The HEIR Direct Mount Crank offers direct mount crank versatility and performance, in crank lengths that are optimized for young riders. Features Stiff and light cold forged design. Compatible with 3-bolt direct mount chain rings. Specifications COMPONENT WEIGHT HEIR 110mm Direct Mount Crank 454 grams HEIR 130mm Direct Mount Crank 470 grams HEIR 152mm Direct Mount Crank 509 grams Chain Ring - 28t 58 grams Chain Ring - 30t 68 grams Bottom Bracket 138 grams DIMENSION 110mm 130mm 152mm Crank Arm Length 110mm 130mm 152mm Q Factor 151mm 170mm 170mm Spindle Diameter 24mm 24mm 24mm Determining Chain Ring Offset: If your bike has 148mm rear spacing (Boost), choose 3mm chain ring offset If your bike has 135mm or 142mm rear spacing, choose 6mm chain ring offset (most kids bikes fall under this category). Assembly Instructions