What you pack for a mountain bike ride is based on your preference, assessment of risk and personal style. Because Mountain Crossing rides occur in true back-country, your minimum pack should include
- Spare inner tube(s)
- Tire levers
- Hand pump
- Spare presta valve (for tubeless tires)
- Spare chain link
- Multi Tool
- Zip Ties
- Water, 1-2 liters (depending on weather)
- High-energy food to sustain you all day
- Cell phone, fully charged
Here are links with gear suggestions
https://www.rei.com/learn/expert-advice/mountain-biking-checklist.html
https://www.backcountry.com/explore/whats-in-the-pack-mountain-bike-essentials
https://www.redbull.com/gb-en/mountain-bike-essential-accessories