I built up a Forme Calver for my son Max this week (he's in growth spurt mode so is being expensive!).
The Calver is a really well made frameset, except for the cable routing for gear cables.
The Vitus Energie VR that it replaced and my Trek Boone and Crockett all feature a full length outer from shifter to rear mech - which is awesome.
Unfortunately, where the cable enters the down tube on the Calver, only the cable inner wire goes internal through a thin plastic sleeve, to exit through an inner wire sized hole at the bottom of the down tube.
I initially set up with SRAM Slickwire cables which have been great on the other bikes, but on the Calver the shifting was sluggish.
On the recommendation of Alex Forrester (my local Calver expert), I ordered some Jagwire Road Elite Sealed Shifting Cables.
They sorted the sluggish shifting immediately.
They look like a close copy of the old Gore-Tex sealed cables which went out of production when electronic group sets became established - I was very disappointed when that happened.
The Jagwire cables are a little different though, these have a form of wet lube inside the housing liner.
Fitting is a little more fiddly than regular cables, but the instructions are well written.
If your frame has tricky cable routing which results in sluggish shifting, these are highly recommended.
I'll update the review if with time I feel differently, but so far so good.