Every day Cambodian men in straw hats and dust-covered clothes pedal bicycles into this huge settlement of refugees.They lean the vehicles against trees and settle down to haggle with Thais who have come to sell bundles of sarongs, blue jeans, canned milk and cigarettes. Business concluded, they lash the goods onto their bikes' special cargo racks and set out for markets towns inside Cambodia.

Two miles away, other Cambodians camp out beneath oxcarts near the Thai village of Nong Chan. There, Red Cross officials issue free 44 pounds of rice to every person who shows up. But these are not refugees either. The rice collected, they harness the oxen and the carts disappear down dirt tracks leading toward Cambodia.

This flow of food and goods across the Thai border is an important factor in attempts to revive Cambodia's ravished agriculture and economy.

Rice in quantities to feed more than 300,000 people is passed out at Nong Chan. No one can put a precise figure on the commercial trade but it certainly involves millions of dollars and has set the economy of nearby Thai towns into high gear.

The bicycle merchants' effect is not entirely positive, however. The trade favors those who have money, not those most in need of food or other essentials. It is fast draining Cambodia of what little gold and silver was hidden during the Khmer Rouge years. Furthermore, through taxation and confiscation, right-wing Khmer Serei guerrillas and Vietnamese troops backing the Heng Samrin government keep themselves in food and money.

For the merchant himself, the work is dangerous but can make him fabulously wealthy -- by Cambodian standards at least. Thus his wares reach all over the country. The costs are enormous but in just about every town, people find ways to buy food or clothing, or some small luxury -- scented soap, for instance -- that they could only dream about during the Khmer Rouge rule.

Cambodia now has no currency of its own. People use Thai baht in the west, Vietnamese dong in the east and rice and gold all over the country. Rice appears to be the most common medium. In recent months, however, it has become an inflated currency -- people find that their rice buys less and less.

This is, in fact, a good sign. It is evidence that Cambodians have more rice in their homes. The "money supply" has been augmented by a small harvest around New Year's and by the international relief effort -- thus prices, when expressed in rice have gone up, too.

Mr. Hot, a fit 27-year-old man from Kompong Cham Province in eastern Cambodia, was among the bicycle merchants shopping at Camp 204 last week. Controlled by Khmer Serei guerrillas, the camp has a large civilian population and is one of the border's largest black markets.

Hot said he planned to buy a general mix of consumer goods. "But I especially want bicycle tires," he explained. "In Cambodia there are hardly any at all."

At 204, tires sell for about $17, he said. In Kompong Cham, they currently fetch about 110 pounds of rice, or enough to feed one person for more than three months. Last fall, he said, when rice stocks were at their lowest, people would pay only 22 pounds.

Hot travels in a caravan of more than 100 bicycles -- this was his third trip to the border. Leaving 204, the first 30 miles is jungle trails. Then they reach good roads, and it is smooth riding down Highway 6 to Kompong Cham, about 200 miles to the southeast. The trip takes 5 days each way if nothing goes wrong.

There is always the danger of thieves. Another risk comes at the numerous checkpoints manned by Vietnamese soldiers. Sometimes they let the bikes through untouched, sometimes they take everything, sometimes only half, Hot said. Occasionally, the traders are arrested.

Still, enough people get through with enough goods to keep the bicycles "a common sight on the roads. Analysts see it as evidence that the Vietnamese are willing to tolerate the trade, provided that they get some of the merchandise. "They especially like cigarettes," Hot said.

He normally does not carry rice to Kompong Cham, as the market has ample supplies already. If he cannot sell everything there, he will take it on to the Vietnamese border. Either way, he hopes to take in 1,200 pounds of rice or its equivalent in gold and bank notes -- enough to feed him, his wife and child for almost a year. Hot will be a rich man and his neighbors will eat less but enjoy sarongs, rubber sandals and whatever else he packs aboard his bicycle.

While provinces close to Phnom Penh appear to have rice, serious shortages persist in the country's populous western provinces.

At Nong Chan village, civilians report from all over western Cambodia in oxcarts, on bicycles and on foot to collect a 44-pound ration, food for one person for six weeks. Rations for 200,000 people are going into Cambodia through Nong Chan.

U.S. officials see the feeding operation as a means of supplementing inadequate rations in the villages without permanently drawing people away to live in the border settlements. In the past 10 days, people have shown up in Nong Chan in rapidly increasing numbers leading relief officials to speculate that rice stocks are getting dangerously low again.

A mr. Chom brought an oxcart from a village north of Battambang with his wife and three children. It was his second trip -- on the first Vietnamese soldiers confiscated everything he was carrying. "They told us, there's no need to come here. We'll send rice to your village," Chom said as he sat under a primitive sunshade, waiting for rice to be issued.

Some observers have estimated that up to 70 percent of the rice ends up in Vietnamese hands. "It's a quartermaster operation for the Vietnamese border force, with Cambodian labor underpaid," said one American who follows refugee affairs closely.

Refugees say the Vietnamese eat some of the rice themselves, and sell some to Cambodians for cigarettes and other items in short supply. But as with the bicycle merchants, the soldiers' purpose seems to be to tax the trade heavily but not to wipe it out.

Many villagers feel it is worth the risk. Chom said that in his village, Heng Samrin officials were providing only three to four milk cans full of rice per month for each person -- about two pounds, enough for two days' eating.

Chom said he hoped to plant a full crop of rice when the rains come in early summer. Heng Samrin officials have promised seed, but so far none has appeared, he said. Foreign aid agencies are currently pumping in seed and other planting supplies through Phnom Penh and Konpong Som, but given Battambang's great distance and poor roads, they will be slow in reaching it.

If official channels fail, it is safe to predict that Cambodian farmers will turn to the private ones. Cambodia's economy so far has obeyed textbook rules on supply and demand unfailingly. If enough people want rice seed, the traveling salesmen with their bicycles will find a way to get it to them.