I have a 2017 BMC Roadmachine 01 with the custom D-shaped carbon seatpost. Recently the longer of the two bolts that go vertically thru the top of the seatpost into the clamps that hold the rails of the saddle snapped in half. I was able to easily remove the bolt and replace temporarily with a hardware store M5 version (and little o-ring) that is close but not quite the same. Local bike shop contacted BMC and they will only sell me the complete seat post (with clamp and bolts). I scoured the internet for this bolt and cannot find it. I think it would be called something like "M5 Socket Cap Head 45 mm length - half thread. But the part is non-standard because of the taper from the cylindrical head to the bolt shaft that allows it to fit snugly into the carbon cavity recess of the seatpost. I have attached a picture. So has anyone else experienced this and more importantly have any idea how to find a replacement bolt? Thanks!