LIBERTY, Mo. -- A 45-year-old woman has died following a bicycle accident Wednesday morning in Liberty, officials said.

Police said Susan Brewer was riding her bicycle south on Highway 291 when a pickup truck hit her from behind. Brewer died Thursday at a local hospital.

Bicyclist advocates said they want both bikers and drivers to be more careful on the road.

"Always be looking over your shoulder, looking in front of you. Assume people can't see you," cyclist James Joerke told KMBC's Bev Chapman.

Joerke has been biking to work for two years.

"I've ridden my bike 100 times. My total mileage is about 1,200 miles," he said.

Joerke said most drivers he meets on the road are courteous and careful, but he is aware of the danger on Kansas City streets this summer.

He said Friday morning a driver passed him, then put on the brakes and turned right in front of him.

"So then I had to quickly break to avoid hitting the car," Joerke said.

According to the Missouri Bicycle Federation, one of the most common car-bike collisions is when a driver turns right in front of a bicyclist, because many drivers can't estimate a cyclist's speed.

"A bicycle in city traffic is going as fast as motorists, especially if they're slowing down to make a turn. Now the bike is going faster than the motorist," said Brent Hugh with Missouri Bicycle Federation.

Hugh said another danger for bicyclists are big rigs that swerve in order to turn. Bikers who end up in the truck's blind spot can be killed.

Twice this summer, two bicyclists in the metro area have died in crashes with big trucks, Chapman reported.

"This is really a very easily preventable accident. You just don't go up alongside trucks," Hugh said.

Joerke said he's seeing more bicyclists on the road, probably as a result of high gas prices. He said some of the cyclists aren't used to riding in traffic, which can be dangerous.

Joerke, who is the air quality program manager for the Mid-America Regional Council, said he rides to work to stay in shape and to make a difference.

Chapman reported that more bicyclists are expected to be on the road this weekend training for the MS 150 Bike Tour.