I learned about Peachy Canyon from Bestrides, and rode it last weekend (April 7, 2019). Very nice ride, with a fantastic descent on the west side of the road. We rode it on a Sunday that had perfect weather, and there wasn’t much traffic, despite the fact that there are several wineries on the road. I counted 17 cars in the first 45 minutes of the ride. 

It’s a 21-mile round trip from Paso Robles to the end of the road, and I added miles by doing the first part again (the eastern section, closer to Paso) after returning. Per Strava, my grand total was 31.91mi, 2:38:02 elapsed time, and 3,935ft elevation.