information is available for spoke length calculationsChris Jeggo wrote: ↑18 Oct 2021, 5:54pm To get the rim in the same plane as the central plane of the bike frame the asymmetry of the dishing has to cancel out the asymmetry of the dropouts. Where the hub flanges finish up depends on the choice of hub. It therefore follows that the symmetry of the spoking depends on the choice of hub.
There are two desirable symmetries, the rim with respect to (wrt) the bike frame, and the rim wrt the hub flanges. If the frame builder knows the asymmetry of the hub flanges wrt the locknuts then he can build the frame to match, and everything will be lovely. Clearly ICE have designed their frame on the assumption that the central plane of the hub flanges is 6mm from the central plane of the locknut faces.
It must be at least 30 years ago that Orbit were building some frames with the dropouts 4mm to the right; that was a compromise between chainline and completely eliminating dish. I guess with a recumbent the chain is so long that chainline is less important, and they have gone for eliminating dish.
Even so, I think that its an unsound assumption that if you put the rim equidistant between the flanges then the rim will be on the bike's centreline, although it probably matters less on a long wheelbase trike than on a short wheelbase bike.