The most direct route from Hilo (east side of island) to Kona (west side) is via Saddle Rd/Rte 200..a 65 mile bisect of the island which climbs to 6700' along the way. A unique cycling experience to say the least.
Saddle Rd has been under a realignment project for several years and is nearly complete but at the moment, between miles 8-12, it's an active construction site with gravel, mud, one-way traffic, heavy machinery, and more gravel and mud. Passable on 700x24 tires but just barely. If not for Gatorskins I would have walked it due to threat of puncture from the sharp lava gravel road base. Otherwise all good on Saddle Rd.
This was March 25, 2017. Project appears to be another couple of months from completion.
Anyway, maybe this info will help someone.