Elite mountain bike riders Emma Viotto (2:15:29) and Brendan Johnston (2:42:40) - who both ride for mountain biking team Trek Shimano - blitzed the competition early on Saturday.

Viotto finished second in the stage two kermesse behind Ruby Livingstone while Sean Whitfield claimed bragging rights in the second stage of the men's event.

Cancer survivor Johnston doesn't compete in cycling too often barring "the odd race here and there" and he couldn't be happier a window opened up for him to tackle the National Capital Tour this weekend.

"It's usually clashed with mountain bike events in the past but this year it hasn't," Johnston said.

"Many years ago I wouldn't miss it at all so now that I had a free weekend I got stuck in and had a race. It's paid off.

"I knew I was in pretty good shape, the mountain bike season is underway at the moment so the form crosses over pretty well."

Johnston was riding by himself with no teammates and soon found company in another one-man band in Attaque Gusto's Ben Hill.

The pair broke away from the pack before Johnston launched into the climb and never looked back, before going on to finish fourth in stage two.

Canberra Cycling Club's Viotto overcame a bout of illness to pip Roues Chaudes rider Erin Nolan and claim the spoils in the first stage of the women's event.

While she was feeling below the weather, Viotto never even entertained the thought of pulling out of the biggest event in Canberra cycling.

"I haven't been feeling the best lately, I've been battling a bit of sickness over the last few weeks so I had no expectations," Viotto said.

"As soon as we started riding I felt good. It was pretty windy and I like the wind because it makes it hard for everyone. I was lucky enough to get away on the climb.

"I would never pull out of a race unless I physically was going to be sick. I tend to ride mountain bikes, I come from a mountain bike background, so I just had to finish the race.

"I was lucky enough that the legs felt good and I just had to keep the pace going."

Viotto will back up again for the stage three criterium event on Sunday buoyed by the confidence of a bumper opening day.

"It's good, we had a good bunch of ladies. We had about 25 female riders, it's good to see so many women here racing, it's good for the sport," Viotto said.

"It's been fantastic. It was quite exciting, Brendan Johnston took out the A grade men's, I ride on the same team as him for mountain biking. I was pretty happy for him."

Stage three gets underway at 9am at Stromlo Forest Park on Sunday.