Hydration vests for AC100: picks + setup that won’t fail late
Your hydration system needs to work when you’re tired and moving fast through aid stations. This page gives you a simple vest + flask setup, how to fit it so it doesn’t bounce, and what to carry so you stay consistent.
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Related: AC100 Gear · AC100 Shoes · AC100 Guide
Quick picks
Best all-around: Salomon ADV Skin 12
Stable fit, easy access pockets, and a layout that works when you’re tired. A very safe default for long ultras.
Check price →More structure / storage
If you want a vest that feels “locked in” with extra organization for long solo runs and big training days.
Suggested models: Ultimate Direction Ultra Vest, Nathan Pinnacle.
Minimal race-day option
If you prefer a lighter feel and you know your kit is dialed. Great when you’re efficient at aid stations.
Suggested models: Salomon Sense Pro, lightweight UD/Nathan options.
Fit rules (so it doesn’t bounce on descents)
- Snug, not tight: it should stay stable without restricting breathing.
- Load it like race day: try it with flasks full, phone, calories, light shell.
- Downhill test: if it shifts on descents, it will annoy you at mile 70.
- Easy access: you should reach flasks and calories without removing the vest.
Soft flasks vs bladder (simple decision)
Soft flasks
- Fast refills at aid stations
- Easy to track what you’ve consumed
- Usually the simplest AC100 setup
Bladder
- Great for longer dry stretches if you prefer it
- Harder to refill quickly
- Can hide dehydration if you’re not careful
If you’re unsure: start with flasks. Add a bladder only if you have a clear reason.
What to carry in the vest (race-ready)
Front pockets (always)
- Calories for the next 60–90 minutes
- Electrolytes you actually use
- Small trash pocket (wrappers)
Rear storage (as needed)
- Light shell or arm sleeves
- Small first-aid / blister item
- Backup light (mandatory)
Heat management
- Cap / buff
- Sunscreen stick
- Small packet wipes (salt + grime)
FAQ
How do I pick size if I’m between sizes?
Pick the size that stays stable when loaded. A vest that bounces becomes a problem late-race.
Do I need poles compatibility?
Only if you plan to use poles. If yes, make sure your vest supports quick stow without removing the pack.