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Giant Fathom Range Review

Giant Fathom Review


£1,099.00 - £1,299.00

Finance from:

£61.06/month (0% APR)

High-quality aluminium alloy frame
120mm travel fork on the 27.5” bikes, 100mm on the 29ers
27.5” and 29” wheel options
SRAM Eagle 1x12 speed drivetrains
Hydraulic disc brakes
Dropper Seat Post on every bike


Trail hardtail


12.4Kg (27.3Kg)*

Designed for the sort of trails that mountain bikers love to ride most

Updated: 17th October 2019


The Giant Fathom we review here is a hardtail mountain bike that comes in two different flavours. The Fathom 29 is a modern cross-country bike that combines fast-rolling 29” wheels with dialled XC geometry which makes it fast uphill and capable on the descents. The Fathom 27.5” rolls on smaller wheels but has slacker angles and more suspension travel which make it more confident on technical descents.

With short stems, wide handlebars, tubeless tyres and dropper posts both these bikes are ready for some serious trail fun straight out of the box. Prices around the £1,000 mark make the Fathom an affordable alternative to a full suss MTB.

*Fathom 2 - Size M tested, no pedals

Giant Fathom frame


High-Quality aluminium alloy

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.

Unlike most other bike brands, Giant make all their frames in-house, so you can be sure of the best quality and value.

Giant Fathom Suspension


120 or 100mm of travel

I felt like I could happily ride this bike all day long over pretty much any terrain and without major issues. Bike Radar

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.

Giant Fathom groupset


Wide bars, short stems and dropper posts

The trail ready component spec on the Fathom is perfect for fast paced fun on challenging tracks.

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.

Giant Fathom wheels


27.5” or 29er

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.

Tubeless ready out of the box, the wheels are a plus point for the Fathom

Giant Fathom

Best for

MTB trail riding

Designed for the sort of trails that mountain bikers love to ride most, the Fathom 27.5”, with its wide tyres and 120mm travel fork, is a great alternative to a full-suspension bike. Ideal for trail centre loops, these bikes offer a confident ride on technical descents and are lightweight enough for efficient climbing. If you enjoy the descents more than the climbs and want to get the most fun out of every trail section without breaking the bank, then the Giant Fathom 27.5 is an ideal choice.

The Fathom 29 has more of an XC focus with its fast-rolling tyres and 100mm travel fork balancing climbing speed with descending ability. These bikes are best on flowing singletrack, but the big wheels do help them roll smoothly over rougher terrain. The Fathom 29 isn’t a pone trick pony and is versatile enough for trail centre loops as well as long-distance cross-country adventures.

Giant Fathom frame detail Giant Fathom disc brakes
Giant Fathom brake lever Giant Fathom dropper post
Giant Fathom fork crown lockout lever Giant Fathom fork crown

Giant Fathom range models

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