We tame complexity when we can. But in our quest for simplicity, a 1x10 rarely works perfectly without the addition of a chain guide like this ethirteen XCX Chain Guide. The truth is that the front derailleur does a noble job of keeping the chain in line over your chainrings as you pedal through rough sections of trail. When you get rid of it, you'll want a guide to take its place. The XCX Chain guide functions in the same way, though you set it up once and leave it alone. It's perfect for race bikes, or any other bikes for that matter that rely on a drivetrain consisting of a single chainring and a multi speed cassetterear derailleur. The plastic slider, or wearplate, acts to keep the chain from dropping off either side of the chainring, no matter how choppy the terrain. And just like the variety of front derailleur mounting options, ethirteen builds the XCX Chain guide to fit just about anything. It's available with four mounting configurations. All options will accommodate chainrings from 32 to 42t and are available in Black. 1 Bottom Bracket: A 7075 aluminum backing plate functions as the required spacer between your drive side external bearing cup and the bottom bracket shell. This mount is a great option for carbon bikes with odd seat tube dimensions, or if you switch bikes every year. It will always fit as long as the bottom bracket is of the threaded external bearing type. This option works with a 49mm chainline. 2 Direct Mount: This fits frames that use a Shimano high direct mount on the seat tube. This type includes wave washers to adjust the chainline from 50 53mm. 3 E Type: This fits frames that have a E Type, or more appropriately a two bolt low direct mount on the seat tube. This type includes wave washers to adjust the chainline from 50 53mm. 4 Seat Tube High: This option clamps around the seat tube above the slider, with the same fit as a high clamp front derailleur. If you have a pressfit bottom bracket of some sort, this would work nicely...