When I start playing the horses for eternity at Heaven Downs, I will have only one small request. I hope the Great Track Superintendent will allow the racing surface to resemble the one that existed briefly at Pimlico last week.

Horseplayers who have been patronizing Pimlico regularly through this long season were unprepared for the condidtions they encountered last Monday. The track had been uniform all year, until several days of unusually heavy rain altered its composition. As moisture permeated the racing surface and then drained off toward the rail, the inside part of the track bore a resemblance to I-95.

The winning post positions in the first seven races Monday were 1-2-1-1-1-1-1. As soon as a horse got to the firmer going along the rail and took the lead, the race was virtually over. Stretch-runners in outside post positions had no chance. And when a handicapper could diagnose a situation in which the superior horse in a field also figured to take advantage of the track bias, he had found one of the surest betting opportunities in the sport.

The existence of such a strong track bias is the greatest edge a horseplayer can have. The regulars at Pimlico know how to capitalize on a bias better than players at any other track in America, but even so, there are still enough oblivious bettors in any crowd that speed-on-the-rail horses pay more than they should.

On Tuesday, a slightly faint-hearted sprinter named Cognito was trying to go a mile and one sixteenth for the first time, and handicappers anywhere else would have viewed her chances with considerable skepticism.But the Pimlico crowd knew that Cognito would get a clear lead on the rail and that the bias would carry her as far as she needed to go. To an outsider, her 8-5 odds looked ridiculously short, but bias-oriented bettors know the price was still a bargain. Cagnito won by eight.

Sometimes I think the best way to beat the horses would be to monitor every track in the coun try and hop on a plane whenever a speed-on-the-rail bias developed somewhere. Given that this is somewhat impractical, bettors must be able to recognize quickly when a bias appears at the track where they operate and capitalize on it immediately.

To identify a track bias, a bettor must watch races closely and critically. The tipoffs occur when illogical horses or habitually faint-hearted ones get to the rail and hold on much longer than they figure to. When horses with good figures try to move on the outside and look like they are running on a treadmill, that is another indicatio that a bias may exist.

In the first race at Pimlico Monday, a quitter named Fays Carl led all the way on the rail and won by a nose. That didn't necessarily mean much. In the second race, however, speedsters Cling Maroon and Calligrapher went our and battled head and head for the lead, while a well-regarded stretch runner, Ack Drone, stalked them in third place. Ack Drone was in perfect position, and when the field turned for home he swung outside and looked like a cinch to run down the two leaders. He made no headway; Calligrapher pulled away from him.

Having identified the existence of a speed-on-the-rail bias, a horseplayer's task becomes the essence of simplicity. He must forget just about everything he knows about handicapping, diagnose the horse who will get the lead on the rail and bet him blindly. When that horse happens to be the best one in the field, he should make his maximum bet, even if the odds seem to be inadequate.

The hard work a handicapper must do while a bias prevails is to watch every race closely and note every horse's position on the track.

It may be important to know for future reference that Foolish Fact raced three-wide all the way in Monday's sixth race and that his performance was much better than it looked on paper. Conversely, horses who had the bias in their favor have to be viewed with some skepticism. Cognito certainly isn't as good as her eight-length victory suggest. Neither is Leader of the Pack, who won by seven lengths Tuesday when he was the only speed horse in the field and will now be one of the favorites in today's eighth race.

The only trouble with track biases is that they are maddeningly impermanent and capitalizing on them is like trying to catch lightning in a bottle. Or, at least, that is usually the case. Maryland horseplayers wtill remember the glorious year of 1977, when a powerful spped-on-the-rail bias prevailed at Pimlico for an entire meeting. People who blindly boxed 1-2-3 in every good handicappers had to have won more money than ever before in their lives.

So when the bias reappeared on Monday and Tuesday, we could all start hoping and dreaming that we were about to start reliving 1977. That reverie lasted until the first race on Monday, when a horse named Weather Report circled the field and won going away. The order of finish by post position was 3-10-9, and all the horses on the rail faded. The bias was gone, and bettors had to start earning their money the hard way again.