Rhys Wilkins was sentenced to 12 months in August, with a non-parole period of nine months, for the January 2010 crash which claimed the life of James Keenan and for other unrelated driving offences.

The 61-year-old Mr Keenan spent a fortnight in intensive care with head trauma before succumbing to his injuries.

Now-Chief Magistrate Lorraine Walker found Wilkins guilty of negligent driving occasioning death in the ACT Magistrates Court earlier this year after finding Wilkins had an obligation to avoid the killer crash.

But his lawyer has told the ACT Supreme Court Wilkins had a duty to concentrate on the road ahead rather than look back at the cyclist.

The 36-year-old driver, heading to the shops in his Mitsubishi Evolution, saw Mr Keenan riding along Sternberg Crescent in Wanniassa on the fateful morning. The Fadden man overtook the cyclist, indicated to turn left on to Ashley Drive and began negotiating the corner before the bike struck the rear of the car, sending Mr Keenan tumbling across the road.

There were no allegations Wilkins was speeding or under the influence of substances at the time of the crash, although his licence was suspended at the time.

Ms Walker concluded Wilkins had seen the cyclist as he overtook and, as a result, had a duty of care to keep a watchful eye out for the vulnerable road user before taking the turn.

But at yesterday's appeal hearing, the man's lawyer Richard Davies, submitted Wilkins' duty was to execute a safe turn and not brake suddenly.

Mr Davies said the magistrate suggested there might have been some negligence on the part of the cyclist at the time of the crash.

Justice Richard Refshauge yesterday said the conviction appeal hinged upon whether the motorist had a duty to establish where Mr Keenan was in relation to the car.

The defence has also appealed against Ms Walker's sentence, arguing the 12-month sentence was manifestly excessive.

Wilkins' was at the same time sentenced for getting back behind the wheel just 10 days after the crash, despite being disqualified from driving and for another disqualified driving offence occurring a mere months later.

Ms Walker, in sentencing, described the man as a ''contumacious'' driving offender.

The magistrate, as part of the broader sentence, extended an earlier suspended sentence by three months and ordered it to be served in full-time custody. The territory is one of few jurisdictions which allows a judicial officer to extend a suspended sentence after a breach, a rarely-used sentencing option.

But prosecutor James Lawton said Wilkins' case was serious enough to warrant the tougher penalty.

Justice Refshauge said he was worried about opening the floodgates for extending suspended sentences following breaches.

The judge reserved his decision in relation to the appeals against both the conviction and sentence.