How could you miss seeing a 60 lb. rock in the way?

Bicyclist grateful for his helmet

'LITTLETON – Several teens face charges after police say they placed a 60 pound rock on a bike trail leaving a cyclist injured.

Police arrested the teens shortly after the incident Monday afternoon, and they have since been released into the custody of their parents.

Littleton Police say the accident happened on the Mary Carter Greenway/South Platte River Trail at West Belleview Avenue.

Denver resident John Cannon, 48, told police he was heading south on the concrete bike path when he collided with a large rock that had appeared to have been deliberately placed in the middle of the path.

"At the very last instant, I think I saw it when I heard the wheel hit it or the frame start to break, next thing I know I was upside down and on my head," said Cannon.

Cannon suffered a broken collar bone and bruised shoulder. He was transported to Swedish Medical Center Monday where he was treated and released. However, Cannon could be having surgery soon.

Littleton Police say the trail dips down before the Belleview bridge to the point where a rider's vision is cut off from a late afternoon shadow, and with sunglasses it can be especially difficult to see dark objects on the path.

"It's perfectly reasonable to assume with all those conditions, that the rock sort of blended in and he just was not able to see it," said Sgt. Trent Cooper with Littleton Police.

Police arrested three juveniles, two of whom are 13 years old and one who is 15 years old. Two of them were cited with misdemeanor assault and criminal mischief charges. One juvenile was not charged.

Police say the two could face a fine of up to $1,000 for each charge.

Cannon's helmet shows a few scuffs on its shell and a number of cracks on the inside liner showing where his forehead pressed hard upon impact on the ground.

"That helmet probably saved my life or at least saved me from being a cripple," said Cannon.

Cannon is a veteran bicyclist and counts up "tens of thousands of miles from all over the world."

From Alaska, New Zealand, and Italy, but a quiet afternoon ride in Colorado turned out to be the one that will keep him off a bike for at least two months.

"I've ridden on all kinds of roads, steep up, steep down, under bridges, in the dark, but I've never seen anything like this before," said Cannon.'