When Peachtree Road Race runners receive their numbers this month, they'll notice something new attached: a colorful strip with a silicon chip inside, their key to timing the run.

For the first time, all 55,000 runners will be timed during the annual July 4th race. Until this year, only seeded runners and those in "Time Group One" received electronic timing devices for the 10K. The new time tracking tags are disposable, which eased officials' fears of a tag-return bottleneck after the race.

"We really wanted to make sure that everything would work out, given the volume," said Tracy Lott, the Atlanta Track Club's director of marketing and communications. "It would be too difficult to retrieve all the chips from 55,000 runners."

Participants should receive a ChronoTrack D-Tag with their race number in mid-June. On race day, they can peel off adhesive on the weather-proof tag and loop it around their shoe laces. Runners aren't required to wear the timing tags but Bob Finnegan, ChronoTrack's business development director, expects that most will.

"People like to know," he said. "It is a race."

The tags have recorded times for more than 2 million runners since just last year, including participants in the Atlanta's Finest 5K, Atlanta Women's 5K and 2008's Weather Channel Atlanta Marathon and Half Marathon.

How does it work?

The system uses UHF technology to send and receive signals that track when runners start and finish the race. For best results, runners should wear tags on their shoes and be certain to cross the start and finish lines.

How do I attach it?

On race day, remove the instructions, peel away the adhesive and attach the tag to shoe laces by looping it around and sticking it together to make a "D" shape. Runners without laces should fold it into the "D" shape and wear it on a Velcro loop around an ankle. ChronoTrack says runners shouldn't tie, puncture or cut tags, flatten them under laces or leave them on their bibs. Volunteers will be available on race day to help runners attach them.

When will I receive it?

Timing tags will be attached to race numbers, which will be sent to runners in mid-June. Runners who haven't received packets by June 22 can contact the club at racenumber@atlantatrackclub.org.

Will tags get in the way?

ChronoTrack's Finnegan says no: "They weigh almost nothing. It makes a circle around the shoe laces. People don't look straight down at their feet when they run. Ninety-nine percent of the feedback is that they like them better than the old timers."

Where can I learn more?

The Atlanta Track Club Web site has information about the Peachtree Road Race and timing tags: www.atlantatrackclub.org.

ChronoTrack, maker of the timing tags, offers FAQs and demonstrations on its "For Athletes" Web site: www.chronotrack.com/for-athletes.