Hayes' lawyer Mark Sturm said it was a sombre day for his client who was extremely remorseful.
He said his client was over-confident on the stretch of road, which he had ridden many times before, and cut the corner not expecting anyone to come the other way.
"The victim has paid for that with his life."
Aretz was a German national living in Auckland and employed by BM Workshop, an independent BMW repairer.
Judge Kim Saunders accepted Hayes knew the road well. She had been assisted in her sentencing by Aretz's GoPro camera which was affixed to his helmet.
"This was not a persistent case of bad driving but a one-off case of bad driving where you showed poor judgment with tragic consequences. Daniel's death could have been avoided."
She accepted Hayes' remorse was genuine and was pleased that although a restorative justice conference couldn't go ahead because of a language barrier, he had recorded a video apology to be sent to Aretz's parents in Germany.
Judge Saunders said Aretz's parents were struggling with their son's death, which had scarred them mentally and physically.
"The accident is never far from their minds and it is difficult to find inner peace. [Aretz] is buried in Germany and they visit his grave often."
She also acknowledged his parents' forgiving nature.
"What I find particularly telling about Daniel's parents is the acknowledgement that despite their pain and tears they cannot begin to imagine the nightmare that you yourself have been through.
"There are no winners in a situation such as this, Mr Hayes. The tragic consequence, I'm sure, is something that you will have to live with for the rest of your life."
Hayes was also disqualified from driving for two years and six months.