BMC’s new Kaius is an ultra-light, aerodynamic gravel bike built to race

BMC has joined the likes of Cannondale with its SuperSix EVO SE, Cervélo’s Áspero 5 and Specialized’s S-Works Crux in producing a lightweight, aero and stripped-down race bike for gravel riding.

The all-new Kaius has little in common with the brand's tech-laden, suspension-equipped URS LT gravel bike. Instead, its design bears more resemblance to the brand's all-round race bike, the Teammachine SLR.

Lightness as standard

The Kaius was conceived to be a road-race-light gravel bike from the outset.

The frame and fork design share plenty of tube shapes with the brand’s road-going Teammachine SLR; the sculpted angular head tube, oversized down tube and tapered top tube come straight from the SLR’s playbook.

At the rear, a cutaway seat tube keeps the back end tight for quick handling and the thin seatstays are broadly spaced to allow for 44mm wide tyres to be fitted.

BMC tells us the gravel-tuned frame uses a broad combination of carbon fibre specifications throughout.

There’s an emphasis on high-modulus fibres concentrated in areas that require stiffness (such as the head tube and bottom bracket), and more compliant layups are used elsewhere to help reduce vibrations.

The lightweight Kaius frame has also been reinforced and protected in areas where it will be exposed to rock strikes and shocks over rough surfaces.

Despite all the reinforcements, BMC has kept the weight respectably low, with the frame having a claimed weight of just 910g and the fork a further 400g.

Completing the frame module is a 160g seatpost and an aero-optimised cockpit, adding up to another 315g. The total weight is 1,785g in a size 56cm.

Aero for dirt

The ICS Carbon Aero cockpit found on the range-topping Kaius 01 One follows the same design cues as the brand’s road-going ICS systems. That said, the bar shape is quite radically different.

The top section of the bar is just 360mm wide, in keeping with the current trend towards narrower widths. The bar then flares out at a 12.5-degree angle, spreading the width to 420mm at the drops.

The aero is further enhanced by the inclusion of BMC’s Aerocore bottle cages (similar to those found on the Timemachine and Teammachine).

These cages integrate smoothly with the frame, the down tube cage and bottle designed to smooth the airflow in unison with the second upright bottle and cage.

BMC doesn’t make any aero-saving claims around the Kaius. It says this is because it's the brand’s first foray into this type of gravel bike.

All models come with aero-optimed wheels. Zipp’s highly rated 303 Firecrests are specced on the 01 One, the Zipp 303S on the 01 Two and BMC’s own CRD-400 40mm carbon tubeless wheels on the the 01 Three.

Gravel geometry

BMC's goal with the Kaius was to make a bike that's fast on gravel roads, with the design team looking towards road bike geometry and adapting it for gravel.

That means a longer reach to shift the front wheel forwards for improved stability and traction, while at the same time keeping the stem length compact to maintain responsive handling.

Comparing the Kaius to the URS, the Kaius has a lower stack and longer reach for an equivalent size. The URS comes in only four sizes (S, M, L, XL), whereas the Kaius comes in six (47, 51, 54, 56, 58, 61cm).

BMC has also steepened the head angle of the Kaius to 72 degrees compared to the URS’s 74. The wheelbase on the Kaius is also significantly shorter – a 56cm bike comes in at 1,026mm compared to the medium URS LT’s 1,064mm.

With ICS stem

With ICS2 stem

On paper, this should add up to a bike that’s fast on gravel and no slouch on the road. With the bike’s low frame module weight, the Kaius could make a formidable do-it-all, single bike option.

The frame can be paired with 1x or 2x drivetrains, also offers dropper post compatibility and can be used with BMC’s new MTT suspension stem.

BMC Kaius range details

The Kaius launches with three models: the range-topping 01 One with SRAM Red AXS XPLR, the 01 Two with Force AXS XPLR and the 01 Three with Rival XPLR.

BMC Kaius 01 One

• Prices: €11,499, $11,999, CHF11,999, £11,350
• Frame: Kaius 01 Premium carbon
• Fork: Kaius 01 Premium carbon
• Seatpost: Kaius 01 Premium carbon D-shaped 15mm offset
• Handlebar: ICS Carbon Aero, one-piece full-carbon cockpit
• Stem: ICS Carbon Aero, one-piece full-carbon cockpit
• Saddle: Fizik Vento Argo 00
• Crankset: SRAM Red AXS XPLR 44t
• Cassette: SRAM Force AXS XPLR XG1271 10-44t
• Chain: SRAM Red 12-speed
• Bottom bracket: SRAM DUB PF86
• Front derailleur: N/A
• Rear derailleur: SRAM Red AXS XPLR
• Shifters: SRAM Red AXS HRD
• Brakes: SRAM Red AXS HRD,Centreline rotors (160/160)
• Wheels: Zipp 303 Firecrest
• Tyres: Pirelli Cinturato Gravel H, 40mm

BMC Kaius 01 Two

• Prices: €8,499, $8,999, CHF 8,999, £8,350
• Frame: Kaius 01 Premium carbon
• Fork: Kaius 01 Premium carbon
• Seatpost: Kaius 01 Premium carbon D-shaped 15mm offset
• Handlebar: BMC RCB01 carbon
• Stem: BMC ICS2
• Saddle: Fizik Vento Argo R3
• Crankset: SRAM Force AXS Wide 43-30t
• Cassette: SRAM Force AXS XG1270 10-36t
• Chain: SRAM Red 12-speed
• Bottom bracket: SRAM DUB PF86
• Front derailleur: SRAM Force eTap AXS Wide
• Rear derailleur: SRAM Force eTap AXS Wide
• Shifters: SRAM Force eTap AXS HRD
• Brakes: SRAM Force eTap AXS HRD, Centreline X rotors (160/160)
• Wheels: Zipp 303S
• Tyres: Pirelli Cinturato Gravel H, 40mm

BMC Kaius 01 Three

• Prices: €5,499, $5,999, £5,699
• Frame: Kaius 01 Premium carbon
• Fork: Kaius 01 Premium carbon
• Seatpost: Kaius 01 Premium carbon D-shaped 15mm offset
• Handlebar: BMC RCB01 carbon
• Stem: BMC ICS2
• Saddle: Fizik Vento Argo R5
• Crankset: SRAM Rival AXS Wide 43-30t
• Cassette: SRAM Rival AXS XG1250 10-36t
• Chain: SRAM Rival 12-speed
• Bottom bracket: SRAM DUB PF86
• Front derailleur: SRAM Rival eTap AXS Wide
• Rear derailleur: SRAM Rival eTap AXS Wide
• Shifters: SRAM Rival eTap AXS HRD
• Brakes: SRAM Rival eTap AXS HRD,Paceline rotors (160/160)
• Wheels: CRD-400, 40mm, Tubeless ready
• Tyres: Pirelli Cinturato Gravel H, 40mm