Vs the O1, the R1 chassis has a larger radius to provide more support and stability when pushing off. The smaller radius in the rear allows to still get the smoothness in turns and longer wheel contact with the surface. It offers 4 different interchangeable radius inserts so you can customize according to personal preference. The O1 has a straight 4 ft radius. The R1 comes with the combinations: 5 (rear)-8 (front) ft, 8-8ft, 5-15ft and 8-15ft. //Per, Inventor