Using not only rider feedback experience and knowledge we39ve taken tread design a step further by manipulating each knob of the fast trak with fe analysis the result is less rolling resistance more traction when you need it all in a lightweight package adaptive tread technology for competitive xc riderscasing 120 tpibead foldablebutyl wrapped bead 2bliss readycompound 60a26quot x 20 psi 35 65