Well thankfully a rebel alliance of manufacturers have brought this new standard to our galaxy
Yay, the death star of press fit has been vanquished.
So metal bottom bracket shell= easy to thread.
But carbon shell= Can you create a carbon thread, or are we always talking about a threaded metal insert into the carbon?
You could create a carbon thread if you started out with that intention (it’d be hard but possible, maybe not with a standard thread pitch/profile), but if you cut a thread into carbon you’ll end up cutting the fibers and the threads will be very weak.
Bonded insert is not that bad, plenty of aluminum aerospace components are actually glued together (as are Shimano fancy chain rings) plenty of bound areas with a PF 30 sized shell too.
(not that I care, BSA steel is still pretty real ATMO)
Thanks dafrog, makes sense. Although the alloy sleeve in carbon has been known to delaminate.
And increased weight too
Has anyone figured out now to mould threads into carbon yet?
google says no
or more accurately searching for “carbon threads” gets lots of hits on alibaba for carbon fibres (or thread) not holes for screwing things into.
Unfortunately the linear nature of carbon fibre does not lend its self to beeing threaded.
Carbon is strongest in a straight line and if molded creates weak points at the right angles in the thread and if threads are cut into the carbon the strength is lost also…
Bonded Ti insert is by far the best method.