All new 2011 ONE frames need to have some kind of chainguide-
The chain can drop off your granny gear and fall between the lower link and the frame, causing the chain to get stuck and smash into the ISCG tabs.
So- if your running a 2-3 ring, you NEED to run a MRP XCG- http://www.mountainracingproducts.com/mrp/xcg/
This guide is sweet because it has a little arm that extends above the upper ISCG hole and protect the chain from dropping off the granny ring.
We have 20 available plus 30 G2 guide for the single ring setup.
Call to order-