not necessarily, the clamp compresses its full width, under pressure from the bolt and barrel nut, there are single bolt ones sold..
Seems the angled slot, to not align with the slot in the frame tube , Is that Tube Not Round?
is a common feature of clamps that are to be used on CF frames..
more accurately the seat tube ID matches the OD of the seat post, the better..
....
Last edited by fietsbob; 10-06-17 at 11:39 AM.