I've searched and searched, and no one else seems to have this problem, or atleast think of it as a potentional problem.
So I've just got some Sram RED cranks and a Hope (Ceramic) Road BB, with the Hope GXP conversion-set. Now what the GXP-conversion set does, is that it changes the way the crankset mounts to the BB. There are two "rings" that pressfit mount on either side of the non-drive side BB bearing. A: Making the ID of the bearing smaller to fit the Sram crankset axle, and B: Taking all the pressure of the non-drive side bearing when installing the non-drive side crankarm as it presses only against the outer "ring", which in turn presses against the inner "ring", which in turn presses against the ridge on the Sram crankset axle. There by in theory putting all of the preload pressure on the ridge of the axle, not on the BB bearing. This way the drive-side crankarm doesn't even touch the drive-side bearing.
That's fine in theory, but I have two potential problems that I just can't figure out. For one the GXP-conversion "rings" are about 4mm wide together, in the parts that sit outside of the bearing, leaving me very little visible crankset axle to engage the non-drive side crankarm on. With a normal Sram GXP BB the crankarm will sit about 16mm in on the crankarm, I've got 12mm showing... It's tight, for now, but I haven't ridden it yet and I fear there will develop some play, and ruin the axle splines and non-drive side crankarms splines.
Second problem, and the main one. As I fully tighten the non-drive side crank, there really is some serious drag from the BB (I get about 2 full revolutions from a hard spin on the crank). If I loosen the crank even slightly the drag is gone (5-6 revolutions from a hard spin on the crank). In theory, with the BB/Crankset interface of the Hope BB, this should not be possible????
The frame has been used with a Shimano setup earlier, which worked fine and very little drag on the BB, and the frame was faced by a good mechanic with the proper tools prior to mouting the Hope BB / Sram RED cranks. Everything has been mounted to the proper instructions and I've watched the Hope Tech YouTube video which explains the procedure in the same way...
Has anyone else had issues like this? Is the shortage of visible axle gonna be a problem, is the (hopefully initial) drag normal with a ceramic BB? And why does tightening the crankarm give more drag when in theory it shouldn't even be pushing on the bearing?