Hayne attracted interest from two other NFL clubs, the Detroit Lions and Seattle Seahawks.
He said he thought until very recently that he would be going to the Lions - "It was very close but it wasn't to be."
He was attracted to the 49ers because their new head coach Jim Tomsula had a good knowledge of rugby from his time coaching in the NFL's European feeder competition and so understood the transition he had to make.
"For me this [deal] is a small step in the right direction," said Hayne. "The hard stuff starts now."
Hayne attracted interest from two other NFL clubs, the Detroit Lions and Seattle Seahawks. He said he thought until very recently that he would be going to the Lions - "It was very close but it wasn't to be".
Hayne said he initially rejected the possibility of doing a work out for the 49ers.
"They were about to lose their head coach [Jim Harbaugh] from all media reports and the plan was to go to a stable environment.
"There were was a lot of question marks, but I said I'd go. I ended up meeting Jim Tomsula the current head coach, and we spent about an hour together.
"He was the one coach who knew the transition better than anyone and knew what it was going to take for me to make the transition.
"When Jim [Harbaugh] left and Tomsula got the job, the one guy I spent the most time with was the new head coach."
- AAP