An emergency space blanket is a good thing to have in your pack, especially this time of year when temperatures up high and in shady canyons can be much lower than at the trailhead. If you're venturing out on a longer ride, a spare pair of gloves and socks and an extra layer are also a good idea. Pro tip: Stash some plastic baggies in your pack to use as a protective layer between your socks and shoes to keep your feet warm and dry.
It's also a good idea to carry a first aid kit in your pack. Consider High Above's Backcountry Lifeline kit, which includes all the necessities tucked into a compact zippered pouch (stash your space blanket in it as well!).
Check out this Bike Mag article for more tips and tricks on how to stay safe in the backcountry:
Being prepared on longer rides is always a good idea!