Just FYI for those riding Hopland on 400k, and especially first time riders. There aren't a lot of available services between Hopland and Santa Rosa, but a great resource is Jimtown and Then Sum, formerly the Jimtown Store.
It's marked on the RideWithGPS route at mile 166.5, and has a water spigot on the right side of the building when you're facing it, and has a picnic table out front with bike racks. A great place to top up and take a break. The store itself closes at 5PM, probably too early except for the fastest riders, but the water spigot is available 24 hrs.
I just got off the phone with the kind owner, Michelle, and she confirmed that they've never turned it off and it will be available.
There are plenty of other threads in this group about other stops as well, like this one: