McMains was born in New Hampshire in the United States before growing up in New Zealand on Waiheke Island.[2][3] He attended Kadimah College in Auckland, having to take the boat to school every day.[2] He returned to the U.S. at age 11 when his family moved to Santa Barbara. There he went to Santa Barbara High School. After high school, he returned to New Zealand and got a job working with the New Zealand Breakers organisation in 2007. A year or so later, he returned to the U.S. and started in player development, working with a mix of pro players in Los Angeles. That led to an opportunity to work with players in Latvia, France, and China. He also ran NBA Pre-Draft Preparation for two years in Santa Barbara, while also running off-season workouts for a selection of NBA and international players.[2] During this time, he studied at Santa Monica College (2008–10) and John Cabot University (2011) in Rome, Italy.[4] He was exposed to European basketball while in Rome.[2]
In August 2019, McMains was appointed an assistant coach with Melbourne United of the Australian NBL.[9] He parted ways with Melbourne in August 2020.[10]
^"DRAGIĆEV TRENER: Navija za Slovenijo in Novo Zelandijo". kosarka.si (in Slovenian). 29 August 2014. Retrieved 7 August 2019. I was born in New Hampshire, grew up in New Zealand, attended high school in Santa Barbara and went to the University of Rome.
^"Ross McMains". kiwihoopers.com. Retrieved 21 December 2022.