The HD130 chainring adapter can be used to replace the standard steel chainwheel that comes with the HD. If you want to run a higher end 130BCD chainwheel. Generally, a 38T to 55T chainwheel with 130BCD would be ideal to use. You can also use the BBS-HD Chainring Spacer to make incremental corrections to the chain line. Manufactured in the US by California E-bikes using 6061 aluminium and CNC machined with a black anodised finished.