Nike Men's ACG Ultrafly "Hyper Crimson"

The Nike ACG Ultrafly refines everything that made the original a standout, delivering a smoother, more controlled ride for long days and big miles on the trail. Built for runners who want efficiency without sacrificing confidence on technical terrain, it’s a shoe designed to keep you moving strongly as fatigue sets in.

At its core is springy ZoomX foam, Nike’s most responsive midsole material, offering exceptional energy return with a stable platform underfoot. The foam is unwrapped at the heel to enhance responsiveness while maintaining control on uneven ground. A full-length carbon-fibre plate adds propulsion and protection, tuned to be slightly softer than the original Ultrafly for improved flexibility and trail feel.

The breathable mesh upper is lightweight, durable and designed to drain water quickly—ideal for wet trails, stream crossings and unpredictable conditions. Underfoot, a Vibram® Megagrip outsole delivers reliable traction and durability, helping reduce weight without compromising grip as the miles add up.

A fast, efficient trail shoe built for racing and long-distance efforts when performance matters most.

• ZoomX Foam: Ultra-responsive ZoomX foam midsole delivers Nike's highest energy return with a stable feel for the trail. The foam is 'unwrapped' in the heel for even better responsiveness.
• Breathable Mesh Upper: Don't worry about puddles or streams—the upper is made for water drainage. It's also lightweight, durable and breathable.
• More Flexibility: Tackle technical terrain with the full-length carbon-fibre plate. We reduced the stiffness compared to the original Ultrafly for better control on the trails.
• Enhanced Grip: Go the distance with Vibram® Megagrip outsole. It's designed to give you durability and enhanced grip on wet terrain.
• Colourway: Hyper Crimson/White-Total Orange
• Product Code: HF5668-801

Technical Specifications:
Intended Use: Trail Running / Trail Racing
Support: Neutral
Width: Regular
Weight: Approx 290g 
Drop: 8.5mm (37mm heel vs 28.5mm toe)
Lug Depth: 3mm

All sizes displayed on our website are UK sizes.

We are currently working on measurements for apparel and accessories so please bear with us.

In the meantime, for footwear, please refer to the sizing guide here. However, if you require any additional advice on sizing, please contact us.

Worldwide shipping, domestic shipping in the UK, and in-store collection is available.

You can find all relevant shipping information here.

We have a 28-day return policy, which means you have 28 days after receiving your item to request a return. 

To be eligible for a return, your item must be in the same condition that you received it, unworn or unused, with tags, and in its original packaging. You’ll also need the receipt or proof of purchase.