alpinestars Ti bikes out there. It is a beautiful bike perhaps meant to be in a bike museum.
The e-stay as a concept is not flawed or doomed. The stress load is higher than a conventional double-diamond frame, but an e-stay can handle it if designed properly. Alpinestars (literally) came to within a few inches of perfecting the whole e-stay design. If they had let the lower tubes connect to the dropout area instead of welding them onto the seatstays, it would have been perfect.
That being said, This particular one was a flawed design indeed. The triangle is good enough, but the little bit of tube they left sticking out is the bit that's taking most of the stress. This is a classic problem with Alpinestars e-stays, and the only reason why I haven't bought one myself.
So basically : IMO this is not a courier-related problem. It's plain and simple fatigue.
You could have it welded if you find a frame specialist who also works with Ti, but even then the bike would become a garage queen or for casual asphalt use.