The Trek X-Caliber 8 is a sure-footed 29er hardtail mountain bike, with plenty of reliable elements that boost its score to impressive levels, but a few missteps that hold it back from quite making it as one of the best hardtail mountain bikes we’ve tested. There’s a whole lot to like though.

Twenty nine inch wheels have long been an integral part of Trek’s mountain bikes, especially the hardtails. And where initially there was uncertainty and hesitation in the industry, Trek pushed on with this larger wheel size and the persistence paid off: with 29in wheels now accepted globally and across all mountain bike categories, not just for the cross country crowd.

Trek’s early 29in wheel bikes were XC hardtails and since then, the X-Caliber has shifted upmarket and now sit between the entry-level Marlin and the carbon Pro-Caliber. All three platforms run 100mm travel forks.

We’ve pulled in the X-Caliber 8 for this review, which is just shy of the Scott Scale 965 in price and shares many of the same components. With all four bikes on test running Shimano brakes and 1×12 transmissions, we were keen to take this consistency a step further and chose models with regular seatposts, rather than droppers. Primarily for comparing the weight of the bikes, but riding dynamics and overall value played a part too as we felt it really levelled the playing field, and maintained the XC hardtail design ethos.

With a steeply sloping top tube and a super-low standover height the X-Caliber is a very striking bike. It’s a silhouette that’s mirrored through all the brand’s hardtails – with the notable exception of the carbon Pro-Caliber – as is the wide size range that Trek is well known for offering. Seven frame sizes are available (with the XS and S rolling on 27.5in wheels to keep proportions in check) with a useful M/L option that’s a great problem solver for riders stuck between the popular M and L options. So hats off to Trek for this level of commitment to getting a good fitting bike.

When it comes to new frame standards, Trek has always been an early adopter, so it’s no surprise to see a tapered head tube and Boost hub spacing on the X-Caliber frame. But it’s Boost with a twist… here, Trek using 141mm rear dropout spacing with a traditional Q/R hub, rather than a 148mm bolt-thru design.

It’s not a deal breaker though, as the fixed rear triangle of a hardtail doesn’t need stiffening up like a full suspension design, and a quick online search reveals plenty of wheel upgrade options from the likes of Hunt, Hope and Bontrager for the 141 standard.

A modern touch that hasn’t been executed as well as on other bikes in test, is the internal frame routing for the cable and rear brake hose – they’re not clamped where they enter the down tube and rattle noisily on rough terrain, just like on the Trek Roscoe in our Hardtail of the Year test.

Suspension

Trek has equipped the X-Caliber 8 with a RockShox fork and it’s listed as a Judy SL, so we expected to see an upgrade or two. However, all the tech is identical to the regular Judy forks seen on the Cube and Scott – a tapered aluminium steerer, steel upper legs, a Solo Air spring and the brand’s basic TurnKey damper.

The Trek is the only bike in test that doesn’t have a remote lockout lever though, just a simple dial on the top of the fork leg, with an on/off function and no graded adjustment between those points. At least it’s one less cable to maintain and gives more handlebar space for a dropper post remote lever.

And while the X-Caliber frame does not use a bolt-thru rear axle, the 100mm travel Judy fork does have the 15x110mm Boost hub standard – although the website lists the lighter tooled axle as standard, our test bike had the same QR lever operated version as the Scott Scale.

Components

Shimano was slow to filter its 1×12 transmissions down to the lower price points, but it’s there now and proving to be a very popular choice, all four bikes in this test using Shimano drivetrains. The X-Caliber’s specification lists a Shimano chainset, but our bike shipped with a model from FSA, and it’s the only deviation from a complete Shimano drivetrain.

Trek has also gone with a smaller 30t chainring and combined with the Deore 10-51t cassette you get a super-low gear, which is useful on the climbs because at 13.53kg (29.82lb) the Trek is the heaviest bike in test.

Another wise move is the genuine Shimano chain which performs faultlessly in wet filthy conditions and plays well with the steel FSA chainring. The benchmark XT rear mech is good to see, as is the rubber chainstay protector, which is a detail the other three brands seemed to have overlooked.

Performance

The dropped top tube, wider 750mm bar, long wheelbase and slackish 68º head angle (the slackest of the four bikes) give the X-Caliber the look and feel of a trail bike. However, the Trek’s geometry and attitude is not in the same league as the most progressive 100mm trail hardtails such as Kona’s test-winning Mahuna.

Even on this size XL, the frame’s front triangle is very compact, especially when compared to the Giant XTC, but it still sports two sets of bottle cage mounts – essential on an XC bike. In fact, Trek has added plenty of mounts to the X-Caliber, with fittings for a rack and kickstand making it a very capable all-terrain bike.

With one of the lightest wheelsets on test, we expected some zip and liveliness from the X-Caliber but it lacked the immediate urgency of the Scott and Giant and on longer non-stop cross country blasts, its weight was noticeable, certainly towards the end of the ride.

You can’t knock the Trek’s sure-footed nature though – the lengthy wheelbase (for an XC hardtail) and wide bar aid stability, and it was only the Judy fork’s lack of refinement that held us back from diving into more challenging terrain. A slightly shorter stem would no doubt help here too.

Although the compact front end still has a tall 525mm seat tube, the seat stays are dropped, giving a tighter rear triangle. This certainly gives the X-Caliber a chuckable hardtail vibe, but the ride quality was a touch less compliant than the other bikes here.

With that in mind, there’s plenty of frame and fork clearance for higher volume tyres to help smooth the ride further, and Trek helpfully supplies the X-Caliber 8 with rim strips, valves and sealant so you can go tubeless straight from the box and reap the benefits immediately.

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