BMC Kaius 01 One review: this Kaius is the gravel racer it should always have been – but there's a cheaper bike I'd buy

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The original Kaius was a groundbreaking take on racy gravel bikes – aero optimised, very light and very fast in the right conditions. However, it had issues – namely limited (44mm) tyre clearance; a very narrow bar; steep, low and long geometry; plus a huge price tag. 

The 2026 Kaius improves on all of these.  

Tyre clearance is up to 52mm – not industry-leading by any imagination, but improved – and it’s less expensive mainly thanks to BMC developing its own wheelsets rather than using aftermarket brands with set pricing.

Game-changing geometry

The key improvements you need to know about are in the geometry. Cleverly, BMC hasn't just slackened the Kaius out and made a lightweight version of the very capable URS LT.

Instead, the head angle has been steepened slightly to 71 degrees, but at the same time the fork trail has been increased to 72mm (up from the road-bike 68mm of the previous iteration).  

This effectively shifts the front axle forwards, compensating (and then some) for the head angle, and brings about far more stable handling than its predecessor. 

The front end gets a bit more stack and BMC has shortened the reach, which contributes to a more reasonable fit for more riders, while the longer wheelbase and chainstays, and increased bottom bracket height, help accommodate larger tyres. 

This Kaius is now 1x only, rather than the compromises of the previous bike’s design. That means, with the reshaped bottom-bracket shell and front-derailleur provision removed, it can now accommodate up to a 50-tooth chainring with a better chainline. That should be sufficient to meet the needs of the strongest gravel racers. 

All of these subtle changes amount to a bike that’s just as fast on the road and on smoother gravel roads as the previous version, but it’s so much more capable when the going gets rougher. 

Out has gone the super-narrow 360mm bar width of the old bike, in favour of a more moderate 390mm at the hoods with a flare to 440mm in the drops.  

It’s a small 30mm shift in width, but the effect when traversing technical woodland singletrack is transformative. Where the old bike was a handful, nervous and stuttering, this Kaius enables you to flow through turns and drops with confidence. That said, it still feels stiff on choppier surfaces. 

I’ve even taken the Kaius to my local skate park for a cruise around the bowls and banks, something I never would have done on the previous bike. 

Lighter and more aero

BMC has managed to take 63g out of the frame weight, which isn’t a lot, but considering the improvements in tyre clearance and changes in the physical dimensions of the tubes, it’s still worth noting. 

The aero package includes BMC’s AeroCore bottle cages that integrate smoothly into the frame, albeit the BMC lacks down tube storage beneath them. Instead, BMC has taken the same approach as Giant’s Revolt Advanced SL, in looking to reduce weight, knowing that riders can add a frame or top-tube bag with the provided mounts in place on the frame. 

The ride quality is a step up from the previous bike, with the new wider cockpit enjoying the added benefit of having a bit more compliance, helped by the increased tyre volume. Despite that, compared to its closest rival in 2026’s Bike of the Year, the Giant Revolt Advanced SL 0, the Kaius is a firmer ride, especially at the rear.  

The firmer ride is a trade-off that comes with the stiffness through the bottom bracket and the sharpness in the steering. On smoother gravel roads and hard-packed byways, the BMC has ample forgiveness in its ride, but on choppy root-and-rock-strewn singletrack, it can kick somewhat.  

I’d like to take advantage of the Kaius’ increased tyre clearance and move up to a 50mm gravel tyre, such as the Schwalbe G-One RS PRO TLR, as fitted on the Argon 18 Anti Matter. 

Cheaper… well, not as expensive

The Kaius 01 One is an expensive bike (£9,999 / $12,999 / €10,999), but it’s less expensive than the previous iteration (£11,350 / $11,999/ €11,499), despite sharing many of the same specifications between bikes, including the same premium carbon in the frame and fork, and a new development of the ICS aero cockpit.

The new bike gains a power meter in its full Red XPLR groupset and there are no downgrades (the old bike used a Force cassette rather than Red). 

The major change is to the wheels. BMC now offers its own design – the CG 39 SL Carbon, with a 39mm-deep, 25mm internal rim laced with carbon spokes to hubs with DT Swiss internals. 

At a claimed 1,380g a pair, this is a light offering, set up here with Continental’s gravel-racing ready Terra Competition Race Rapid tyres in 45mm. This combo absolutely shines on tarmac and gravel roads.  

The V-shaped tread pattern, Continental says, is designed to reduce drag. Effectively, it’s an aero-gravel tyre (Cadex has done a similar thing with the GXR tyres on the Revolt Advanced SL).  

My whole test period took place during the UK’s heatwave summer, so I can’t judge the tyres on their all-weather performance.

On loose and dusty off-road corners, the grip is ample, although the front has a tendency to shift under load. That's something I haven’t found on tyres with a little more pronounced tread on their shoulders, like the similar 45mm width on the Revolt Advanced SL 0, or the much larger tyres of the Argon 18 and Ridley Kanzo Fast. 

On harder surfaces and tarmac, however, these are blisteringly fast, with the 45mm width and rounded profile making them feel more akin to an oversized road tyre than a sluggish off-road tyre out of place on the wrong surface. 

Price-wise, BMC is competitive, something it has struggled with in the past. Compared to some big-name rivals, Specialized’s S-Works Crux 5 with Red AXS XPLR is more expensive at £11,999 / $14,000. Giant’s range-topping Revolt Advanced SL 0 is the same price in the UK at £9,999, and $999 cheaper in the US at $12,000. 

Trek’s Checkmate SLR 9 AXS is cheaper at £8,950 / $11,999. 

Cannondale’s similarly lightweight SuperX Lab71 is more expensive in the UK at £10,800, but $500 cheaper in the US at $12,499. 

BMC Kaius 01 One bottom line

The new Kaius 01 One largely rights the wrongs of the original Kaius. It’s far better off-road, has ample tyre clearances, better handling and is less expensive. 

The specification for this premium edition is as good as it gets, and although I think it would benefit from a larger tyre to reduce a bit of chatter on rough terrain, for most rides and races, the super-fast Continental tyres will impress in dry conditions.  

For mixed-surface rides, the Kaius is a brilliant option. As good as it, however, there are more rounded options available.

Personally, I’d look to a cheaper model such as the Force XPLR-equipped Kaius 01 Two at £7,299 / $8,999 / €7,999. It shares everything bar the groupset for a not insignificant £2,700 saving. 

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