The 28-year-old cyclist, who will contest the mountain-bike cross country event, was one of the last athletes to be named in the Scotland squad when it was finalised earlier this week.
While it raises some questions about the claims made regarding the comprehensive nature of talent identification that goes on in this country, hers is an uplifting tale, reminiscent of a bygone age of derring-do when gifted sportspeople would have a go at events and suddenly find themselves competing among the elite.
Known to be a talented athlete in the Stirling area, MacPhee, who worked part-time in a running shop around a mile from the sportscotland Institute of Sport, was well into her 20s before her decision to find a different way of getting around took her down new roads.
That, in turn, was after originally having come from a part of the country where there had seemed no route down which to pursue a sporting career. "I come from the Outer Hebrides and sport wasn't really something we had lots of access to," she explained, adding that she thinks she is the first woman from that part of the world to compete in a Commonwealth Games.
"So it's never really been a thing to want to be an athlete. Well, I did when I was younger. I thought then that I really wanted to be an athlete but I always thought 'I'm from the islands, I'm never going to be good enough . . . ' "
Having moved to the central belt she then had her first happy accident. "I bought a bike from Recycabike when I was 23 or something. It was too heavy, too big, really old and I just started pedaling. My friend and I entered a triathlon and did okay and I was like, 'this is kind of cool; let's see what happens if I train'," MacPhee recalled.
The organic nature of that sporting development continued to the next stage after she had experienced some success. "I'd been doing triathlon and it wasn't until last April I did a mountain bike race and it went quite well so I thought I'd carry on with that," she said.
"I had raced for GB in off-road triathlon but my swimming . . . islanders are notoriously bad at swimming and I was just never able to progress my swimming enough to do it competitively in an event like the Commonwealth Games. I was always stronger on the bike and run, so it made sense to switch to cycling."
There is an element of under-statement in her observation that it "went quite well" on that first competitive outing. "In April when I did this random race, it was like a Scottish Series race, I came second, beating a girl who was a Commonwealth Games hopeful," she said. "So I thought that if I could beat her and I'm not even a mountain biker then maybe something good can come out of it if I start training. I stopped triathlon in October and just concentrated on the bike and it's taken off."
And how. Backing from her local bike shop, Rock and Road in Bridge of Allan, just across the road from the running shop she used to work in, means her old bike - sold on for a tasty £10 profit - has now been discarded in favour of a high-tech machine worth around £7000, or "about 12 times the value of my car".
"They're fantastic. They supported me when I was doing triathlon and I wouldn't be able to do it without them," she said of that backing, laughing at the memory of having initially pestered the Rock and Road owner for a loan of his bike for those first forays into meaningful competition. "They started supporting me about two years ago. They give me bikes to ride and I've gradually built up that relationship."
Access to sporting nous is also becoming available. "We're off to camp in France with Team GB on Monday and you can imagine what that environment will do to us - Scottish Cycling have put an incredible programme together," said MacPhee, barely able to contain her excitement at the prospect.
Such is the nature of mountain biking, however, that after falling into her sport of choice, MacPhee has also simply fallen. She had been training seriously for little more than a matter of weeks when she was involved in a crash which might have wrecked the confidence of a less spirited individual - MacPhee suffering concussion, while team-mate Charline Joiner sustained spinal fractures.
"We were going quite fast . . . about 50 kilometres an hour, maybe 60," said MacPhee. "Wheels connected and we just crashed. I was at the front and there was a big pile up and I was concussed. I didn't know where I was, or why there was snow on the hills or why I was cycling with my team-mates."
Yet, undaunted, MacPhee demonstrates the mentality required to compete in her sport by expressing not the slightest surprise that Joiner is also in the Scottish team, taking part in the track endurance and road race events. "I know Charline really well and we both have a really positive mindset. I know that would get her through and that she would be fine because there's so much to be said about having that positive frame of mind and knowing that you can overcome it. So I knew . . . I knew she would be fine."
As to her own targets for the weeks ahead, MacPhee is optimistic of a strong showing. "I will be aiming [for] top eight and medaling in 2018."
That seems reasonable enough given her progress so far. Unless, of course, she discovers something she is even better at in the interim.