18/08/2021
Maybe you will see this in HoofSearch in the future. Right now, this is a "work in progress" research paper that has been posted as a preprint for the equivalent of crowdsourced peer review.
You can download the full pdf here but REMEMBER THIS HAS NOT BEEN THROUGH THE COMPLETE PEER REVIEW PROCESS.
HoofSearch no longer indexes preprints, so this may or may not be listed there, at least until it does make it through the review process and appears in a journal. Given the team behind the project, it seems likely it may be published in the future.
Also, the data was collected on turf and an artificial racing strip, so it not technically equivalent to US racing on dirt, but still interesting.
https://www.preprints.org/manuscript/202108.0323/v1