ACT Policing said the 49-year-old rider from NSW was travelling along Kingsford Smith Drive when he came off his Australia Post bike around 1.15pm.

Sergeant Rod Anderson said no other cars or objects were involved in the crash.

"He hasn't collided with anything, on or off the road, and no other vehicle was involved," Sergeant Anderson said.

Kingsford Smith Dr was blocked off at the site of the crash for several hours and traffic was diverted.

She said the road was not expected to be reopened for several hours.

It is the seventh fatality on ACT roads this year and the third involving a motorcyclist.

No further details could be released about the rider as police are yet to contact next of kin.

The area is signposted as an accident zone, the latest death bringing the total number of fatalities in the area since the late 1970s to 11.

Sergeant Anderson the incident was still under investigation, though speed was not suspected as a factor, and a report would be prepared for the coroner.

"We will look into all those circumstances - the road conditions, the weather conditions, the condition of the bike and the condition of the rider." he said.

"If there's anything in that, such as road design, and we do have someone here from Roads ACT to look at that, we'll certainly take that into account."

The road has now reopened.