+1 on the hydration pack -- water bottles on the bike frame tend to get dirty.
In the "just in case" category, you should always have ID and your health insurance information. And a cell phone with a charged battery, though it's possible you'll be in an area with limited coverage. If you're riding alone, make sure someone knows where you'll be. I always keep some adhesive bandages in my bike bag, too, including some large ones.
Have fun!
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles