Cycling down Dublin’s Rathgar Road in morning rush hour traffic is a bitch. Healthy and tanned today, she has come to bicycle grief on three occasions.

In her gym shoes and standing over 6ft 1 in she rubs the bridge of her nose, the injured zone of her most serious road spill.

“There’s a little bump,” she says. “Hit a parked car that time.”

Routine is a gym in town first thing before afternoon sailing in a three-times-a -day training regime. To the non-sailors in Ireland, Murphy may be the only name in the sport they recognise.

“It was gushing blood,” she says cheerily, pushing her nose sideways to its crash position. “I said ‘call my mum, she’ll pick me up’. My bike was broke in half. But a man called an ambulance. Mortified . ..”

The anecdote is instructive. Dismissive of the broken nose, the fuss of an ambulance is magnified – all of it mortification to the self sufficient and pragmatic. As a solo sailor you get things done by yourself.

Fourth place in London 2012 has also taught her resilience. But the blow of four first places to falling off an Olympic podium finish never closed her down. Hers is a life view that emptying heart and soul is worth celebrating. But fourth in the Olympics – it was not without pain.

“I’ll always look back on that and feel horrified,” she says. “But I said to the performance manager James O’Callaghan before London, I wished I’d had another year’s experience before going into these Olympics. I just feel like I wasn’t quite ready for them. I was 22.

“I was upset. Then it was a happy moment, a really brilliant evening. It wasn’t sad at all. We were in this pub in Weymouth and everyone had Irish flags. Some local guy came up and said ‘did you win the gold?’I said ‘no I came fourth’.

“Why are you all celebrating then,” he asked. “I don’t know,” I said.

Far from being satisfied, Murphy has spent around 250 days last year out of the country chasing better than London 2012 and since then has been to Rio seven times. She will travel back to the venue another three or four times before August. Learning the geography and climate system and tides has become a necessity. All the teams are over there cramming.

“There’s probably eight girls that could all easily win the gold medal in the Laser Radial Class. There’s maybe three or four that are likely to win the gold medal but eight of us definitely have the potential to win. I think on my good days I’m in that eight,” she says.

Complex places

Rio isn’t Weymouth. Everything is different to England’s south coast from its home feel to the fresh conditions that sailing in Dublin Bay has taught her to love.

The Rio waters have a split personality which command wariness and respect.

“Rio is one of the most complex places I’ve ever sailed,” she says. “Sailing is inside this huge bay but it has a very small entrance out into the Atlantic Ocean. The tidal flow is massive but there’s also a shipping lane. The shipping lane is very deep and then shallower on the sides. So tides coming in come in much faster in the shipping lane. Then there is a small island in the entrance of the bay and there is a tidal eddy behind. When the tide is coming in the water is flooding back and upwards.

“These complicated features you need time to understand. Every day is different. . . Sometimes the wind is coming from the left of the Sugarloaf mountain and sometimes it’s from the right. When the tide’s coming in the water is flat, when it’s going out there are waves. There’s the airport too, where the airplanes give wind gusts . . . there’s a lot, a lot of different variables.”

The wind will be between 8 and 13 knots. She’d prefer more but that won’t happen. The water is not clean but can be acceptable. She won’t let it be an issue, the floating furniture, animal carcasses or Zica virus. Any idea of a green Olympics is absurd. But for Murphy they are all problems that can heap up if you let them. She is looking for solutions.

“No the water isn’t clean,” she says wavering a little. “It depends on what the weather is like. If it’s sunny and nice the water is pretty good. If the tide is coming in and it’s sunny nice the water is very good.

“If the tide is going out not so good. If it’s been raining and the tide’s going out, it’s bad . . . But you get on with it. There’s no fear.”

The expectations are stacked high and she knows it. Those in the sailing world know that her strengths are more naturally aligned with Weymouth than Rio.

She also understands that she is not going into Rio with the same run of top finishes at regattas she had approaching London or more impressively after London. Following the Games, Murphy won two World Cup events and became the 2013 European Champion.

“Yeah 2013, it was like I’m going to take over the world,” she says. “Then I had a pretty average year in 2014. I never sailed that well and started doubting myself. A lot of it is a mental game.”

The next few months will more informative about Rio chances. The European Championships are in three weeks’ time in Grand Canaria followed by the World Cup in April and the Olympics in August.

They are worlds away from today in Dublin; a blue clear sky with ice winds cutting across the city. Days like this in the choppy waters of Dun Laoghaire she speaks about like a comforting but irritating old friend.

“Today it’s going to be so miserable,”she says with certainty. “You can get chilblains in your fingers when it is this cold. If you bash your fingers off the side of the boat they come back to life. You are okay for about an hour. Then you’re freezing. No amount of bashing will help.”

My dream

Her family are sailors. Her mother Cathy, who competed in the Seoul Olympics, and father Con held the Round Ireland Record until it was broken last year.

They did it with the adventurer Steve Fossett, who subsequently disappeared in a plane accident in another project. He wanted two Irish people on his boat Dakota. They stepped up and 44 hours 20 minutes later they held the record.

It was Cathy who told her “not to freak out in 2012. Putting the shinning new Laser Radial into the water at Weymouth it fell off the trailer and scored the bottom. . The panic was set aside and she went out to win the first four of 11 Olympic races.

“I’m very aware of people going ‘sure you’re guaranteed the gold now’,” says Murphy. “We’ll I’m probably not guaranteed the gold. It’s my dream to win the gold. Maybe galvanised by Weymouth,” she says. There’ just China, Holland, Belgium, Britain and the rest to beat.

“I’ve grown up sailing in windy conditions. . . That’s what you become good at,” she says. “I’m pretty tall so I can use leverage to flatten the boat. When you’re leaning out, the further you can get your shoulders and your head out the flatter the boat and if it’s flat it’s going to go faster. That’s the whole idea.

“When it’s light winds everything has to be perfect. Make one small mistake and you will be punished. Rio is light winds and that’s the challenge. It’s something I’ve been working on for three years,” she says.

Murphy hits the bike and cycles back towards a life often more grind than glamorous. Dublin traffic and Dun Laoghaire water in February, riding the wind.