Two veteran endurance bicycle riders, who plan to ride across the 1,938-mile Pony Express Trail in June, will spend nearly 24 hours in their cycle saddles Friday and Saturday during a practice run at the Salt Lake International Center.

Jay Aldous, Salt Lake City, and Matt DeWaal, Bountiful, started out at 5:30 a.m. Friday and expect to complete 400 miles by the time they finish their ride at 5:30 a.m. Saturday.The two will wear heart monitors and eat a special diet composed of a liquid carbohydrate and super-rich candy bars.

"We will both probably expend about 12,000 calories during the 24 hours," Aldous said. "We won't eat that much food, so we'll probably lose a few pounds."

The two will ride around three different loops at the center west of Salt Lake International Airport. One is 1.6 miles long, another is 2.4 and a third is 1.2 miles.

"We'll take a five-minute break every two hours, eat on our bikes, and we'll have friends on and off through the day to help us." Aldous said information from their heart monitors will be entered into a computer every four hours.

They will ride four different kinds of bikes: a mountain bike, a road bike and two tandem bikes, or bicycles built for two - one built for dirt and one for pavement.

When riding the tandem bikes, they will trade riding in front and back and will have to stop long enough to change their seats and adjust them.

"We will travel about 18-19 mph during the first 18 hours and then settle down to about 13 or 14 mph the last six hours."

Aldous said he has seen horse and people relay races that covered 100 miles. "Horses took all day. Runners did it in 12-13 hours. I expect horses during the days of the Pony Express, from April 1860 to October 1861, averaged about 10 mph for a 10- to 15-mile leg. Mail sent by Pony Express took 10 days to be delivered.

"We expect to leave Sacramento, Calif., the western terminus of the Pony Express, June 6 and ride east to St. Joseph, Mo., in 10 days, arriving June 16. We'll probably sleep about six hours a day over the 10 days."

Aldous said he and DeWaal have covered the entire 1,938-mile course by vehicle. "Nevada has some of the toughest areas. A week ago, we drove over one stretch of the Pony Express in Nevada and spent hours digging a four-wheel-drive vehicle out of the mud."

The two cyclists will make two more practice rides before June 6. Next weekend, they will ride over the Pony Express Trail in Wyoming and the following weekend they will ride someplace in Utah close to Salt Lake City.

While few bicycles are made in the United States and most modern bicycles are now made overseas and imported into America, Aldous said, the two cyclists will be riding one bicycle made in Salt Lake City.

Aldous said his mountain bike is made by Reflex Co., a subsidiary of Easton Inc., which makes archery equipment.