Guide: What Kind of Gravel Bike Is the X-LAB GT8? Geometry, Tire Clearance & Who It’s For

Since arriving in the U.S., XDS X-LAB has quickly gained attention for offering an unusually high level of specification and performance at a competitive price. The GT8 has been a particularly strong example, combining a carbon frame, carbon wheels, electronic shifting, and a power meter in a package that has proven difficult to keep in stock at Contender.

What makes the GT8 especially interesting is that the value story is only part of it. With clearance for up to 55 mm tires, wide-range gearing, in-frame storage, and additional mounting points, the GT8 combines features normally associated with both performance gravel bikes and more adventure-focused platforms.

This journal looks at the GT8 itself. Geometry, tire clearance, weight, and comparisons with familiar gravel bikes help define exactly where it fits.

Where Does the X-LAB GT8 Fit in the Gravel Bike Spectrum?

The GT8 sits toward the all-around end of the modern gravel spectrum, balancing the stability and capability of an adventure bike with the speed of a race platform. X-LAB emphasizes stability, control, and long-distance comfort, but describes the frame as retaining "race-ready intent." Carbon wheels, Shimano GRX Di2, and an integrated power meter back that up.

That balance lets the GT8 cover race days, long mixed-surface routes, rougher terrain, and light adventure riding on a single platform.

X-LAB GT8 Geometry & Sizing

The GT8 is offered across six sizes from XS through XXL, with nominal equivalents ranging from 46 to 62 cm. Those size labels are best treated as a starting point rather than a direct translation across brands. Stack, reach, and the complete cockpit dimensions provide a better picture of how each size will actually fit.

The geometry reflects the GT8’s broader approach to gravel. A size medium measures 565 mm of stack and 384 mm of reach, paired with a 71-degree head angle, 435 mm chainstays, a 1,031 mm wheelbase, and 80 mm of bottom bracket drop. Those numbers favor stability and control over quick, aggressive handling as terrain becomes rougher.

X-LAB also makes meaningful changes across the size range rather than scaling the frame around the same components. Crank length progresses from 165 mm on XS and S frames to 172.5 mm on XL and XXL, while stem length ranges from 70 to 100 mm. Handlebar dimensions increase with frame size, and fork offset changes from 55 mm on the two smallest sizes to 50 mm from medium upward.

The result is geometry that supports the GT8's position as an all-around gravel platform. The fit remains performance-oriented, but the 435 mm chainstays, 1,031 mm wheelbase, and 80 mm of bottom bracket drop add stability and composure on rougher terrain.

How Much Tire Clearance Does the X-LAB GT8 Have?

The GT8 has clearance for up to 55 mm tires, which is in the range of a 2.1 to 2.2-inch mountain bike tire. The complete bike comes equipped with 700x45c Continental Terra Trail tires, with both the tires and Branta C45 Gravel wheelset listed as tubeless-ready.

That 55 mm ceiling puts the GT8 in line with the latest generation of high-clearance gravel bikes, where room for 50 mm-plus tires is becoming increasingly common. The current Specialized Crux 5 also clears 55 mm tires, while the SCOTT Addict Gravel reaches 57 mm.

The stock 45 mm tires are a sensible starting point, and the GT8 doesn't need a 55 mm tire to make sense. But the extra clearance leaves room to change the bike's character: narrower, faster-rolling tires suit smoother gravel and mixed road use, while larger-volume tires add grip, comfort, and control as terrain gets rougher. Tire choice doesn't become a limitation as riding evolves.

How Much Does the X-LAB GT8 Weigh?

X-LAB lists the complete GT8 at 19.31 lb / 8.78 kg in a size medium. For a gravel bike with 45 mm tires, carbon wheels, electronic shifting, a power meter, in-frame storage, and mounting points, that puts it in a reasonable place for an all-around performance gravel build rather than an ultralight race platform.

X-LAB also lists the GT8 frameset at 3.92 lb / 1.78 kg in a size medium without the headset. These are manufacturer-listed weights and can vary with frame size, paint, and production specification.

How the GT8 Compares to Familiar Gravel Bikes

The GT8 becomes easier to understand next to the Specialized Crux 5, a current race-focused gravel platform. Both cover similar ground, but they sit at different points on the spectrum.

The latest Crux 5 has moved well beyond the narrow, lightweight gravel formula of the previous generation. Specialized still positions it squarely around gravel racing, but it now combines an 897 gram FACT 10r frame with aerodynamic development and clearance for up to 55 mm tires.

Its geometry is also surprisingly close to the GT8 in terms of fit. Using Bike Insights in the image above, a size 54 Crux 5 measures 560 mm of stack and 388 mm of reach, compared with 565 mm and 384 mm on a medium GT8. The difference is in the wheelbase and rear end: the GT8's 1,031 mm wheelbase and 435 mm chainstays are longer than the Crux 5's 1,026 mm and 425 mm, which makes the GT8 a bit more stable and less race-oriented.

That makes the GT8 a close match to a gravel race bike on fit, with a calmer, more versatile character. Its 55 mm clearance matches the Crux 5, and the in-frame storage and additional mounts give it more range than a dedicated race platform. Carbon wheels, GRX Di2, and a power meter keep it on the performance side of the category.

Who Is the X-LAB GT8 Built For?

The GT8 makes the most sense as a first serious gravel bike or as a substantial step up from a more basic platform. Rather than committing fully to either racing or adventure riding, the GT8 leaves room for a wide range of terrain and riding styles.

The stock 45 mm tires, wide-range gearing with a 40T chainring and 10-51T cassette, in-frame storage, and additional mounting points provide plenty of capability for rough gravel and longer mixed-surface rides. Carbon wheels, electronic shifting, and an integrated power meter keep the build rooted in performance riding, and X-LAB positions the GT8 for everything from gravel racing to adventure rides and short bikepacking trips.

That range is what makes it a strong first serious gravel bike. Rather than picking a lane before you know what kind of riding you'll do most, the GT8 leaves room to find out. Faster tires push it toward racing and smoother gravel, while larger tires, added cargo, and the wide-range drivetrain open the door to rougher terrain and longer days away from pavement, without needing a different bike or a round of upgrades.