Extralite HyperStem O18 Stealth

Extralite HyperStem O18 Stealth

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Extralite HyperStem O18 Stealth oversize 31.8 mm +/- 18° stem. With only 61 gr. (60 mm) weight, is the lightest aluminum stem in the world but it's strong, stiff and safe at the same time. Fully 7075 Txx CNC machined with special gr.5 titanium bolts black PVD coated. Road, MTB (XC, Enduro) and Gravel use. 1.1/8" head tube standard. 60-70-80-90-100 mm length, black anodized color with black laser etches (Stealth look).  CH-01 Computer Holder as option. 100% Made in Italy.

Stem Length

Extralite HyperStem O18 Stealth with only 61 grams (60 mm length) is the lightest aluminium stem in the world. It fit oversize handlebars (31.8 mm diameter) and standard or tapered head tubes with 1.1/8" end. HyperStem height on the head tube is 38 mm and require 32 mm minimum head tube length over the headset to fix it. Reversible angle +/- 18°, 60-70-80-90-100 mm lengths, black anodized color.

Extralite HyperStem O18 Stealth

Black laser etches an black anodized aluminium with black bolts create a "Stealth" look, racing but elegant at the same time! HyperStem O18 Stealth is not a simple stem but a masterpiece of design and technologies. Clever design, high technologies and best materials are used to create this beauty.

Extralite HyperStem O18 Stealth

Its light weight doesn't affect stiffness and safety that are strengths of HyperStem O18 Stealth.

Extralite HyperStem O18 Stealth

HyperStem O18 Stealth is fully CNC made from a bar of forged 7075Txx Aluminium. Forging and special military heat treatment gives to stem body an incredible strength. Superfine 5 axles CNC machining assure perfect shape optimized for weight and also with smooth finishing ideal to increase fatigue life.

35 mm oversize body diameter, instead 30 mm standard stem diameter, increase stiffness in exponential way due to the moment of inertia of the section. so HyperStem O18 increase 40% torsional stiffness with less stress (-20%) so it's also more safe and will last for a longer time.

Extralite HyperStem O18 Stealth

Why other brands doesn't use the same HyperStem O18 Stealth technology? Because isn't so easy and cheap to produce a similar stem, other stems are usually made from a forged bar but this technology couldn't be used to make a stem which body diameter is larger than front clamp bolts circle diameter. The only way to go is the expensive fine CNC machining and Extralite makes this better than most other competitors.

Extralite HyperStem O18 Stealth

Front clamps are also CNC machined from a forged plate of aluminium, special heat treatments allow them to be light and strong at the same time. They looks minimal but they withstand alla safety and fatigue tests. They are one far from the other to increase torsional stiffness and minimize handlebar flexion.

Extralite HyperStem O18 Stealth

Every detail is considered, all the corners are smooth to avoid any handlebar damage (specially carbon fiber ones), bolts housing are precise to have a linear loads concentration without high load spots.

Extralite HyperStem O18 Stealth

Also bolts aren't standard, they're special made for HyperStem O18 Stealth, they're Gr.5 Titanium CNC machined with forged heads (Torx insert) and rolled threads so the best bolts you can make! Their special design, with the help of CNC machining, allows to save weight and minimize high stress spots. HyperStem Stealth bolts are black PVD coated. These are little details but for Extralite are very important!

Extralite HyperStem O18 Stealth

We always advise to use a precise torque wrench to tightening HyperStem O18 Stealth bolts. Torque specs are written on product user manual that comes with the stem and that you can also download here. We recommend to use anti-seize compound on titanium bolts threads and where they are in contact with aluminium stem parts to avoid oxidation.

HyperStem O18 Stealth clear and smooth design has also an ergonomic function because there aren't dangerous sharp edges that could hit rider legs. Anodized black finishing is light and durable, laser etched graphics too.

HyperStem O18 Stealth after FEM simulation, easily withstand severe UNI 10518 safety test, so it's light, stiff and affordable at the same time. These great results comes after 10 years of clever product developing. Many riders used and still using Extralite stems winning many races all over the world!

Extralite HyperStem O18 StealthVery high loads are required to broke an HyperStem, 5 times more than safety test standard! HyperStem O18 fatigue life is twice than its predecessor so it can be used also for more severe use like All Mountain and Enduro (of course for XC,  Road  Racing, Gravel and CX too!).

Extralite HyperStem O18 Stealth

Extralite produce HyperStem not only in O18 version but also O6 (+/- 6° angle) ; O12 (+/- 12° angle) and 1.25 version (+/- 6° angle for 1.1/4" head tubes). The table above show how the handlebar position change due to stem length and angle and can help you to make the right choice.

Extralite HyperStem O18 Stealth

Extralite produce an ultralight carbon fiber made computer holder specific for HyperStem, called CH-01, which adds only 15.8 grams to the stem weight. CH-01 Computer Holder comes with Garmin mount but is compatible with many other 2 bolts mounts like Blackbird, Bryton, Cateye, GoPro, iGSPORT, Omata, Polar, Sigma, Wahoo (you have to get yourself the specific mount for your computer). CH-01 Computer Holder could be purchased directly with HyperStem (as stem accessory), in this way you can save some money instead buy them separately.

Extralite HyperStem O18 Stealth is fully Made in Italy!

extralite made in italy

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Data sheet

Weight :
61 gr. (60 mm) - 65 gr. (70 mm) - 69 gr. (80 mm) - 74 gr. (90 mm) - 83 gr. (100 mm)
Bar clamp diameter :
31.8 mm Oversize standard
Length :
60-70-80-90-100 mm
Steer tube clamp diameter :
1.1/8" standard
Angles :
+/- 18° Reversible
Material :
Totally CNC from AL 7075 Txx
Finish :
Black anodized
Graphics :
Laser, black
Bolts :
Special CNC Grd5 Titanium
Fork clamp height :
38 mm
Use :
XC, Enduro, Road, CX, Gravel
Steering Tube fitting :
32 mm minimum height
Max tightening torque :
3 Nm


Extralite HyperStem

Extralite HyperStem User Manual

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