LEIGH SALES, PRESENTER: The death of a cyclist knocked under a truck by a motorist opening a car door has reignited the debate about how we share the nation's roads.

Cycling's on the rise around the country as people take it up for health, environmental and financial reasons.

While the road toll overall is decreasing, the number of cyclists dying each year is rising and cycling groups say not enough is being done to protect them.

Karen Percy reports, and a warning: you may find some images in this story disturbing.

KAREN PERCY, REPORTER: Alberto Paulon was proud of his new bike. It was his favourite colour, and despite mocking from his friends, the 25-year-old Italian chef loved it.

CRISTINA CANNEDA, ALBERTO'S FIANCEE: Albi was (laughs) such a good person. He was just the funniest man I ever met. He always make me laugh and he always find the good things in everything.

KAREN PERCY: On Friday, February 27th at about 4 pm, Alberto set off for work riding with his fianc Christina Canneda along Sydney Road in the inner-city Melbourne suburb of Brunswick.

CRISTINA CANNEDA: And then we just start to ride. Albi told me, "Watch out, the truck." And then I heard a terrible noise. That's all.

KAREN PERCY: A car driver had opened her door into Alberto's path. He was knocked under a truck.

CRISTINA CANNEDA: So I saw him. He was laying on the street in the middle of the street and he was just laying there like he was unconscious. ... And he was looking at me and I was just screaming, "Albi, no! Please, no!" And then ... (becoming emotional) ... everyone came, help us.

DEAN MCGOWEN, VIC POLICE: Albi stood no chance in the accident. He had no time to react. Only two cars behind the truck that was unfortunate enough to strike Albi was a police car. The Brunswick divisional van, they were pretty much on the scene within about 10 seconds and commenced CPR.

KAREN PERCY: He died at the scene

In densely-populated Brunswick, one in 10 residents rides every day.

RYAN BILZSTA, SAMSON CYCLES: In the last five to 10 years there's been a pretty big increase in your recreational cyclists, your commuting cyclists. Because we're not far from the city, in the inner-north, close to universities, schools, all that sort of thing, a lot of people are looking at bikes as an inexpensive and easy way to get around.

KAREN PERCY: Ryan Bilzsta sold Alberto Paulon his bike just two weeks ago.

RYAN BILZSTA: He came in with his girlfriend. It was a very quick sale, not a lot of questions. Nice guy.

KAREN PERCY: Across the country, cyclist numbers are growing and so are the risks.

TRACEY GAUDRY, CEO, AMY GILLETT FOUNDATION: The road toll is decreasing across the country on the whole except for bicycle riders. So what is happening is that the work that is being done to protect occupants of motor vehicles, not enough is being done to protect vulnerable road users, including bike riders.

KAREN PERCY: Last Friday during peak hour, Sydney Road, a major route out of Melbourne, was shut down in order to honour Alberto Paulon. His Italian family has come to take him home.

They joined the thousands of bike riders and local residents who want other road users to be more aware of the dangers on increasingly congested roads.

CRISTINA CANNEDA: Remember what we are here for. Remember riders we have lost to car dooring. I want to make sure that something's going to change. I cannot think that this can happen again.

KAREN PERCY: Alberto Paulon's boss of two and a half years, Melbourne restaurateur Marco Donnini, has been supporting his family during their difficult time in Australia.

MARCO DONNINI, ALBERTO'S EMPLOYER: You're sending off your children to - around the world to be able to go and live a better life and then something like this happens and you feel so disassociated with the whole scenario. So I found it to be our responsibility to be able to just make them aware that he was at his happiest here and that there we lots of people that loved him.

KAREN PERCY: Alberto Paulon was one of about 10,000 cylclists who commute around Melbourne's inner-city each day.

An increase in the number of bike lanes and higher fines hasn't stopped dooring accidents.

CINDY CALDEIRA, CYCLIST: My mum was involved in a dooring accident in '89.

KAREN PERCY: Cindy Caldeira was 16 when her mother had a bike accident in a quiet Port Melbourne street.

CINDY CALDEIRA: She basically catapulted over the door. She went into a coma on impact and didn't come out of it and basically died of brain injury.

KAREN PERCY: In the past five years, Cindy Caldeira has had two run-ins with cars and was herself doored in the inner-city.

CINDY CALDEIRA: It just happens very fast and I think the automatic reaction is just to go into shock.

KAREN PERCY: On Friday, Ms Caldeira and many others paid tribute to a stranger. 25 years after losing her mother, she knows all too well that cyclists still face the same dangers.

CINDY CALDEIRA: It's still a issue that needs to be addressed. You can have as much infrastructure in place, but I think it comes down to every single person's awareness about bicycles and especially when you're in a motor vehicle.

TRACEY GAUDRY: Car drivers and passengers need to recognise that the car door is potentially a deadly weapon and was in this situation and it's responsible behaviour when getting in and out of the car.

LEIGH SALES: Karen Percy reporting.