The family of a star WA triathlete killed in an alleged hit-and-run in Welshpool on Saturday morning have called for the carnage on road cyclists to stop.

Brynt McSwain, a three-time Australian representative, was knocked off his bicycle when a white utility allegedly struck him as he rode along Kewdale Road about 7.40am.

Major crash investigators have charged a 38-year-old Leda man over Mr McSwain's death, claiming the driver of the vehicle did not stop to help the stricken cyclist.

Several motorists rushed to help the 31-year-old but he died at the scene.

Police allege that about five minutes later the same white utility smashed into a light pole on Nicholson Road in Thornlie before coming to a stop on a grass embankment at the southbound entry to Roe Highway.

The driver was charged with dangerous driving occasioning death, refusing a breath test, failure to stop and render assistance and failure to report a crash.

Police figures show six cyclists were killed on WA roads last year and in a brave front yesterday girlfriend Katey Gibb and Mr McSwain's mother Snow pleaded with drivers to take more care in sharing the road with cyclists.

"Over time it's got worse," Ms Gibb, also a champion triathlete, said. "There is very much a cyclist-driver mentality out there. People just need to care more for each other and it needs to stop. It's as simple as that."