The Mysterious 10th Bearer.

[Boromir88]

We know flat out 9 bearers of the ring, Sauron, Isildur, Deagol, Smeagol, Bilbo, Frodo, Gandalf, Tom Bombadil, and Sam. But who is the mysterious 10th bearer, who changed the chain, the ring was on, in Rivendell? When Frodo wakes he notices a new chain on the ring. So who changed this? Whoever did could have been the 10th bearer, or maybe there is no 10th bearer, maybe a previous bearer (Bilbo or Gandalf), or soon to be bearer (Sam) did it.

The Shadow of the past quotes "The ring was in Frodo's pocket, connected by a chain, hanging from his belt." Then in Rivendell there is a new chain around it.

Here is my take on things.

First off, it would have to be somebody who knew Frodo had the ring (Gandalf, Elrond, Sam, Merry, Pippin, and Bilbo). 2nd I doubt Gandalf or Elrond would bear the ring themselves, or allow anyone else to touch or even look at the ring. So in my opinion they are not a possibility. Then could it have been Bilbo? Would make sense, Bilbo knew Frodo had the ring, and he was one of the 4 people to actually visit Frodo (Gandalf, Elrond, Sam, and Bilbo). I would think however if Bilbo saw the ring, he would take it, and to give it up, it would take some prodding from Gandalf. In a situation like that I would think would have been recorded and documented so I don't think Bilbo. Leaves us Sam here, Sam is definately a high possibility since possibly if Gandalf and Elrond couldn't watch all the time, Sam was there watching Frodo he very well could have changed the chain. Two other possibilities were Merry and Pippin, them curious little hobbits, knew Frodo had the ring, but was never said whether they visited him or not. Or maybe a random elf over heard about the Ring and gave Frodo a new chain. Maybe an Elven-smith crafted Frodo a new chain and changed it, but being from Aule, and being craftspeople they would have probably been deeply seduced by the ring. There are an endless amount of possibilities so have it.