A friction bolt assembly to frictionally engage an internal surface of a bore formed in rock strata, the assembly comprising: an elongate tube having a leading end, a trailing end and a longitudinally extending primary slot; an expander mechanism located within the tube towards the leading end and configured to apply a radial expansion force to the tube to secure the assembly to the rock strata; an elongate tendon extending longitudinally within the tube and connected at or towards a first end to the expander mechanism and at or towards a second end to a loading mechanism positioned at or towards the trailing end of the tube that by adjustment is configured to create tension in the tendon to act on the expander mechanism and provide the radial expansion force; wherein: the expander mechanism comprises: at least two radially outer wedge elements (16, 17, 44) positionally secured to the tube; and a radially inner wedge element secured to the tendon and capable of axial movement relative to the outer wedge elements (16, 17, 44) to apply the radial expansion force to the outer wedge elements (16, 17, 44); the elongate tube further comprising at least one secondary slot positioned axially at the expander mechanism and extending beyond the expander mechanism in both the axial forward and rearward directions such that the tube is capable of deforming radially at the axial position of the expander mechanism via the primary and secondary slots (26, 51) in response to axial movement of the inner wedge element and the expansion force transmitted by the outer wedge elements (16, 17, 44). an elongate tube having a leading end, a trailing end and a longitudinally extending primary slot; an expander mechanism located within the tube towards the leading end and configured to apply a radial expansion force to the tube to secure the assembly to the rock strata; an elongate tendon extending longitudinally within the tube and connected at or towards a first end to the expander mechanism and at or towards a second end to a loading mechanism positioned at or towards the trailing end of the tube that by adjustment is configured to create tension in the tendon to act on the expander mechanism and provide the radial expansion force; wherein: the expander mechanism comprises: at least two radially outer wedge elements (16, 17, 44) positionally secured to the tube; and a radially inner wedge element secured to the tendon and capable of axial movement relative to the outer wedge elements (16, 17, 44) to apply the radial expansion force to the outer wedge elements (16, 17, 44); the elongate tube further comprising at least one secondary slot positioned axially at the expander mechanism and extending beyond the expander mechanism in both the axial forward and rearward directions such that the tube is capable of deforming radially at the axial position of the expander mechanism via the primary and secondary slots (26, 51) in response to axial movement of the inner wedge element and the expansion force transmitted by the outer wedge elements (16, 17, 44). the expander mechanism comprises: at least two radially outer wedge elements (16, 17, 44) positionally secured to the tube; and a radially inner wedge element secured to the tendon and capable of axial movement relative to the outer wedge elements (16, 17, 44) to apply the radial expansion force to the outer wedge elements (16, 17, 44); at least two radially outer wedge elements (16, 17, 44) positionally secured to the tube; and a radially inner wedge element secured to the tendon and capable of axial movement relative to the outer wedge elements (16, 17, 44) to apply the radial expansion force to the outer wedge elements (16, 17, 44); the elongate tube further comprising at least one secondary slot positioned axially at the expander mechanism and extending beyond the expander mechanism in both the axial forward and rearward directions such that the tube is capable of deforming radially at the axial position of the expander mechanism via the primary and secondary slots (26, 51) in response to axial movement of the inner wedge element and the expansion force transmitted by the outer wedge elements (16, 17, 44).