I is interesting tat someone should feel that the "Lift Factor" would be a determining factor in which sulky one thinks is the best. Virtually all of the American style speed sulkies on the market are extremely heavy in comparison to their Australasian cousins. The exception is the ZEN sulky. It is exceedingly light. This is because it is made of what we make our racing bikes out of and designed by a local bike designer and manufacturer for our olympic team and America's Cup boats.
The American style sulkies are heavy to provide extra weight and thus stability for the horse to pull. Greater stability leads to greater speed. Sitting much more solidly on the track will provide that greater speed and stability. Thus greater lift factor is a weakness factor for these sulkies. Using thicker, wider tyres is a means to reduce drag on smaller tighter tracks with these sulkies but that is again working against the value of these types of sulky which rely on their weight for stability. As I said it is the stability they provide in their weight that allows the horse improved performance. (if he has improvement in him.) The other issue with the American syle sulky used in Australasia is that they are an adaptation of the shorter, wider American version adapted to Australasian regulations...Made longer in the shafts but narrower across the beam The true aerodynamic features of these carts is virtually lost in this process. I've seen a lot of American style carts getting around Oz tracks on TV where their success is limited. The reasons I believe are twofold..
1.. The inherent ability between the shafts along with that on the seat behind.
2.. The mix and match nature of the wheel / tyre combinations affixed to these sulkies. All merican style carts are sold with fitted rim and tyre combinations for a reason but so many Oz trainers seem to operate a mix and match mentality....Likely to their detriment.