The a2z adapter will work with your horizontal dropouts, hard to explain why but i've got one on my jump bikes which has horizontal dropouts and its all good Basically it'l move with your axle as you push your wheel back and the lil' adjustable arm in the top right corner of the adapter should, with the adapter at the right angle, sit against the frame fine, stopping it from moving forward/down. There abit of a biatch to set up but i think they hold in place after very well, only problem i can imagine is backwards force occuring with trials use as there isn't anything to stop it moving backwards eg. hopping back from failed backwheel attempt and holding the backbrake to stop you flipping would put the adapter off completly. Someone with a T-lite combated this with an arm from the adapter to his mounts, think its still on the first page on bike pics or maybe second.