Nicolai Helius AC frame review

Super surefooted handbuilt hammer bike

Our rating 
4.0 out of 5 star rating 4.0
GBP £1,800.00 RRP

Our review

Super stable, neutrally suspended trail tank with mid-wheel speed and fantastic handbuilt quality for the price
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Nicolai’s 18th birthday bike looks retro but sticks to the trail with a state of the art shape and smoothly neutral, shock tune specific suspension.


Ride and handling

The round tubes and CNC machining might look retro, but there’s nothing old school about the slack 66.5-degree head. The bottom bracket drops the cranks well below the axle centres for a ‘sat into the bike’ ride character.

Long chainstays add even more surefooted speed stability and railing confidence to the Nicolai at speed. There is some flex from the skinny fork but, despite the appearance of the unbraced mainframe and seatstays, the frame tracks fine and it never felt as though it was going to wander dangerously off line or twang us high-side once committed into a corner.

There’s certainly enough clear feedback to make use of the generous tyre grip, and the slightly larger wheel size also extends the time you’ve got to go with a sideways drift or counter steer it back under control. The long wheelbase and back end mean it’s not a natural hop-and-pop machine though, and even with relatively light wheels it’s more plough-like than playful.

Unlike many German bike makers whose wares we test, Nicolai have specced a properly progressive race style tune, helped no doubt by the fact that several of the RockShox in-house suspension specialists and downhill racers we know run Nicolais as their own bikes. This firm and tightly controlled ride really underlines the cornering stability at speed and turns the AC into a proper berm railer at the expense of a more bouyant, floated ride.

Experience from our Helius long-termer tells us whatever tune you choose will be obvious in the end result rather than limited in potential range by the axle path/linkages. The fact you have such a long stroke and relatively low overall (1:2.38) leverage to play with, plus the extra damping oil capacity of the piggyback reservoir also means patient set-up can be rewarded with properly outstanding and consistently neutral control.

While our sample was running a single chainring, granny or big ring use doesn’t disturb pedalling to any noticeable extent. Even the biggest handful of brake still leaves the back end free to move rather than jacking it up and slamming it into stuff.

The more rounded axle path and long chainstay does mean the back end hangs up occasionally on square-edged hits, and it doesn’t pump as naturally as more rider-interactive bikes either. There’s very little kickback through the pedals though so traction is consistently excellent and you can put down power at any point rather than having to feather it through your feet on rocky, rooty climbs.

The long tail end also means no unwanted front wheel pop up, and despite the super short stem and slack head we had excellent control and consistent grip through both wheels on really steep, technical scrambles.

Frame and equipment

Nicolai’s trademark straight round tubes with crisp, CNC-machined junction sections and terminals look old school – but there’s no doubting the skill and framebuilding diligence that creates the massive welds.

Nicolai helius ac:
Steve Behr

The Helius AC’s frame is an exercise in old-school craftsmanship

The Stealth seatpost-routed, ISCG05 mount-equipped frame is topped and tailed with a ‘Conehead’ tapered head tube and perfectly alignment compensated RADO dropouts for the 142x12mm axle.

A lack of seatstay bridge and big machined chainstay yoke gives masses of tyre room while the Nicolai head badge and proud ‘Made in Germany’ chainstay text are machined into the metal itself.

There is a vast range of ultra thick paint or tough anodised finishes, and full or semi custom geometry is also available for an upcharge. Considering the amount of work that’s gone into each frame, standard prices are an absolute bargain and our long-term experience confirms the phenomenal durability of the paint and pivots even in the worst conditions.

Nicolai only sell frames, but most Nicolai dealers are custom build specialists. The responsiveness of our sample was boosted by SRAM XX1 11-speed transmission, saving 911g over Shimano Deore for £997 more.


Avid X.0 Trail brakes, Stan’s rims, Hope hubs and headset and Maxxis High Roller II front and Ardent rear tyres are all favourites too. The Maximum control Holzefeller stem and Boobar cockpit were gagging for a 35mm legged Pike fork rather than the flexy 32mm Revelation though.

Product Specifications


Name Helius AC 650 frame (13)
Brand Nicolai

Description S, M, L, XL*, XXL
Rear Shock RockShox Monarch Plus RC3
Tyres F: Maxxis High Roller II EXO 27.5x2.35in, R: Maxxis Ardent EXO 27.5x2.25in
Weight (lb) 28.8
Weight (kg) 13.1
Stem Truvativ Holzefeller 50mm
Shifters SRAM XX1 trigger
Seatpost RockShox Reverb Stealth
Seat Angle 74
Saddle WTB Silverado Ti
Rear Wheel Weight 2250
Rear Derailleur SRAM XX1
Bottom Bracket SRAM XX1
Headset Type Hope
Head Angle 66.5
Handlebar Truvativ Boobar 780mm
Front Wheel Weight 2020
Front Derailleur SRAM XX1
Frame Material EN 7005 alloy with EN 7020 machined sections, 138/150mm (5.4/ 5.9in) travel
Fork RockShox Revelation RCT3 Dual Position, 150mm (5.9in) travel
Cranks SRAM XX1 30T
Cassette SRAM XX1 10/42T
Brakes Avid X.0 Trail, 200/180mm rotors
Front Wheel Stans ZTR Arch EX 650B rims on Hope Pro II Evo hubs