Not yet but I have been mulling in my head having a go at the whole ‘warranty is for the first owner only’, given half a chance. The only excuse one major manufactuer could give me for this morally bankrupt practice is ‘well everyone else does it’.
The 1 or 2 yr thing is a nonsense. Warranties given with the sale are firs a marketing ploy to enhance consumer confidence in a product and promote sales, and second used as scam to try and con you that the warranty is limited only to that.
You have statutory rights protection for upto 6 years after purchase, depending on what is a reasonable period. Any manufacturer / retailer warranty is additional, if it conflicts with your statutory rights just screw it up and chuck it in their face.
As there is no restriction I know of to the original purchaser assigning their rights in the original sales contract, I dont see any legal reason why a second owner doesnt in practice have the same statutory warranty rights. After all, the manufacturer is advertising a frame with a given declaration of quality. So, if a frame has a lifetime warranty at purchase then what do you think is a reasonable warranty period for that frame to be implied by statute?
I would have though commencement of a small claims court action for enforcement of the warranty, then blanket advertisement of the fact on forums etc, would have the desired effect. I mean, would you as a manufacturer want to risk a declaration in even the lowest court that your ‘original purchaser’ only condition is unenforceable, and then significant advertisement of this fact?
EDIT: To actually answer the OP. the 1yr/2yr warranty is a red herring. Depends on your actual circumstances (is this the 3rd replacement) but crack after 18m without an intervening cause definitely needs to be repalaced – and if they keep cracking then demand money back as being of unsatisfactory quality for the purpose it is designed for