A few comments, even though this is deep into the thread.

- The BMC frame looks significantly worse inside than a Cannondale frame and a Giant Defy I saw in person. The section where the top tube and head tube join looks like my 1st grader built it.

- I have 0 idea if the inside at all affects performance or reliability. If it doesnt, then it just isnt important.

- The fact that other frames are able to be much cleaner inside shows its possible and if the bikes cost comparable amounts, then comparable quality is expected.

- I find it deliciously ironic that the OP has made unsubstantiated claims about quality and declared unknowns to be known at various points in the thread, all while hedging that he hasnt.



Carry on with the Engineering speak.