Leov won the Highland Park event in New Hampshire after qualifying in fifth place.
A scorching final run saw him take the victory by more than a second, overcoming the hindrance of the finger which he injured while racing the previous weekend.
He did not believe it was broken and simply taped it up and hoped for the best.
But it emerged after he had won the race that the finger was broken.
Leov is now on his way back to New Zealand for some time out before heading to Europe for some World Cup events.
But it will be the final time he will head overseas as a competitive cyclist, as he will quit the world stage at the end of the year.
His mother Nola said Leov still very much enjoyed the sport but it was very competitive and he wished to do other things in his life.
A lot of younger riders were coming along and competition was becoming very intense, she said. Leov had to train upwards of four hours a day, and that was becoming harder and harder to do.
He was married earlier this year, and priorities had changed for him, she said.
He will be 28 in October, and though his bike sponsor Trek, was keen for him to continue, he decided he wanted to stop at an international level. He would most probably keep biking in New Zealand in the summer.
Downhill mountain biking is not an Olympic event.
Leov had started a building apprenticeship and was looking to complete this once he retired from the bike.
He will be based in Christchurch and has an apprenticeship arranged.
