Carl Smith's bike snapped in half after a collision with sheep on a Canterbury road.

Carl Smith says he is lucky to be alive after hitting a sheep at high speed while riding down a steep Canterbury road, causing the bike to snap in half.

The accident comes weeks after the NZ Transport Agency (NZTA) urged Banks Peninsula farmers to check fences to stop stock from wandering and keep road users safe.

About 5pm Tuesday, Smith was riding his usual hour-long route home from work up Dyers Pass Rd, along the top of Summit Rd and down a route known as The Bastard, towards Gebbies Pass Rd.

"I was coming down the hill going really fast, because it's a 12 per cent grade, and doing about 50 or 60 [kmh] winding around the corners.

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"I come around the corner and there's a sheep there.

John Kirk-Anderson/Fairfax NZ Smiths shows off his bumps and bruises.

"I tried to go around him and he just went forward, like lunged forward right at the last minute and smack, straight into him."

Smith said he heard a "bang" and then started flying off the saddle of his six-week-old bike.

"I was straight on the road. I think I rolled over once and just slid and I was on my side for about 10 minutes.

SUPPLIED A close up of the break in Carl Smith's bike frame.

"My bike was on the other side of the road, on the cliff side just destroyed, and the sheep just wandered off."

He ended up being flung about eight metres and believed his injuries could have been far worse than the scrapes to his arms and legs and bruising to his ribs and pelvis.

"I could've quite easily died.

"My helmet's got a big scuff on it so obviously that did something to save me, or a back injury or something like that, or just gone off the cliff. It's pretty scary.

At first, Smith thought he had broken his hip. He was unable to move because of the pain.

A passerby from Auckland tried to call an ambulance and waited for Smith's wife to arrive.

Having stock out on the road was "extremely dangerous", Smith said. He planned to notify police.

In mid-December, the NZTA said it had received multiple reports from police of stock wandering State Highway 75.

NZTA journey manager Lee Wright said this posed a serious safety risk on highways and local roads.

"The Transport Agency is reminding rural property owners that they are liable for any damage caused by their animals and if they cause a crash and negligence is proven, the livestock owner may be prosecuted," she said.