Wheels Manufacturing SOLO-SPEED Cog - 19t Fits SOLO-SPLINE SOLO-XD kits BlueWheels Manufacturing SOLO XD Cog 19t Blue. Wheels Mfg. SOLO XD and SOLO SPLINE Single Speed cogs are constructed with high end 7075 aluminum and designed with narrow to wide alternating tooth pattern allowing for superior chain retention. Cogs are optimized for use with Wheels Mfg. SOLO XD XD XDR and SOLO SPLINE Single Speed Conversion kit carrier systems only. Crafted with high end 7075 aluminum for light weight and extreme durability Cogs are