These are replacement spindles for our M/A/R/G 30 series cranks that use a 30mm spindle. Refer to the chart below to see which spindle will work for your configuration. Specifications: - Made from U.S. sourced 2024-T365 aluminum - Spindle 126.2mm total length - For 68mm/73mm bottom bracket shells - Spindle is 131.2mm total length - Compatible with White Industries cranks only - Crank arm: M30: Mountain arms - Spindle: R30 Road spindle - 1x chainline (3mm offset ring, facing inward): 46.5mm - 1x Boost chainline (0mm offset/flat ring): 49.5mm - 1x chainline (3mm offset ring flipped outward): 52.5mm - 2x chainline (measured between the 2 rings): 45mm - Q factor: 171mm - Width between inside of arms (for chainstay clearance): 144.6mm - Weight: 570g (175mm w/spindle) - BB shell widths: 68mm or 86mm - OBW (outer bearing width): 91mm (+/- 1mm) * *This is the allowable outside-to-outside measurement of your BB bearings (with seals) when they are mounted to your frame. The bearing preload collar on the crank is adjustable and can accommodate slightly wider or narrower widths (+/- 1mm) than the target number.