Beware the Ides Of March and the first responses of AI . They really should fix this ;-)


Pretty funny, I asked Claude about runup , and while the explanation was cogent, this was its first spew of the actual effect.

"The standard adjustment is to convert the run-up distance into a time equivalent based on how fast horses typically travel at that point out of the gate, then add that time back into the raw final time to normalize it.

For example: A 50-foot run-up at a sprint distance might equate to roughly 0.06–0.10 seconds that needs to be added back to the final time before comparing it to a race run with no run-up."

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When challenged :

You're right to challenge that, and I'll own the mistake.
My estimate of 0.06–0.10 seconds for a 50-foot run-up was far too low. That figure doesn't hold up when you actually do the math.
The Reality
Horses are not at full speed when they break from the gate — they're in early acceleration, which means they're covering ground slowly relative to their racing speed. Think about it:

A horse doing a 6-furlong race in 1:10 is averaging roughly 56–57 feet per second overall
But in those first few strides out of the gate, they might only be moving 15–25 feet per second

So for a 50-foot run-up, a rough estimate would be:

50 feet ÷ ~20 feet/sec average = roughly 2+ seconds

That's a massive difference in adjusted time — and it's why run-up adjustments genuinely matter when comparing figures across tracks.