Before the Kentucky Derby, trainer Bud Delp said he could conceive of only one way that Spectacular Bid might be beaten: if another Secretariat were in the field.

Delp proved to be as astute a handicapper as he is a conditioner. Secretariat was probably the only Derby winner of the decade who could have defeated Spectacular Bid on Saturday.

To many of the people who watched him at Churchill Downs, the gray colt's perfomance might not have seemed so brilliant. His margin of victory, 2 3/4 lengths, was not awesome. His time, 2:02 2/5 for a mile and one-quarter, looked rather unimpressive. It was the slowest Derby since 1974.

But Spectacular Bid's time was slow only because the racing strip was slow. Although officially labeled "fast," it had been inundated by two days of heavy rain before the Derby and never dried out.

It is possible to measure the condition of a racing strip with some precision and as a fanatical speed handicapper, I like to perform this intellectual exercise to put the performances of big-name horses into historical perspective.

Churchill Downs runs certain types of races on every Derby day that form the basis for comparing track conditions in different years.

The Debutante Stakes for 2-year-old fillies, the Twin Spires Purse for 3-year-old colts and certain other events are contested before every Derby. By calculating the average time for these races, and then comparing this year's times with the average, ii is possible to judge the inherent speed of the track with accuracy.

For example, the average winning time for the five-furlong Debutante is 58 2/5 seconds; on Saturday it was run in 59 4/5. The average winning time for the Twin Spires has been 1:44 2/5; Delp's colt Seethreepeo won it Saturday in 1:46. Based on these and other comparisons, I came to the conclusion that the track over which Spectacular Bid ran was 1 1/5 seconds slower than a normal Churchill Downs track. His time of 2:02 2/5 would have been 2:01 1/5 under typical conditions.

If the times of the last eight Derby winners were adjusted in such a fashion, this is how they would compare:(TABLE) Secretariat(COLUMN)2:00 Afffirmed(COLUMN)2:01 Spectacular Bid(COLUMN)2:01 1/5 Riva Ridge(COLUMN)2:01 4/5 Seattle Slew(COLUMN)2:02 Bold Forbes(COLUMN)2:02 1/5 Foolish Pleasure(COLUMN)2:02 2/5 Cannonade(COLUMN)2:04 1/5(END TABLE)

Spectacular Bid is even better than these figures suggest; he is certainly a faster horse than last year's Triple Crown winner, Affirmed.

There seems to be some truth in Delp's contention that Spectacular Bid has changed as he has gained experience, and now needs to be pressed in order to run his best race. At least, his performances in Florida this winter were much faster than his Kentucky Derby, and were in Secretariat's class.

In the Derby, Spectacular Bid lost at least a couple of lengths because of the way jockey Ron Franklin rode him. Romanticists in the media have been saying that the often-critized jockey somehow proved his ability by winning on Saturday. In fact, the chief virtue of his performance was that he rode as if he realized his own limitations.

Spectacular Bid had a good position on the inside as the field approached the first turn at Churchill Downs, and just about any jockey would have stayed there. Saving ground on the turns is an essential part of intelligent safe-riding.

But Franklin was so fearful of getting into trouble that he swung Spectacular Bid to the far outside an kept him there all the way around the first turn. He stayed outside for the entire rest of the race.

Losing so much ground, and throwing away lengths, could have been costly if Spectacular Bid had been facing stronger competition, if Flying Paster had been as good as his West Coast press notices had suggested. But Spectacular Bid has now proven himself so superior to the other 3-year-olds that even with Franklin on his back he ought to roll through the Triple Crown series as easily as Secretariat did.