The XDS X-LAB RT9 is an ultralight climbing bike that pushes the boundaries of weight, with a claimed 550g frame and complete builds around 6.2kg. It offers exceptional value compared to Western brands, with a Dura-Ace Di2 build under $10,000. However, the stock Branta C50 wheels and Maxxis/Michelin tires are widely criticized for being too deep and stiff, making the ride twitchy in crosswinds and rough on descents. Availability outside China remains unclear, and the frame weight is often measured higher than claimed.
Pros
- Exceptionally lightweight frame and complete build, among the lightest production road bikes12
- Very stiff frame and efficient power transfer, especially during climbs13
- Excellent value: complete Dura-Ace Di2 build under $10,000, significantly cheaper than Western competitors214
- Comfortable over long distances despite stiffness; suitable for ultra-endurance events1
- Advanced carbon technology: T1100, M40X, pitch-based carbon, thin walls (as thin as 0.4mm)1
- Standard threaded bottom bracket (BSA) and round seatpost simplify maintenance and compatibility51
- Integrated dual-sided power meter with Apple Find My anti-theft technology in the crankset1
- Lifetime frame and wheel warranty, plus free post-purchase cockpit swap through dealers1
Cons
- Stock 50mm deep wheels are too deep for a climbing bike, causing twitchy handling and instability in crosswinds14
- Stock tires (Maxxis High Road or Michelin Pro 5) are underwhelming and compromise ride feel1
- Actual frame weight is 600-605g, higher than the claimed 550g24
- Limited availability outside China; unclear international distribution and difficult to purchase in the US/Europe143
- Integrated one-piece cockpit limits sizing options and is not easily swappable; no 90mm stem option1
- Rider weight limit of 220 lbs (100 kg) restricts larger cyclists1
- Tire clearance limited to 30mm (32mm max on some models), limiting tire choice1
- Stock build uses house-brand wheels and power meter/crank, with no customization for bar/stem or crank lengths; power meter tested about 10 watts off4
Key Facts
- Claimed frame weight 550g; measured 600-605g by third parties24
- Complete bike weight: 6.2kg (size L) as tested, 5.9kg (size S) ready to ride minus pedals21
- Frame material: Toray T1100 and M40X carbon fibers, with pitch-based carbon for vibration damping1
- Wheelset: Branta C50 ULR, 50mm deep, carbon spokes, ceramic bearings, 1,230g claimed, 1,228g measured21
- Bottom bracket: BSA threaded, 29mm spindle21
- Tire clearance: maximum 30mm (32mm on some models)1
- Price: $9,150 as tested with Dura-Ace Di2; frameset $3,4991
- Rider weight limit: 220 lbs (100 kg)1
Reviews & Ratings
15:32The reviewer examines the XDS X-LAB RT9 frameset, which is claimed to be the lightest in the world. The actual frame weight is 600-605g, slightly heavier than the claimed 550g, but comparable to the Athos frame. The reviewer notes that the RT9 offers excellent value, with a complete Dura-Ace build priced under $10,000, and includes features like a steering wheel exchange program and modern geometry. The build weighs 6.2kg as claimed.
08:27The reviewer provides a first look at the XDS X-LAB RT9, the climbing bike that the XDS Astana team will use in the 2025 World Tour. He describes it as a classic climbing bike with cylindrical tubing, a threaded bottom bracket, and a classic seat collar. The bike weighs 6.9 kg, and mechanics are confident they can bring it down to the 6.8 kg weight limit. It shares a similar paint job with the aero model, featuring black on the down tube and forks, white X-LAB lettering, and Astana team colors on the top tube. The reviewer notes that riders will have a choice of Vision handlebars, and the bike is equipped with Shimano groupset, Prologo saddle and tape, and Vision wheels with Continental tires. He finds it 'pretty banging' and appreciates its classical design.
08:34The reviewer presents the XDS X-LAB RT9 as a high-end Chinese road bike, ridden by the Astana Kazakhstan team in mountain stages. He details a lightweight custom build by his friend Cheny Noir, weighing 6.7 kg with pedals, mounts, and bottle cages. The reviewer test rides it on a 3 km loop and finds it fast, stiff, and responsive, suitable for hilly or mountainous terrain. He notes that high-end Chinese bikes offer excellent value and that brand premiums are often unjustified.
16:12The reviewer tests the XDS X-Lab RT9, an ultralight road bike, during an Everesting challenge. He praises its climbing ability, stiffness, and value but criticizes the stock Branta C50 wheels for being too deep, stiff, and nervous, especially in crosswinds. He replaces the tires and wheels, noting significant improvements. He considers it ideal for climbers and those seeking efficiency, but notes limitations like tire clearance and rider weight limit.
10:51The reviewer discusses the XDS X-LAB RT9, a lightweight climbing bike from XDS, highlighting its advanced carbon fiber technology, ride quality, and component choices. They note its impressive low weight and stiffness but criticize the integrated handlebar sizing and stiffness, as well as the stock tires. The bike is not yet available in the US, and final build specs and pricing are uncertain.
The reviewer describes the XDS X-LAB RT9 as the world's lightest production road bike, featuring a 550-gram frame and a complete build weight of 6.1kg. It is praised for its exceptional lightness, balanced stiffness, and significantly lower price compared to competitors like the S-Works Aethos 2, though it has drawbacks such as an overly stiff handlebar, limited integrated cockpit sizes, and difficult purchasing options.
The reviewer describes the XDS X-LAB RT9 as an exceptionally lightweight climbing bike with a very stiff frame and excellent power transfer, but criticizes the stock Branta C50 wheels for making descents twitchy and crosswinds unstable. The bike offers strong value and comfort over long distances, though the wheels and stock tires are considered drawbacks.
The XDS X-LAB RT9 (also referred to as AD9) is a lightweight carbon road bike discussed by forum users. It's compared to the Specialized Aethos, with users noting its competitive weight (around 6.1kg in a ready-to-ride setup with 50mm aero wheels) and potential as a more affordable alternative. Key attributes mentioned include its use of high-modulus carbon fiber to achieve low weight, IS52 headset standard for compatibility, and mixed signals about international availability. Users debate whether it's a direct Aethos competitor or knockoff, with some noting limited production and high costs. Recently, XDS launched the RT9 in the US at Sea Otter, building a dealer network and selling directly for around $9K with free shipping. However, the stock build has been criticized for using house-brand wheels and power meter/crank (the power meter tested about 10 watts off but consistent), heavy 50mm wheels on an ultralight climber, no customization for bar/stem or crank lengths, and an expensive SLR Boost saddle. Some users find the pricing uncompetitive compared to Western brands with Shimano/SRAM cranks and branded wheels. XDS is reportedly working on a 5kg build, and users suggest easy weight savings like 900g shallow carbon spoke wheels, lighter tires, and a carbon fiber saddle with no padding.
AI Summary
Pros
- Competitive lightweight performance similar to high-end bikes like Specialized Aethos
- Potential price advantage over comparable lightweight bikes
- Uses standard IS52 headset for easy component compatibility
more pros in the review
Cons
- Limited availability and unclear international distribution strategy
- Proprietary handlebar/spacer system that may limit customization
- Reportedly high production costs leading to limited production
more cons in the review
Key Points
- Weight around 6.1kg in ready-to-ride setup
- Uses high-modulus carbon fiber construction
- IS52 headset standard
more key points in the review
Specifications
Attributes
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