There was an interesting post which I only picked up after the Derby from Simon Rowlands regarding the stride length of the Derby winner pre Derby run. At around 26+ it is very high, only 6.7% of horses have registered a stride length in excess of 26. There would have been two ways of looking at this pre Derby, firstly does it have any significance for him staying but perhaps more importantly will he handle the track. Many would have assumed no based on such a high stride length as its generally thought that the undulations of Epsom do not suit the big strider. This set me pondering over the TPD data and whether stride length as an indicator of size has any bearing on track preference. After digging around I felt that there is simply too little data yet to really start making predictions but what I felt I could do at this early stage in the emerging life cycle of TPD data is whether a big horse holds any betting advantage over small ones.

Calculating the average stride length of horses by track/distance/going/class then enabled me to compile a list of horses that posted a placed run that was greater than the average for the race they were running in. These would be deemed large horses although clearly those just above average are more average than large. Similarly those below average were deemed small.

How would we have got along betting them blindly in their following races.

Large horses produced 2783 bets and a ROI of -4.73% to BFSP
Small horses produced 3179 bets and a ROI of -8.9% to BFSP

This difference was more pronounced when looking at bet runs only in handicappers

Large horses ROI -1.73%
Small horses ROI -8.36%

That’s a huge difference if it holds up and one wonders if handicapped of the future may allocate penalties based on horse size ?.