I bought this replacement wedge and had a helluva time with slippage until I figured out that this three piece wedge has a TOP, a middle, and a bottom. The middle piece is obvious however somehow I had the (smaller) bottom piece on top when I assembled the wedge. There was no mention of this in any forums nor in the Specialized User Manual. So if you have slippage, make sure the correct piece is on top of this three piece item.