Route up from Itsukaichi has been improved and is now good for road bikes although there are still many potholes and gravelly areas so descending towards Itsukaichi needs care. Route from Hachiouji is quite smooth, has some great views especially near the Iriyama Tunnel but watch out for rock slides. Both have some steep parts but are doable with a wide range of gears.
Gates are generally shut on both sides and you are asked to refrain from going up - cyclists don't seem to get stopped so I assume it's more for motorbikes etc.