Why don't cyclists always keep left?

It's a contention often expressed on talkback radio and social media – especially when people are analysing yet another viral video of a collision between a bicycle and a motor vehicle.

"I thought the law said bicycles had to keep left! Sure, the driver shouldn't have hit him, but if he'd been further over to the side …"

It may surprise some to learn that "keep left" is not a law aimed specifically at bicycles. It is a general road rule.

Road rule 129 is applicable Australia-wide, and states that both drivers and cyclists "on a road (except a multi-lane road) must drive as near as practicable to the far left side of the road".

But what does "practicable" mean? Rob Berry, general manager of cycle training company BikeWise, says his organisation teaches riders that "it's as far left as is safe and effective and reasonable for you to be".

Meanwhile, Garry Brennan of Bicycle Network says having to keep to the extreme left would be an "unreasonable requirement"  because of the many hazards a rider can face on the edge of the road. 

As a VicRoads spokeswoman told me: "Reasons why a bicycle or driver may not be able to stay to the left within the lane would have to be judged according to the circumstances they find themselves in."

And quite often, a rider's reasons for moving further to the right might not always be obvious for a non-cyclist. Here are a few scenarios.

Avoiding the door zone

I've written about this several times before, but it deserves regular repeating – riding close to a line of cars can be a risky prospect, even if there is a bike lane in the "door zone of death".


For a driver, it can look like churlish behaviour: "Why don't they keep left, so I can get past?" But if a door is flung open, and knocks the rider into the path of a vehicle, the outcome can be catastrophic. 

Narrow roads and lanes

Riding on the extreme edge of a narrow road or lane can put a rider in conflict with a motorist who thinks there is sufficient space to pass in the lane, when there isn't. 

Garry Brennan of Bicycle Network says that when riding in the traffic lane, "an old rule of thumb is to ride in the left tyre track of the motor vehicles. Then drivers who want to pass you are subject to the passing rules - they can pass you by indicating, crossing the centre line, and passing only when they have a clear view of oncoming traffic and it is safe to do so."

Dodgy surfaces

A bicycle is a thin-wheeled vehicle that relies upon balance to stay upright. As such, it is vulnerable to uneven surfaces.

Riders are adept at scouring the way ahead for hazards that mean little or nothing to other road users, such as potholes, tram tracks, inspection covers and cement seams running in the direction of travel. Not to forget painted surfaces that can turn slippery in the rain.

Pinch points

Roundabouts and traffic calming devices, such as narrowed roadways between islands, can help to moderate vehicle speed while providing better opportunities for pedestrians to cross the road.

But on a bike, they can be a challenge – you don't want to be squeezing through small spaces alongside a car. After signalling and making sure the way is clear, I find it's best to move towards the centre of the lane to get through safely. And don't wait until the last second to do so. 

Shonky shoulders

The edge of a road can be a repository for all manner of hazards, such as gravel, branches, roadkill and smashed glass, which can keep you well clear of the gutter. 

Cyclists are also permitted - but not obliged - to ride to the left of the line marking the edge of the road. While this is usually a boon to all road users, some road shoulders can also have inferior surfaces. If a bike rider is staying off the shoulder, it's probably a shocker.

The ultimate responsibility

Of course, what's safe on a particular day might not be practicable the next - and part of the challenge is to signal your intentions clearly as road conditions change. 

"The principle is to be predictable and communicate with people," says Berry. "I'll look back at people and let them know that I know they're there, but as soon as I've gone through the section I move and let them pass. People drive past me and give me a smile and a wave - they understand that I needed that space."

Of course, there may be occasions when a rider is being unthinking, or even downright unhelpful, in the way they occupy the road. 

But the ultimate responsibility of the person in the overtaking vehicle is to pass safely. In other words, when it's practicable.

Fairfax journalist Michael O'Reilly has written the On Your Bike blog since 2011. He has won a Cycling Promotion Fund media award and is a regular voice for cycling on radio and television.

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