BMC Kaius 01 One test: With the Kaius, BMC sets a counterpoint to the traily off-roader Urs. The brand new model is to be understood as an aero road bike with wide tires, optimized for bumpy tracks and bad roads in headwinds. We found out how the bike feels with the super narrow handlebars.
Super light, extremely sleek, uncompromisingly equipped: French rider Pauline Ferrand-Prévot won the first Gravel World Championship on the BMC Kaius One 01. The brand-new gravel bike from the supplier from Grenchen has thus proven its sporting suitability. The gravel racing machine is the exact opposite of the Urs sister model: the Kaius has no mounting options other than the two bottle holders and a top tube bag. In addition, the geometry is largely the same as the lightweight racer Teammachine with a stretched stance and low handlebars, while the Urs is heavily influenced by MTB.
BMC Kaius 01 One: road bike geometry and aero shapes
The BMC Kaius 01 One also has the angular aero tube shapes of the carbon frame from the professional racer, as does the one-piece cockpit - but this is where the Graveller deviates greatly from what you are used to. The handlebars are extremely narrow across all six frame sizes – just 36 cm at the top and 42 cm at the ends of the handlebars (centre to centre). Due to the fact that the lower link is slightly angled, the distance between the humps on the brake levers is only 32 cm.
Extremely narrow handlebar
You have to digest that first, because a rather wide handlebar seems the logical choice, especially off-road, as it offers a larger lever that makes it easier to keep the bike on course. BMC counteracts this with optimal aerodynamics - in a headwind you can of course make yourself nice and narrow with a handlebar width of 36 cm. Does that really work in practice?
Yes, because the Kaius is easy to control and doesn't tend to want to go its own way. The steering angle of 72° from size 52 is only slightly flatter than on the Teammachine racing machine, but the wheelbase is a bit longer. This makes the Kaius as handy as it is smooth-running; in some driving situations you notice that you have to steer with a little more force. If you then switch to the lower link, you have a little better grip on the bike – helpful, for example, at high speeds or on rutted paths where you have to steer against ruts.
An interesting aspect of the frame geometry is the fork length, which is 387mm on the Kaius – 2cm less than on the Urs off-road gravel bike (407mm) and just 12mm more than on the Roadmachine (375mm), which comes with max 33mm tires can be driven. For a gravel bike, the fork of the Kaius is short, which means that the bike doesn't appear as high-legged, and the head tube doesn't have to be that short. Both reinforce the visual proximity to the racing bike. Nonetheless fit according to the manufacturer 44mm wide tires through the frame and fork, which is quite a lot given the intended use. This should allow you to ride anything that seems possible off-road given the seating position and handlebar width. Fortunately, BMC has skipped the option of being able to mount super-wide B650 tires; so the fork and rear end don't have to be extremely wide, as is the case with some competitors. And where the Kaius offroad reaches its limits, the BMC Urs can take over.
Integrated lines: a clean affair
The carbon cockpit with the stem oriented 12,5 degrees downwards is of course an absolute eye-catcher, especially since it is painted in white like the frame and the spacers. This makes the bike look tidy and literally clean, especially since the internal routing of the brake lines also makes cleaning easier. The computer holder, which is screwed on from below, comes with adapters for Garmin and Wahoo; the brake levers are attached conventionally with clamps, so their position can also be changed. As usual, the flat top link is not wrapped with tape, but due to its shape it fits well in the hand.
Super light, well equipped
The sporty, aerodynamic seating position is just one aspect of the Kaius, another is its very low weight: the frame is made with less than 1.000 The weight of the fork is specified at around 400 grams, and the cockpit at approximately 300 grams. The elegant Zipp wheelset is also very light—according to the manufacturer, barely more than 1.350 grams. Its hookless rims with a 25 mm internal width are ideal for wide tires; the freehub offers extremely fast engagement with 66 engagement points.
The rims with the brand-typical "dimples" are 40 mm deep and 30 mm wide; Tires with a width of 35 mm would probably be optimal aerodynamically. Pauline Ferrand-Prévot also relied on tubeless tires with these dimensions - enough for gravel racing.
With pedals, the BMC weighs little more than eight kilos, which has a positive effect on handling and driving dynamics. The bike is also very comfortable, especially at the rear, where the extended carbon seatpost flexes to absorb shocks. The Pirelli 40s, which are already mounted tubeless, roll smoothly and appear to have a good grip overall. Many interesting details can be admired on the frame, such as the special aero bottle holder on the down tube or the smooth "Stealth Dropout" dropout on the right, where the threaded holes for the axle do not go through.
Of course, the equipment with SRAM Red AXS XPLR in the 1×12 version with a 42 chainring and 10-44 cassette is also fantastic. The wide gradation up to gear reduction for the steepest climbs comes at the expense of fine gear steps, and those who want to use the Kaius as an all-rounder given its similarity to road racing bikes might be better served with 2×12 gears. But this is where an interesting property of the SRAM AXS comes into play: It can be converted with manageable technical effort; you only need a SRAM Red double chainring (approx. 300 euros) and the electronic front derailleur (approx. 460 euros), and of course a narrower geared cassette (SRAM Force 200 euros).
The already considerable price of the Kaius 01 One would of course increase even further as a result; i.eHowever, the sum of all parts explains why the top model has to be so expensive. With SRAM Rival AXS 2×12, conventional handlebars and in-house carbon wheels, the bike is of course also available for less than half. Then you can't enjoy the "fresh" paintwork in white-green, but you get wider handlebars and a double chain ring in the interesting "Wide" gradation 43/30. So equipped, the Kaius is an ideal all-road bike that combines road racers and gravel bikes and is almost closer to the Teammachine than the Urs. If you approach the topic of gravel bikes from a racing bike, you should like this concept.
