A Lafayette man has come up with a way to tether a dog to a bike safely. It's called the Bikerdog, and it hits store shelves around Boulder and Denver starting today.

"It's a neat little system," said Mark Scarafoni, manager of Cutting Edge Sports in Lafayette, where Bikerdog sells for $70.

Scarafoni said he decided to carry the device after trying it with his dog. He says it's safe and allows a dog to travel more places with its owner than just to the off-leash dog park.

Bikerdog consists of a dog harness, a 10-inch leash, a 10-inch flexible hard plastic post, and a patented "biker bone," which attaches the post to the bike frame at the rear wheel.

By fastening to the lowest fixed point on the bicycle, dogs are not able to pull riders off balance. The relatively short lead also keeps dogs from running into the spokes. And the leash and plastic post detach from the bike to serve as a short lead.

A test run over the sunny Easter weekend found two dogs that took immediately to the device. The only minor drawback was that the post, which sticks out to one side of the bike, has a tendency to bump the heel of riders with large feet.

Also, it's important to remember that bikes are capable of outrunning dogs. So try to keep your speed at a dog's jogging pace.

Bikerdog began nearly six years ago, when inventor Dean Keyek-Franssen bought a chocolate Labrador puppy and immediately realized he had a problem. He didn't have any way to go for a bike ride with his dog, his wife, their infant and their 3-year-old child.

His wife could ride her own bike. And the kids had a great time being towed by the couple's Burley child carrier. But there was nowhere to hook the dog.

The family searched all over for a device and found one, called a Springer, now available at www.springerusa.com. That $45 device is similar to the Bikerdog and incorporates a large spring that is supposed to absorb the jolts of an errant puppy.

"We got that, and it broke," Keyek-Franssen said. "So we invented the better mouse trap."

The family moved to Lafayette four years ago. In the meantime, Keyek-Franssen, 37, secured a patent and a trademark. After selling hundreds of Bikerdogs over the past nine months from his Web site, www.bikerdog.com, he has convinced REI, McGuckin Hardware, Cutting Edge Sports and Bark Avenue in Lafayette to stock his product.

While strapping a dog to a bicycle doesn't seem like a safe idea at first, Keyek-Franssen says he has received only positive feedback about Bikerdog.

"We know it's going to take off," he said.