1300mm,1400mm,1500mm,there will always be someone that will have a go at bending the rules.....to eliminate the need for the stewards to be running around measuring every sulky on the course, just have each and every club install a 40mm pipe bow made to the max legal width at the horse entry,if the sulky dos`nt fit through the bow, the sulky don`nt enter the course...as simple as that.