NOX HeLIUM 5.9 All-Mountain in Review

With the HeLIUM, NOX have developed a new universal frame platform around the FAZUA motor. We’ve already been impressed with another version of the bike. How does the 27.5” NOX HeLIUM 5.9 All-Mountain fare against the competition?

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**NOX** HeLIUM 5.9 All Mountain Expert | FAZUA EVATION/252 Wh | 150/150 mm (f/r)
19.52 kg in size L | € 5,999 | manfacturer’s website

The NOX HeLIUM is a very versatile bike. It’s available in two versions: the ENDURO, which has a whopping 180 mm of travel, and the All-Mountain, which offers 150 mm of suspension travel. We tested the latter in this test. If that wasn’t good enough, you can also choose between 29″ or 27.5″ wheels and two spec options. The NOX HeLIUM 5.9 All Mountain Expert in our test is the entry-level model and retails at € 5,999. This version rolls out of the factory on smaller 27.5” wheels and hits the scales at 19.52 kg. All models share the same carbon frame, alloy rear-end and FAZUA Evation drive integrated in the down tube. In contrast to the smooth main triangle, the rear end with its welded seams and machined parts looks rather rudimentary. In typical FAZUA style, the speed sensor is attached to the chainstay, though compared to the Lapierre, the sensor of the NOX is even more exposed and thus more likely to get damaged. The routing of the sensor cable from the chainstay to the bottom bracket shell could be neater.

NOX HeLIUM 5.9 All-Mountain Expert specs and weight

While the frame could do with a little more love for detail, the spec of the NOX is spot on. The SRAM GX Eagle drivetrain provides shifting that is in no way inferior to the more expensive models. With a whopping 170 mm drop and its quick, smooth operation, the RockShox Reverb dropper delivers unrivalled performance. Thanks to 200 mm rotors front and rear (free upgrade from 180 mm rotor at the back) the Magura MT5 brakes are powerful and stable enough to handle long descents without fading. Smart details such as high-quality ODI grips make the other two bikes look a little cheap, at least in terms of contact points. Like the rear shock, the RockShox Pike Select fork offers 150 mm of travel. While there’s actually nothing wrong with the Super Deluxe shock, the current tune doesn’t harmonise well with the Helium’s kinematics.

**Harsh**
The shock tuning of the HeLIUM is not right. The suspension doesn’t work sensitively, feels harsh in the first part of the stroke and blows through its travel way too fast, especially with bigger impacts and hard landings.

**Your choice!**
Thanks to the adjustable dropouts, the NOX HeLIUM can take either 27.5 ”or 29” wheels. After testing the bike with both setups, we definitely recommend the 29er version.

**Constant improvements**
In the lowest gear, the chain is dangerously close to the main bearing. The glued chainstay protector shows signs of wear after the first few meters. You’ll have to stick on new tape again and again.

NOX HeLIUM 5.9 All Mountain Expert

€ 5,999

Specifications

Motor FAZUA EVATION 55 Nm
Battery FAZUA Battery 250 252 Wh
Display FAZUA Remote B
Fork RockShox Pike Select R 150 mm
Rear Shock RockShox Super Deluxe R 150 mm
Seatpost RockShox Reverb Stealth 170 mm
Brakes MAGURA MT5 200/200 mm
Drivetrain SRAM GX Eagle 1x12
Stem Truvativ Descendant 40 mm
Handlebar Truvativ Descendant DH 800 mm
Wheelset DT Swiss H1900 27.5"
Tires Continental Der Baron Projekt 2.4"

Technical Data

Size M L
Weight 19.52 kg
Perm. total weight 130 kg
Max. payload (rider/equipment) 110 kg
Trailer approval no
Kickstand mount yes

Specific Features

customizable spec

**Very exposed**
With its “spacer”, the speed sensor on the chainstay is not only unattractive but also very exposed. If you get a branch in the rear wheel, you might have to ride home without support.

**Free upgrade**
NOX deliver the HeLIUM with 180 mm rotors as standard but an upgrade to 200 mm rotors is free of charge. Make sure you select the right rotor size when ordering your bike!

**Smooth operator**
The 170 mm RockShox Reverb is smoother, faster and more ergonomic than any other dropper in this test.

NOX HeLIUM geometry and sizing

While figuring out the right size for your HeLIUM, you should be careful. The bike is only available in size M and L, which means it’s not an option for either small or particularly tall riders. If you find yourself between the two sizes, you should take your inseam as reference, because at 478 mm, the seat tube of the size L could be too long for riders with short legs. With a 170 mm dropper, our shorter test riders were already at the limit. The seat tube is long and has a very progressive angle, despite the fact that the 74.5° seat angle is the slackest in this test. Without a pronounced kink in the seat tube, the seat tube angle doesn’t change when extending the post, as is the case with the Specialized and Lapierre. The result: even on steep climbs, the riding position is nicely centered and thus efficient. That’s also helped by the chainstays, which are approximately 2 cm longer than on the other two bikes.

Size	M	L
Seat tube	433 mm	478 mm
Top tube	610 mm	635 mm
Head tube	135 mm	135 mm
Head angle	65.0°	65.0°
Seat angle	74.5°	74.5°
Chainstays	453 mm	453 mm
Wheelbase	1,233 mm	1,259 mm
Reach	446 mm	470 mm
Stack	613 mm	617 mm

The shock tune doesn’t harmonise with the rear end. We recommend upgrading to a FOX X2 shock, which is the same as fitted to the Pro model.

**Helmet** Giro Montaro MIPS | **Glasses** Smith Wildcat | **Shirt** ION Traze Amp | **Shorts** ION Scrub Amp | **Shoes** ION Rascal Select

The NOX HeLIUM 5.9 All-Mountain Expert on test – modern geometry meets harsh suspension

That’s how we like it! The centred riding position of the NOX HeLIUM is spot-on. In combination with the updated firmware of the FAZUA motor, you can now rack up the vertical metres in relaxed fashion. But the NOX is also fun on more demanding climbs. The front wheel sticks to the ground even on steep sections and allows you to focus on your line. Especially in River mode, the FAZUA motor with the 2.0 firmware update is very natural and easy to modulate, yet delivers enough power at its peak to handle tricky passages. This is where the NOX outperforms both other bikes. However, in slippery conditions on damp terrain and loose gravel, the NOX will reach its limits. The stiff suspension tune and low profile Conti Baron rear tire can no longer generate enough traction.

In terms of suspension, the NOX is diametrically opposite to the Lapierre. The rear end and shock are quite stiff, particularly in the first part of the stroke. This means that the suspension remains neutral even when riding out of the saddle but struggles to provide traction on the way down. It’s particularly on blocked terrain like root carpets that the rear wheel seems to get stuck on every obstacle it comes across. Although the modern geometry integrates the rider well both up- and downhill, in wet conditions the rear-end is rather hard to control. Surprisingly, as soon as you pick up speed, the shock of the HeLIUM blows through its travel too easily on harsh landings and big hits. We previously already tested the NOX in its top-end configuration with a FOX X2 shock. This is available as an upgrade for the Expert model at an extra charge of € 300 and improves the suspension characteristics of the HeLIUM radically.

It’s a real shame that the rear end of the NOX HeLIUM didn’t cut it on the trail because we were actually very impressed with the geometry and most of the components of the bike – read all about it in our test of the Pro model. A simple shock upgrade will unlock the full potential of the HeLIUM! It’s only on really smooth, manicured flow trails with berms, rollers, jumps and, most importantly, without brake bumps, that the stiff, overdamped chassis seems to keep it together without passing on massive blows to the body.

Tuning tip: upgrade to the FOX Float X2 shock found on the Pro version (€ 300) | short riders should cut down the 800 mm handlebars

Conclusions

The NOX HeLIUM is full of potential. In our first test, the Pro model with FOX suspension and 29” wheels managed to convince us thoroughly. On this version, however, NOX haven’t managed to tune the RockShox shock properly. This and the 27.5” wheels let the bike fall far behind in this test. Too bad, because we’re pretty impressed with the powerful FAZUA motor and well thought out geometry.

Tops

superb riding position
good, customisable spec

Flops

rear shock tune
only two frame sizes
speed sensor is very exposed

You can find out more about at noxcycles.com

The test field