As the largest option in Gregory's mountain biking-specific collection, the Women's Amasa 14 Hydration Backpack is your best shot at hitting longer trails for day-long trips. It can hold hydration reservoirs as large as three liters, and there's still plenty of space for lunch, layers, and a small bike shop's worth of tools. Gregory's Shift RS suspension system includes light foam with spacer mesh that assures the utmost ventilation, and the padded waist belt moves with your hips for long-lasting comfort.