Originally Posted by
sweeks
This looks like a weld defect, but probably not one that is leading to failure, for two reasons. First, most of the published images of the frames that broke showed evidence of corrosion at the lowest part of the joint. This suggests that the cracks started there, where the tensile stress is greatest, and propagated upward until the remaining weld could not support the load. There was one image on the Tern Forum of a small fracture line at the bottom of the joint, which is what would be expected; unfortunately, this was probably the last place anyone would look.
Secondly, there is paint *over* the defect, suggesting it was applied over an existing crack and also hasn't progressed since. I wonder why it wasn't picked up during inspection at the factory though.
Steve
I would disagree about not leading to failure but see what you mean about existing paint. If the frame was supplied bare or primed to Tern who do the final paint finish I guess while processing the crack could have appeared and then the final paint coat hid the crack from view slightly. I'm amazed that this crack wasn't picked up at the Tern factory that did final assembly. I don't think it would have been repainted since leaving the factory. My opinion was that Dahon and Tern were about equal quality but the more I read the more I put Tern not just below Dahon but much worse than many of the smaller folding bike companies of China who churn out low numbers of bikes. Of course they may have improved dramatically more recently but I have that feeling that you get when you simply don't trust a manufacturer. My perceived quality of Tern bikes is now very low. If I see a Tern rider I think instead of being impressed by their stylish bike I'd more likely feel sorry for them wondering if they will end up under an articulated lorry if the frame breaks. I realise this may not be fair and statistically unlikely but by what I've seen is certainly more true of Tern than any other brand.