All DeMonchaux frames Bottom-Bracket shell are precision tapped and faced.
It is the part that hold the bearings which turns around the Bottom-Bracket axle, the axle is spinning via the crank arms and the pedals.
Nonetheless rolling resistance, efficient power output and comfort are more important qualities.
Indeed, what the point of having a lightweight bike if the rider energy is not efficiently transferred into the rear wheel?
On a bicycle “Power Loss” means the rider energy is partly lost before it reach the rear wheel.
Having some “power loss” create a drag effect that can be compared to riding with some headwind.
With an efficient power output, the rider will ride faster and/or longer than on a bicycle that is not optimum.
All DeMonchaux frames Bottom-Bracket shell are tapped and faced (headset headtube too) to ensure perfect bearings alignment and optimum efficient rider energy output.