The number of cyclists treated at Perth's major trauma unit has risen 45 per cent in 12 months.

And doctors say the severity of injuries is worsening, particularly spinal injuries.

"The worst injuries we've had are people getting run over by trucks, dragged under them … some are losing limbs, having muscles ripped off bones … awful injuries," State Major Trauma Unit director Sudhakar Rao said.

Last year, 120 cyclists were treated at the unit, up from 83 in 2012 and 77 in 2011.

Up until the end of May this year, 66 cyclists were treated, 14 of whom were not wearing a helmet.

One-fifth of cyclists who have been treated over the past four years were not wearing a helmet. Most victims were men aged between 35 and 45.

GRIEVING DAD HORRIFIED BY ROAD BEHAVIOUR

Dr Rao said most cycling injuries involved collisions with cars.

"We are seeing very high-risk, serious injuries … spine and head injuries, leg injuries, rib fractures and punctured lungs," Dr Rao said. "The degree of severity has started to trend upwards, and we're seeing an increased number of spinal injuries."

Bicycling WA chief executive Jeremey Murray said the figures were concerning.

"There is often a misconception in terms of riders' rights," he said. "They are legally allowed to ride two abreast, they are allowed to be on the road.

"But there are also behaviours that cyclists are involved in … you get them doing stupid things on the roads, not indicating, riding without helmets."

The group also wants speed limits on suburban roads reduced as part of its strategy to double cycling participation rates by 2020.

Mr Murray said with more people riding, new infrastructure such as bike paths was essential.

Police Minister Liza Harvey said the Government was working on a "share the road" campaign to remind all road users to be wary of others.

Grieving father Ian Anderson has lobbied to improve cyclist safety since Ross Thomas Murray struck Tim, 26, as he rode along Curtin Avenue in Mosman Park. Tim was wearing high-visibility clothing, a helmet and had lights on his bike when he was hit.