Among those disadvantaged by the unexpected result of the Belmont Stakes was President Jimmy Carter. In racetrack parlance, Carter has been making every poll a losing one, and was in need of something prideful to brag about. Something piquant to take to the voting public, like: Only administration since Franklin Roosevelt to produce three Triple Crown winners.

Alas, Spectacular Bid failed him in the Belmont stretch, lacking the equine reach to follow in the hoof-prints of Seattle Slew and Affirmed. And Mr. Carter was deprived.

At 30 cents on the dollar, the Bid finished a faltering third, showing all of the classic signs of fatigue on the race track. In the last quarter, his rear end was slewing this way and that, as if unhitched from the magnificent animal that had conquered all others in the Derby and Preakness.

The instant conclusion was that the 1 1/2-mile distance was too long for Spectacular Bid. It is always fashionable to say this about Belmont Stakes losers. This time it was possible, too, to point a finger at his rookie rider, Ron Franklin, for his questionable race-riding tactics.

The next day would come the explanation of trainer Bud Delp that in a morning-of-the-race accident at the barn, Spectacular Bid was snakebit by a safety pin. The groom, while removing the leg bandages, had fumbled one of the pins and the always tempestuous colt had thrashed about until he embedded the loose pin in his left front foot an inch deep. It bled, it was found, it was removed, and the stable's temptation to scratch the colt was overcome.

"You can't win the Belmont by staying in the barn," said Delp.

The pin was one explanation. Earlier, there had been another, by Ron Franklin, who had said he heard his horse gargling and appearing to choke in the late running. But Franklin said yesterday, after the pin incident was revealed, that he had been a liar about that gargling and choking stuff. He also said Bid favored his injured foot during the race.

In addition to being a liar, Franklin may have been in an uncommon hurry to get to the front and stay out of trouble, far ahead of General Assembly and Angel Cordero Jr., who may not have been sincere in saying he and Franklin were friends again. Their staged handshake in the Belmont stewards' room could not quite obliterate memories of their earlier vows to get each other following brushes on horseback in two earlier races.

Franklin appeared to be overeager also to take out after the 85-to-1 shot, Gallant Best, who held the lead for three quarters, in contrast to the rider on Coastal, Ruben Hernandez, who was giving his colt a bit of a breather in fourth place.

But it was when the field turned for home that Franklin and his charcoal gray 3-to-10 favorite began to lose the Belmont Stakes to a horse of another color. The brightly hued chestnut, Coastal, was being heard from and when Franklin and the Bid swung a bit wide, he was inviting Coastal to go for the fast inside lane where speed horses had been winning all day at Belmont.

Coastal cut the corner exactly as he did two weeks before when he first gained attention by winning the Peter Pan by 13 lenths. Coastal got the lead, never gave it back, and Spectacular Bid also lost his try at keeping out of second place, to Golden Act, whom he had soundly beaten in the Derby and Preakness.

Bid's drift to the outside entering the homestretch was the typical behavior of a tiring horse. They drift out, rarely lug in, much in the pattern of tiring baseball pitchers whose offerings are always wild high, never wild low. But with his colt already disposed to drift, it was no help either when Franklin persisted in whipping from the left side.

It was crude of Cordero to exalt in the jockey's room at the defeat of Sepctacular Bid and Franklin by another horse not his own.

On General Assembly, going into the far turn. Cordero still was taking a shot at Bid, pushing Franklin to more speed. He spent his own mount, finishing next to last, but it was, in a manner, Cordero's Revenge that Spectacular Bid was not the same running colt with a big punch when needed. That he may have been ailing was evident when Golden Act also passed him in the stretch, gaining 3 1/2 lengths on the favorite in the last quarter-mile.

There will be no more attempts by trainer Delp and others to compare Spectacular Bid with Secretariat. Several other notions were put to an end with that stretch run at Belmont, including the belief that Bid was a $20 million property for syndication as a Triple Crown winner. The fortunate Meyerhoff family lost, it is estimated, $8 million off that figure when Coastal, not their colt, came flying home.

There was also the immediate loss of a $5.5 million match-race purse between Triple Crown winners Spectacular Bid and Affirmed. Emissaries from Caesars World in Las Vegas, the casino people who want to make a smash entry into Atlantic City's gambling society, were on hand to make that offer to owners of the two steeds. It would have been run at the Atlantic City track, and Caesars World would have reaped the publicity.