Quarq Dfour Fit Problem
@Victor this can be made to work.

The new crank has a GXP interface spindle, you can notice that by a notch before NDS arm splines start, which serves as a stops against inner bearing race, and the fact that splines are on non-drive side (SRAM BB30 splines are on drive-side). Since GXP is a Truvativ/SRAM variation on 24mm spindle, it should fit everywhere Shimano 24mm Hollowtech II fits. The spindle length is no problem, BB30 bottom bracket shells are the narrowest (68mm, FC-6800 is designed around 86mm bearings stance), so with the right bottom bracket you could install almost any crank, so all you need is a BB30 to GXP bottom bracket.