Surly Single-Speed Kit Spacers and Lockring. Surly Single Speed Spacer Kit comes with a selection of anodized aluminum spacers so you can get a perfect chainline to complement your road track or mountain crankset. Our large-diameter stainless steel Cassette Lockring holds everything together and perfectly matches the outside diameter of the spacers. Plus it matches the machined shoulder of our single-speed cassette cogs (not included). The lockring is machined to utilize a common Shimano cassette lockring tool for installation and removal. This isnt just a mix of off-the-shelf parts; we went the extra distance to give you a kit that will provide maximum functionality durability and aesthetic value.