Key Features of the Eye BMX 4130 Bike Frameset: 13.5-14" chainstay length. 74.5 Head tube angle on the 21" (75 on the 21.25"). 71 Seat tube angle. 11.5" Bottom bracket height. 25.4 Seat post (Animal Post included, and recommended). You have to run a wedge style post with this frame. (Animal, Stolen, etc. ) 14mm CNC'd drops. All brake studs, tabs, and gyro tabs are removable, for a clean brakeless look. .035 - .049 tubing throughout, with a few butted areas where it is needed. 21.25" weighs 4lb 9oz. Obviously the smaller sizes are just under that weight.