The rear shock size of the Tallboy is 190 x 45mm. The rear hardware is 8 x 30 (bearing compatible) and the front hardware is 8 x 20. The Tallboy is compatible with the majority of air shocks except for Cane Creek and Fox Float X2 shocks.  For optimal performance, we recommend the following: • Rockshox Super Deluxe • Rockshox Deluxe • Fox Float DPX2 • Fox Float DPS