Argon 18 has announced the Sum, a new road bike that is said to combine the aerodynamic efficiency of its aero road bike, the Nitrogen Pro, with the low weight of the Canadian brand’s lightweight road bike, the Gallium Pro Disc.
Argon 18 claims CFD (Computational Fluid Dynamics) analysis shows the Sum’s aero performance is “equivalent to the all-aero Nitrogen and 9 per cent faster than the Gallium Pro Disc”.
The Argon 18 Sum features a mix of kamm tail aerofoil tubes, dropped seatstays, fully hidden cable routing, a D-shaped seatpost and clearance for up to 700 x 30c tyres.
It’s a design that echoes many other recently launched aero/lightweight road bikes, such as the Merida Scultura Team, the Specialized Tarmac SL 7 and the Scott Addict (to name but a few).
Unlike many other brands, however, Argon 18 has stuck with a more traditional, non-proprietary and non-integrated cockpit for easier fit adjustments.
Cables are routed fully internally, using FSA’s ACR (Aerodynamic Cable Routing) system, but changing a stem or handlebar should still be within the remit of most amateur mechanics.
Lighter than the Sum of its parts?
Beyond its aero credentials, Argon 18 says the Sum’s tube shapes have been optimised to strip them of unnecessary weight.
According to Argon 18, a simulation of stage 6 of the 2019 Tour de France (which included ~3,500m of climbing and a summit finish on La Planche des Belle Filles) shows a claimed time saving of 75 seconds for the Sum over the brand’s previous lightweight climbing bike, the Gallium Pro Disc.
Argon 18 is offering the Sum in two different frame versions; the Sum Pro and the Sum.
Claimed weights from the Sum Pro and Sum frames are 850g and 890g, respectively, in a size medium / 54-56cm, with paint.
As a point of comparison, a size 56cm Specialized S-Works Tarmac SL7 frame is claimed to weigh 800g with paint, while a standard Tarmac SL7 frame is said to weigh 920g in the same guise.
Argon 18 Sum aero details and ride quality
According to Argon 18, the Sum’s aero features include details such as an hourglass-shaped head tube, aero-profiled fork legs that are said to “deflect air away from the down tube” and a down tube that is aerodynamically optimised for use with cycling water bottles in place.
The Sum’s slim, dropped seatstays are also said to contribute to the bike’s aerodynamic performance, as well as improving comfort.
Additionally, Argon 18 says a D-shaped seatpost, indented seat tube and slender top tube help to further increase comfort. In total, the improvement in compliance is claimed to be 30 to 35 per cent versus the Gallium Pro Disc.
Sizing and fit parameters have also been updated for better rider positioning and handling across the size range.
The Sum also gets Argon 18’s signature 3D system, which allows the upper headset bearing and cockpit to be raised without losing any steering stiffness, which the brand claims could otherwise potentially compromise handling.
| Argon 18 Sum geometry | ||||||
|---|---|---|---|---|---|---|
| Frame size | XXS / 44-46 | XS / 47-50 | S / 51-53 | M / 54-56 | L / 57-59 | XL / 60-62 |
| Seat tube height (cm) | 39.5 | 42.5 | 46 | 50.5 | 55 | 59.5 |
| Seat tube angle (degrees) | 75 | 74.5 | 74 | 73.5 | 73 | 72.5 |
| Head tube angle (degrees) | 71.2 | 72.1 | 72.7 | 72.7 | 72.7 | 73 |
| Top tube length (cm) | 50.3 | 52 | 53.8 | 55.7 | 57.8 | 60 |
| Chain stay length (cm) | 41 | 41 | 41 | 41 | 41 | 41 |
| Wheelbase (cm) | 96.7 | 97.2 | 97.5 | 99 | 100.6 | 102 |
| BB Drop (cm) | 6.9 | 7.3 | 7.7 | 7.7 | 7.7 | 7.7 |
| Head tube length 3D, 0mm (cm) | 6.9 | 8.5 | 10.1 | 12.6 | 15.2 | 18 |
| Head tube length 3D, 15mm (cm) | 8.4 | 10 | 11.6 | 14.1 | 16.7 | 19.5 |
| Head tube length 3D, 25mm (cm) | 9.4 | 11 | 12.6 | 15.1 | 17.7 | 20.5 |
| Stand over height (cm) | 67.6 | 70 | 72.7 | 76.6 | 80.4 | 84.1 |
| Stack and reach | ||||||
| Stack 3D, 0mm (cm) | 47.1 | 49.3 | 51.6 | 54 | 56.5 | 59.2 |
| Stack 3D, 15mm (cm) | 48.5 | 50.7 | 53 | 55.4 | 57.9 | 60.6 |
| Stack 3D, 25mm (cm) | 49.5 | 51.7 | 54 | 56.4 | 58.9 | 61.6 |
| Reach 3D, 0mm (cm) | 37.5 | 38.2 | 38.9 | 38.7 | 40.5 | 41.4 |
| Reach 3D, 15mm (cm) | 37 | 37.7 | 38.5 | 39.3 | 40.1 | 41 |
| Reach 3D, 25mm (cm) | 36.7 | 37.4 | 38.2 | 39 | 39.8 | 40.7 |
| Saddle Height Min (cm) | 56.5 | 59.5 | 63 | 67.5 | 72 | 76.5 |
| Saddle Height Max (cm) | 71.5 | 74.5 | 78 | 82.5 | 87 | 91.5 |
Argon 18 Sum availability, pricing and specifications
The Argon 18 Sum will be available globally in late 2022. There are two builds each in the Sum and Sum Pro ranges, as well as frameset options for the Sum Pro.
All builds announced at launch feature SRAM’s wireless eTap AXS groupsets, and either Hunt or Vision wheelsets, shod with Vittoria tyres. UK and Euro pricing is still TBC.
Argon 18 Sum Pro Force eTap
- Price: $8,250 / CAD $10,500
- Frameset: Argon 18 Sum Pro
- Drivetrain: SRAM Force eTap AXS
- Wheelset: Hunt 48 Limitless Aero Disc
- Tyres: Vittoria Corsa Competition TLR G2.0, 700 x 25c
- Handlebar: FSA SL-K SCR Compact
- Stem: FSA ACR ST-OS-160
- Saddle: Repente Prime 3.0
Argon 18 Sum Pro Rival eTap
- Price: $6,500 / CAD $ 8,350
- Frameset: Argon 18 Sum Pro
- Drivetrain: SRAM Rival eTap AXS
- Wheelset: Hunt Four Season Disc
- Tyres: Vittoria Rubino Pro, 700 x 25c
- Handlebar: FSA SL-K SCR Compact
- Stem: FSA ACR ST-OS-160
- Saddle: Repente Prime 3.0
Argon 18 Sum Pro frameset
- Price: $4,200 / CAD $ 5,999
- Frameset: Argon 18 Sum Pro
Argon 18 Sum Force eTap
- Price: $5,900 / CAD $7,350
- Frameset: Argon 18 Sum
- Drivetrain: SRAM Force eTap AXS
- Wheelset: Hunt Four Season Disc
- Tyres: Vittoria Rubino Pro, 700 x 25c
- Handlebar: FSA Energy SCR Compact
- Stem: FSA ACR ST-OS-160
- Saddle: Repente Quasar
Argon 18 Sum Rival eTap
- Price: $4,900 / CAD $ 6,250
- Frameset: Argon 18 Sum
- Drivetrain: SRAM Rival eTap AXS
- Wheelset: Vision Team 35 Disc
- Tyres: Vittoria Rubino Pro, 700 x 25c
- Handlebar: FSA Energy SCR Compact
- Stem: FSA ACR ST-OS-160
- Saddle: Repente Quasar
