Oval Concepts 520 Praxis Works Compact Chainset - 50 / 34T - 2 x 10 / 11 SpeedOval Concepts 520 Praxis Works Compact Chainset 50 34T 2 x 10 11 Speed The Praxis Works x Oval Concepts 520 is a cleverly designed chainset that drops your gear range a little with no discernible difference in weight, stiffness or shifting quality compared to the benchmark Shimano chainset you probably already have. This fantastic lightweight and durable chainset is exactly what you need to upgrade your ride. Spider brand model: Oval Concepts 520