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The Argon 18 Nitrogen 105 Di2 Bike is the Montreal brand's most complete answer to the question of what a modern aero road bike should actually be — not a wind-tunnel exercise optimized for conditions that don't exist on real roads, but a machine built for speed, lightness, fit, and ride quality in the conditions where cyclists actually train and race. The Nitrogen platform distills years of aerodynamic research from Argon 18's track and triathlon programs into a road frame that's fast without sacrificing the handling precision that makes a bike worth riding hard.

The carbon frame is built using Argon 18's Elite Level Layup — the same engineering approach used on their Pro-level bikes, applied to Elite-grade carbon fiber. Every aerodynamic decision on the Nitrogen has a structural rationale: the Flow-Optimized Headtube uses an extended volume and angled edge to reduce drag at the front of the bike; the dropped horizontal seat stays — a design borrowed directly from Argon 18's Electron Pro TKO track bike and E119 triathlon machine — clean up airflow around the rear wheel; an oversized bottom bracket area maximizes power transfer; and the aerodynamic carbon seatpost and fully integrated internal cable routing eliminate external snag points that create drag and visual clutter. The result is a frame that reads as fast because it is fast, with no features included purely for appearance.

The 105 Di2 build equips this platform with Shimano's fully electronic 12-speed groupset — reliable, precise wireless-adjacent shifting via junction box and internal wiring, with a 52/36T crankset and 11-34T cassette that handles everything from flat road sprints to sustained climbs. Braking comes from Shimano 105 R7170 hydraulic disc with Shimano CL700 rotors (160mm front, 140mm rear). Completing the package are the ATTEN L42 wheels — Argon 18's in-house 42mm deep carbon wheelset — and Vittoria Corsa N.EXT TLR 700×30 tires running tubeless-ready, giving the Nitrogen a fast, race-capable setup straight out of the box. The ATTEN CHB-01 integrated aero handlebar serves as both cockpit and computer mount, keeping the front end clean and aerodynamically consistent with the rest of the frame.

Design Benefits

1. Aero Design with Real-World Intent: Argon 18 engineered the Nitrogen for performance in actual riding conditions, not just controlled wind-tunnel testing. The Flow-Optimized Headtube, dropped horizontal seat stays, aerodynamic seatpost, and integrated bottle cage mounts all reduce drag without requiring riders to sacrifice handling or comfort. This is aero design that works at group ride pace, not just on a velodrome.
2. Argon Fit System: Each frame size in the Nitrogen lineup uses its own size-specific geometry rather than scaled-up or scaled-down versions of a single template. The six sizes — XXS through XL, covering riders from 44cm to 62cm height ranges — are each tuned for optimal positioning and handling at that size. For smaller riders in particular, this approach delivers handling precision that scaled geometry can't match.
3. Shimano 105 Di2 Electronic Shifting: The full Di2 groupset brings electronic precision to the 105 tier — clean actuation, consistent shift quality under load, and the ability to fine-tune shift behavior through Shimano's E-TUBE app. The 52/36T × 11-34T gearing range handles diverse terrain, and hydraulic disc braking with 160mm front / 140mm rear rotors delivers reliable, modulated stopping power in all conditions.
4. ATTEN L42 Wheels and Integrated Cockpit: The ATTEN L42 wheels (42mm rim depth) are Argon 18's own design, engineered to pair aerodynamically with the Nitrogen frame as a system rather than as an afterthought. The ATTEN CHB-01 aero handlebar serves as a fully integrated cockpit with built-in computer mount, keeping the front end clean and aerodynamically consistent from stem to bar drops.
5. Tubeless-Ready Setup: The Vittoria Corsa N.EXT TLR tires at 700×30 pair with the ATTEN L42 rims for a tubeless-ready configuration. Running tubeless at lower pressures reduces rolling resistance, improves grip, and protects against pinch flats — meaningful advantages for training rides and race days alike on roads that aren't perfectly smooth.

Final Take

The Argon 18 Nitrogen 105 Di2 is a well-considered aero road bike from a brand that does the engineering work carefully and quietly. At $5,999 it delivers full electronic Shimano shifting, a purpose-built aero carbon frame with a genuine fit system, an integrated cockpit, carbon wheels, and tubeless-ready tires — a complete package that doesn't require immediate upgrades to perform. For riders who want an aero road bike that's as thoughtful about how it fits as how fast it goes, the Nitrogen makes a strong case.