BMC Kaius 01: 52mm clearance, sub-kilo frame, and a Halo fork borrowed from the road

BMC has replaced its 2022 Kaius with an entirely new platform that grows tyre clearance to 52mm, trims 63g from a frameset that now weighs a claimed 998g in size 54, and achieves what the brand calls a 12% improvement in aerodynamic efficiency as a complete system compared to the outgoing model. The bike is called the Kaius 01, it costs from $6,199 to $12,999 across three builds, and it arrives timed for Traka with a complete overhaul of the frame, fork, cockpit, and geometry.

The original Kaius debuted in late 2022 as a road-inspired aero machine that proved its race credentials immediately when Pauline Ferrand-Prévot won the inaugural UCI Gravel World Championship on one. That bike ran a maximum 44mm to 45mm of tyre clearance, used road-like geometry, and drew its aero philosophy from the Teammachine SLR 01. It was fast on smooth gravel and fast tarmac, but the narrow cockpit, aggressive reach, and limited rubber became friction points as gravel racing evolved toward bigger tyres and rougher courses. BMC's head of R&D, Stefan Christ, has said the original Kaius received strong feedback while gravel racing was still emerging, but that retaining its feel while tailoring it to today's courses was the core challenge for this generation.RouleurCyclistGRAN FONDO

The headline number on the new bike is 52mm of tyre clearance with the ISO-mandated 6mm of space on each side maintained throughout. BMC optimised the frame around 45mm tyres but the added room runs up to 52mm — an 8mm increase over the outgoing maximum. To make it fit, chainstays grew 5mm to 425mm. The complete frameset weighs a claimed 1,469g: 998g frame, 400g Halo fork, and 134g AS10 aero seatpost. That last number is notable because aerodynamic tube shapes, a wider fork, and a larger tyre envelope normally push weight up, but BMC says its revised carbon layup approach — the same thinking applied to the Teammachine SLR redesign that saved 220g on that platform — allowed a 4% weight reduction on the Kaius frame despite the added demands.VeloBikeRumorCycling Weekly

The aero story centres on the Halo fork, which pushes its legs outward to channel airflow away from the tyre and past the rider's legs — the same principle behind the Teammachine R fork developed with Red Bull Advanced Technologies. BMC claims that as a standalone frameset, the new Kaius is only about 1% faster than the previous generation; the bigger gain comes at the system level, where rider, bike, and kit together produce a claimed 12% drag reduction at 40 km/h with 45mm tyres. The cockpit is the new ICS Carbon Aero Gen 2, which routes cables under the bar rather than through it for easier maintenance, and it comes in a narrower width than the outgoing unit to comply with UCI regulations. The frame also adopts the Arete seat tube, thinned in the centre for engineered vertical compliance, working in concert with the AS10 seatpost borrowed from the Teammachine SLR.VeloRouleurEscape Collective

Geometry changes are substantive. Stack increases 11mm across all six sizes (47, 51, 54, 56, 58, 61cm), reach shortens 5mm, and fork trail extends from 68mm to 72mm — a 4mm swing toward more stable, predictable front-end behaviour on loose or technical ground. Bottom bracket drop stays constant at 79mm, but because the tyres are bigger, ground clearance effectively increases 10mm. Chainstay length rises from 420mm to 425mm. Head tube angle is approximately 71° depending on frame size and is essentially unchanged from the original, but smaller sizes get a 5mm longer fork rake to keep the overall trail consistent. The combined effect, according to riders who tested the bike in Sardinia ahead of launch, is a front end that inspires more confidence on fast descents without sacrificing the upright efficiency that makes the Kaius feel quick over long flats.Cycling WeeklyBikeRumorBikeRadar Gravel

The Kaius 01 comes in three complete builds and a frameset. The top-tier One uses SRAM Red XPLR AXS and is priced at $12,999 / €10,999 / £9,999, and hits 7.1 kg in a size 54 with Continental Dubnital 700x50c tyres. The Two steps down to SRAM Force XPLR AXS at $8,999 / €7,999 / £7,299, while the Three uses SRAM Rival XPLR AXS at $6,199 / €5,499 / £4,999. A frameset (listed as VAR0, available ready to paint) sells for $5,099 / €4,499 / £3,999. Each build is 1x and electronic-only; there is no front derailleur mount, no mechanical shifting option, and no 2x compatibility. The frame accepts chainrings from 32t to 50t, and an integrated chain guide covers 38t–50t. Bottom bracket is a threaded T47 x 85.5, a notable choice given the tyre clearance demands. Cargo provisions include a Cargo Plate under the top tube, rivets above and below the top tube for bag mounts, AeroCore bottle cages integrated into the down tube, and a third cage mount under the down tube — but there is no in-frame storage.GRAN FONDOBikeRumorCyclist

The Kaius 01 arrives into a gravel-race segment that has converged quickly on 50mm-class clearance, deeper aero shaping, and external cargo systems — territory where the Cervelo Aspero 5, 3T Exploro RaceMax, and Specialized Crux all compete. Where the first Kaius was conspicuously narrow and road-adjacent, this one fits more naturally alongside those rivals. What keeps it distinct is the explicit Teammachine R lineage — the Halo fork, the AS10 seatpost, the AeroCore cages — along with the 1x-only, electronic-only constraint that BMC frames as a performance decision and that Velo's Josh Ross notes is 'hyper-focused.' Riders who want a mechanical shifting option or a budget 2x build will need to look elsewhere; those who want the lightest possible SRAM XPLR setup in a legitimate race geometry now have a Swiss option that has already won at gravel's highest level.VeloBikeRadar GravelRouleur