Originally Posted by
CACycling
By the time you factor in the weight of the insert and the epoxy, is there still a significant weight savings? Seems like a lot of downside for what seems like little, if any, reduction in weight. Or is there some other advantage?
The advantage is some degree of immunity to user error in overtightening the expander and damaging the steerer (it does happen). There's alse a bit of a safety net effect in having a sleeve transition from the stem to deep below the upper HS bearing. If the carbon steerer should crack below the stem(which they've been known to do in rough service) the steel tube which is more ductile could hold together long enough to prevent a crash.
OTOH, this system might just be a clever idea Alpha-Q came up with to limit resale of used forks.