The cyclist isn't a member of the group Cyclists Action Movement West, or CAMWest whose secretary, Rob Kemp, of Rooty Hill, said there was no excuse for breaking the law.

The bus had overtaken the bike, allegedly too closely.

Mr Kemp said the cyclist should have noted the number of the bus or taken a photo of it and reported the incident to the police.

He said CAMWest members were not encouraged to ride along the bus-exclusive transitway.

``I know some individuals and cyclists from other groups use the bus transitway to avoid having to stop at traffic lights and intersections for other vehicles,'' he said. ``This is despite an excellent cycleway all the way from Westmead to Rouse Hill and Seven Hills.''

Mr Kemp said this after announcing that CAMWest would hold its first public 20-kilometre Night Ride for cyclists from Rooty Hill station to Quakers Hill for this year this Friday, November6.

``We'll be using only the cycleway and all cyclists must comply with this rule for safety reasons,'' he said.

``Those aged16 and older are welcome to join us.''

All riders must wear cycling gear and their bikes must have lights.

Those keen to join can meet Mr Kemp at Rooty Hill station at 6.30pm or call him, 98648797.

Commenting on the assault, Transport Minister David Campbell said the cyclist had no right to be riding in the T-way and that it was also offensive and unacceptable to exercise physical violence in any circumstances.

Police have video footage of the incident and have appealed to the cyclist to identify himself.

A spokesman said the cyclist was wearing a long-sleeved, skin-tight top, a light-blue bike shirt and dark knee-length pants. He wore fingerless gloves and a black-and-white helmet and is described as being of white/European appearance, aged in his 30s and about 178cm tall.

Any information to Crime Stoppers, 1800333000 (all information treated as confidential).