The base of the stand is not designed for pedals to be fixed down, they just sit on the base. Unless you have the Mad Catz wheel which can be fixed down.
So far the following wheels have been tested and are compatible - - Logitech G25, G27 and G29 - Logitech Driving Force GT - Logitech Drive FX - Thrustmaster T80/T100/T150/T300RS/TX/TMX/458 Spider - Fanatec CSR - Ferrari 458 Italia for Xbox360 - Ferrari GT - Hori RWA/RWO
IT IS NOT SUITABLE FOR THE HORI WHEELS AS THEY USE SUCTION PADS RATHER THAN A CLAMP