BMC Kaius ONE 01

£11,350 The flagship model of the new Kaius is an ultralight, racing, aero superbike for… gravel

The Kaius was conceived to be a road-race-light gravel machine and the frame and fork design share plenty of tube shapes with the brand’s roadgoing Teammachine SLR (see the sculpted angular headtube, oversized down-tube and tapering top-tube for instance).

01 Clear thinking

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, matching the fork’s generous tyre clearance.

02 Super stiff

The head-tube and bottom-bracket areas have a stiffer carbon-fibre construction while more compliant areas elsewhere help reduce vibrations. The lightweight frame has also been reinforced and protected in areas that are exposed to rock strikes and shocks. The weight is still respectably low, though, with the frame having a claimed weight of just 910g, and the fork a further 400g. The seatpost weighs 160g, and an aero-optimised cockpit 315g, totalling 1,785g in a size 56cm. The bike you see here is an impressive 7.72kg (58cm).

03 Aero for gravel

The one-piece ICS Carbon Aero cockpit follows the same design cues as the brand’s road-going ICS systems, but the bar shape is radically different. The top section of the bar is just 360mm wide, but the drops flare out at a 12.5 ˚ angle to a width of 420mm to add stability. BMC’s Aerocore bottle cages integrate with the frame to smooth the airflow and Zipp’s Firecrest 303 wheels also boost aerodynamic efficiency.

04 Stable speed

There’s a longer reach than on a pure road-race bike to add stability and traction, but the stem length is compact for responsive handling. Compared to the brand’s Medium URS LT gravel bike, the head angle is a steeper 72 ˚ and the stack is lower; the wheelbase is also shorter: a 56cm bike comes in at 1,026mm. All this makes it super speedy.

05 Geared up

SRAM’s latest wireless RED AXS XPLR 1x drivetrain combines a raceready 44-tooth chainring with the wide 10-44 cassette. SRAM RED hydraulic brakes with 160mm disc rotors help this speedy bike stop fast.

“The lightweight frame has also been reinforced and protected in areas that are exposed to rock strikes”

BMC Kaius ONE 01 (pictured) Weight 7.72kg (58cm) Frameset Carbon Groupset SRAM RED AXS XPLR (44/10-44) Wheels Zipp 303 Firecrest Tyres Pirelli Cinturato Gravel H 40mm Brakes SRAM RED hydraulic disc, 160mm Centreline rotors Finishing kit Kaius 01 Premium carbon D-shaped 15mm offset seatpost, ICS Carbon AERO one-piece full carbon cockpit, Fizik Vento Argo 00 saddle, 2 x BMC aero bottle cages

36cm ● This is the width of the aero-shaped bar across the hoods (the drops measure 42cm) 910g ● It’s a remarkably light frame for a gravel bike (the complete bike is 7.7kg) 10-44 ● A wideranging cassette is paired with a race-ready 44t chainring