Giant Fathom Review

Both the 27.5” and 29” wheeled bikes are made from the same ALUXX SL-Grade aluminium alloy. Offering best-in-class strength to weight ratios this is the highest grade of alloy that Giant use for their MTBs. The tubes are formed and butted to keep things lightweight and deliver a high-performance ride quality. Internal cable routing keeps the lines nice and clean, while the low standover height is great for those challenging sections.

The geometry is slightly different for the two-wheel sizes which gives these two bikes their slightly different flavours. The 27.5” wheeled bikes have a slack 67° head-tube angle which gives the bike more of a ‘trail’ feel. The 29ers have a slightly steeper 69° head angle which offers a more cross-country feel. Both bikes have a long top tube for a confident riding position while the short chainstays keep things nimble in the tight. Both the Fathom 1 and 2 share the same high-quality frame.

With a 120mm travel fork, the 27.5” wheeled Fathom bikes are aimed squarely at technical trail riding. The 29er models have more of a cross-country focus with a 100mm travel fork. That said, you can ride both bikes confidently at trail centres. Other than the amount of travel offered the suspension forks are the same on both the Fathom 29 and 27.5 models.

The suspension forks on all the bikes are air-sprung. This means that they are easy to adjust for different rider weights. The rebound damping dial allows you to set the fork up for composed performance on the trail. You can stiffen the fork up for climbing the open it up again for the descents with the easy to reach compression damping dial. The Fathom 1 has a RockShox Recon fork which offers plusher performance.

The 12-speed SRAM Eagle drivetrains are a real highlight of the new Fathom bikes. With its big rear cassette, SRAM Eagle gives you a very wide range of gears while keeping the simplicity of a one-by drivetrain. The clutch rear mech and narrow/wide chainring keeps the chain in place even over the very roughest terrain. Hydraulic disc brakes give you powerful all-weather speed control.

Giant has put a lot of thought into the components on the Fathom. It is great to see wide 780mm handlebars and short stems on every bike as this gives you more control when riding challenging terrain. A dropper post is fitted as standard which means you can make the most out of every trail section without having to stop and fiddle with your seat clamp.

Like the frames, the wheels on the Fathom are made in Giant’s own factory, so you can be sure that you are getting a top-notch wheelset for the price point. The wheels and tyres on every model are tubeless-ready, so you don’t need to convert them to make the most of this puncture reducing technology.

As with the suspension and frame geometry, the wheels have different flavours to match the different sizes. The 27.5” wheeled fathoms roll on Giant’s AM wheels with 30mm trail-oriented rims. The high-volume 2.6” Maxxis Ardent tyres offer plenty of float for a smoother ride over rough terrain. The Ardent is a fast-rolling tyre that is ideal for hard-pack riding but does lack grip on looser surfaces. Hard-charging riders will probably want to upgrade to a more aggressive tyre like a High Roller, especially at the front. The 29ers have lighter weight XCT wheels with narrower rims matched to 2.35” Maxxis Rekon/Forekaster tyres. This fast combination is ideal for cross-country riding.