The XDS RT9 is the lightest production road bike and a discounted engineering marvel. The commercially available model simply requires a few upgrades.

• The frame weighs 550 grams and the fork 300 grams.
• The weight of the bike ready to ride, without pedals, is 6.1 kg.
• Threaded BSA bottom bracket
• Standard round seatpost with external clamp
• Maximum tire clearance: 32 mm
• Expect a price reduction of about 4,000 $ compared to the S-Works Aethos 2
• The RT9 is not focused on aerodynamic performance, but «sleek tube junctions and a reduced frontal area inherently contribute to lower aerodynamic drag»
• The final model will include a power meter as well as 50 mm aerodynamic-optimized wheels, while meeting the weight targets
• XDS is one of the largest bicycle manufacturers in the world and X-Lab is a sub-brand of XDS specializing in higher-performance options 

Depending on your interest in professional cycling, you may have already seen this bike. Even by following it closely, you may have missed it.

XDS is the title sponsor of the XDS-Astana team, but the bikes you see do not show it. Instead, you spot a large X-Lab logo. Furthermore, the framework that generated the most interest is the X-Lab AD9, an aerodynamic bicycle.

Allow me then to begin by introducing you to the XDS (Xidesheng) X-Lab RT9. XDS is the parent company and, although few people know the name, XDS describes itself as «one of the largest carbon fiber manufacturers in the world and the largest bicycle manufacturing plant in China.». The second part of this name designates the performance branch of XDS.

I prefer to avoid comparing too much with other brands, but we can draw a parallel with Specialized and S-Works. XDS offers a wide range of bikes for all types of cyclists, but the high-end bikes usually feature the X-Lab logo. Finally, here is the model RT9.

The XDS RT9 is the lightest production road bike on the market, with a weight of just 550 grams in size M. As with other attempts to win this title, the RT9 relies above all on lightness, effectively neglecting aerodynamics as a design criterion. Despite this similarity, XDS delivered a slightly different narrative from Specialized and Scott regarding their respective bikes in the race for lightness. Echoing Specialized's remarks, XDS stated that «the design philosophy prioritizes structural efficiency through a simplified tube geometry» and that «the use of round-section tubes minimizes stress concentrations, thereby allowing for a significantly thinner carbon layup and an overall reduction in material consumption.».

The brand collaborated with Toray Industries to achieve this feat, and the RT9 frame uses a blend of T1100 carbon fibers, «supplemented by M40X fibers and a small proportion of pitch-based carbon to improve stiffness and vibration damping.». These materials offer an optimal balance between strength and weight, with the T1100 currently being the best carbon (just another product, subject to progress and new models) that Toray makes available to most manufacturers. Then there is the M40X, similar to the T1100, but lighter and stronger.

But such sophisticated carbon technology and such advanced manufacturing are not measured by driving comfort. The bike is light, to be sure, but what about the handling on the bike?

Whatever the final model marketed, this is not the final configuration. The price has not yet been announced, and XDS states that the suggested retail price would be less than 10,000 $ and that this model would include a power sensor. The groupset I tested is the latest SRAM RED AXS and the frame is compatible with the SRAM UDH standard. For the cockpit, I mainly use XDS components with a Selle Italia saddle featuring carbon rails. However, the seatpost is not brand-specific; The RT9 is equipped with an XDS model with a side-clamp seatpost fastening. The handlebar and stem form a one-piece unit with internal cable routing in front of the steerer tube. The handlebar is round and I use a 37x100 mm, because widths of 37/38 or 39/40 cm do not exist with a 110 mm stem. The design allows the steerer tube to extend above the stem, which is always practical for finding adjustments early on.

 The wheels used are the XDS Branta C50 ULR. As the name suggests, it is a 50 mm deep aerodynamic wheel with carbon spokes. The internal width is 21 mm and the external width is 28 mm. The stated weight is 1,250 grams and the tires on my test bike are…