The onus should be on motorists involved in accidents with cyclists or pedestrians to prove they were not at fault, an inquiry into the ACT's most vulnerable road users has been told.

Lobby Group Pedal Power has also called for slower speed limits to be imposed on major roads when it is raining heavily or there is traffic congestion.

And the group says cyclists to be permitted to ride across pedestrian crossings instead of dismounting and walking their bikes across the road.

In submissions to an ACT Assembly inquiry into vulnerable road users, law firm Maurice Blackburn and the Motorcycle Riders Association of the ACT have both called for a feasibility study on the impact of introducing "strict liability''.

Under strict liability, the onus would be on the more powerful road user to prove that they were not on fault in an accident.

Pedal Power went a step further, calling for the rule to be imposed for accidents involving cars and bicycles.

"Drivers who kill or injure people riding bicycles rarely receive significant penalties from the criminal justice system,'' the Pedal Power submission said.

"Unlike offences related to speeding which attract strict liability, serious offences related to the killing or injuring of road users require the prosecution to prove intent.

"Defences such as 'the sun blinded me so I didn't see him' lead to the dismissal of charges.''

The group also wanted "tiered penalties'' for offences related to vehicle crashes so that more serious breaches attracted higher penalties.

But Pedal Power believed that the requirement for cyclists to walk across pedestrian crossing to be scrapped.

"This is anomalous in a jurisdiction where bicycles are allowed on all footpaths. The law is neither observed nor enforced,' it said.

Pedal Power said the speed limit on more ACT roads should be lowered to 50km/h to improve safety for cyclists and pedestrians and traffic-calming measures should be installed in 40km/h zones.

The Motorcycle Riders Association joined Pedal Power in calling for improvements to road infrastructure to improve safety but warned that on-road cycle lanes could be dangerous.

"While the MRA ACT encourages the use of bicycles on the ACT roads and footpaths, on-road cycle lanes should not be a norm at the expense of crash avoidance space for other road users'' the group said in its submission.

"For example, the narrowing the lanes on Northbourne Avenue adversely impacts on crash avoidance space.''

The motor cyclists' group wanted wire rope safety barriers installed next to roads in line with best practice and warned against a proliferation of road-side traffic signs which could be a collision hazard.

Thousands of Canberrans are expected to cycle to work on Wednesday as part of the annual Ride to Work Day.