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30-day money-back guarantee
Engineered & Designed by Rocker Parts
DE|EN

FAQs / Glossary – RocStem Stems

As of August 2025

FAQ

compatibility

What is an Ahead stem?

An Ahead stem clamps the protruding fork steerer tube. from the outside. Requirement: no external thread on the fork steerer tube.

Will your stem fit my bicycle? (Handlebar & stem dimensions)

Our stems fit 1⅛" (28.6 mm) fork steerer tubes. Handlebar clamps: 31.8 mm or 35 mm. Please check both diameters.

Not compatible: fully integrated cable routing by extension/Head tube – please be sure to check our ICR cable routing.

Is the stem approved for e-bikes?

Yes, for Pedelecs up to 25 km/h in the intended area of operation. Not released for S-Pedelecs (45 km/h).

 

Operation & Features

How does FlatFit™ technology work?

FlatFit™ holds the handlebars in place during sideways swiveling. flat. This means the bike fits better in the rear garage of a motorhome, for example. without tools.

Because of the angled fork, the handlebars rise when swiveling. Our geometry This automatically compensates for 10° – depending on the handlebar width, this reduces the altitude gain by up to approximately 7 cm - that will be with the patent application FlatFit™ technology reached.

What does the two-finger rule mean for the RocStem stem?

To ensure your stem is securely in place, the clamping lever must be adjusted with the correct preload.
We recommend the following Two-finger ruleThe lever should move with two fingers Just barely able to open.

  • With just one finger If it is not possible → then the preload is too weak.

  • With more force than two fingers → The preload is set too high.

This ensures that your stem clamps reliably, but can still be operated comfortably and without tools.

What does LiftFix mean?

LiftFix secures the height Simple and tool-free. The locking mechanism prevents unintentional adjustment the height adjustment.

What is the EC preparation (Equipment Clip)?

All the extensions are prepared to Accessory mounts Easy to retrofit (adapters required).

What is the difference between a rotating and a swiveling stem?

Some manufacturers call it "rotatable", we call it swiveling – technically it's the same principle: the handlebars are moved sideways to save space.

What can I do if there's a noise (creaking or squeaking) coming from the stem?

Under unfavorable conditions, noise can occur at the joints. In this case, a light spray of chain lube (bicycle/motorcycle) into the pivot joint will help to make the movements quiet and smooth again. Please use sparingly and avoid contact with braking surfaces.

Does the handlebar remain stable in the swiveled position, or can it twist?

The stem locks automatically in the 90° position.
The integrated AutoLock-This function ensures a defined, stable handlebar position – no wobbling and no independent twisting.

 

Materials & Manufacturing

What are the differences between EN AW-6061 and EN AW-7075?

6061: proven, robust lightweight metal. 7075: high-strength Aerospace-grade material for maximum stiffness at low weight. We use the material depending on the component requirements.

What do I need assembly paste for?

Our assembly paste ensures more Slip resistance between the stem and steerer tube, and between the stem and handlebars. This ensures everything sits securely and stably, preventing unwanted twisting. At the same time, the paste protects the surfaces and facilitates later disassembly.

How do you produce (CNC)?

We manufacture on modern 5-axis CNC machines for precise fits. 

What does Edgeless mean?

Edgeless means: no sharp edges not at the handlebar clamp, but chamfers/radii – reduces notch effect, protects the handlebar.

 

Security & Permissions

How safe is the swivel mechanism (SLS)?

SLS uses a Safety latch in the tensioning lever and a double fixing of the shaft clamp. That prevents unintentional opening and increases operational reliability.

For which uses are your extensions approved – and for which are they not?

Approved for: roads, dirt tracks, forest paths, easy terrain.

Not recommended:

– Jumps > 50 cm

– Downhill, bike parks, trick riding, difficult singletrack trails

– Large handlebar bags > 2 kg / heavy front racks.

Why not mount it on carbon fork steerer tubes?

We advise against mounting our stems on carbon steerer tubes because carbon is more sensitive to concentrated clamping loads. Our stems could potentially generate higher or more localized stresses that could damage the carbon steerer tube (e.g., due to height adjustment or extension length). For safety reasons, we therefore recommend using only aluminum steerer tubes.

Does a stem require TÜV/CE/ISO/DIN certification?

Bicycle components are not subject to mandatory CE marking or TÜV testing like automotive components. Our products undergo rigorous quality control and are suitable for the stated application. We adhere to ISO4210.

 

Ordering & Packaging/Reviews

What is the mandate reference for SEPA direct debit?

Account holder's name in lowercase followed by one word, e.g., maxmustermann.

How do you ensure the authenticity of reviews?

We check and clearly mark reviews (e.g., order reference/verification). Details in our review information.

Do you avoid plastic packaging?

We reduce plastic as far as possible; if necessary, we use recycled materials.

GLOSSARY

A

Ahead

An Ahead stem grips and clamps the protruding steerer tube from the outside. The steerer tube must not have external threads.

Aluminium EN AW-6061

A proven, high-strength aluminum that is primarily used in vehicle construction.

Aluminium EN AW-7075

A very high-strength aluminum alloy used particularly in vehicle manufacturing and aerospace. It is ideally suited for highly stressed components.

boom length

Distance from the center of the fork steerer tube to the center of the head tube.

AutoLock

Automatic locking of the stem in the 90° position for a stable handlebar position without twisting.

B

Backsweep

The angle of the handlebar grips relative to the handlebar's center axis. This influences handling, for example, by allowing for a relaxed position of the elbows and hands. An angle of 5° to 8° is optimal.

Reviews

Information on the authenticity and verification of our customer reviews.

C

CNC

CNC (Computerized Numerical Control) machines manufacture components with the highest precision. Our components are produced on modern 5-axis machines.

E

E-bike

An e-bike is powered exclusively by an electric motor (without pedal assistance). Helmets and insurance are mandatory.

EC (Equipment Clip)

Universal accessory interface for all RocStem stems, compatible with lights, speedometers, navigation systems, and action cameras. Retrofittable on all models.

Edgeless

„"Edgeless" means that the handlebar clamps have no sharp edges, but rather rounded transitions. This reduces stress concentrations and protects the handlebars.

F

FlatFit™ technology

Our patent-pending FlatFit™ technology ensures the handlebars stay flat when swiveling. This allows the bike to fit better in low spaces – without modifications or tools.

H

Height adjustment

The height adjustment describes the one-time, tool-related adjustment of the handlebar height during assembly.
It is not a quick-adjustment feature for everyday use – only the swivel function of the handlebars can be adjusted without tools.

K

Cable routing through the steering bearing (ICR)

In this design, brake and shift cables run directly through the headset into the frame. This creates a clean look, but can restrict the handlebar's range of motion with swivel stems.

The Cable routing ICR Rocker Parts guides the cables past the pivot area without kinks, so that the handlebars remain freely movable.

Plastic-free packaging

We avoid using plastic in packaging wherever possible. Where necessary, we use recycled materials.

L

Handlebar diameter

Common handlebar diameters at the stem clamp are 25.4 mm (1"), 31.8 mm (1⅛"), and increasingly 35 mm. The grip area is usually 22.2 mm.

Steering angle compensation

The steering angle of a bicycle causes the handlebars to rise when turning. Our special geometry (FlatFit™ technology) compensates for this by 10° – reducing the rise by up to 7 cm, depending on the handlebar width.

LiftFix

The LiftFix system prevents unintentional adjustment of the height setting.

M

Mandate reference (SEPA)

For the SEPA direct debit scheme: enter the account holder's name in lowercase as one word (e.g. maxmustermann).

MAX

Label for our stems with the patent-pending FlatFit™ technology.

Assembly paste

Special grease with microparticles, used on stems and handlebars. It increases slip resistance, protects surfaces, and facilitates disassembly.

P

e-bike

An electric bicycle with pedal assist. It is powered by a combination of muscle power and a motor. Maximum speed with assistance: 25 km/h.

TÜV, CE, ISO, DIN testing

Unlike car manufacturers, bicycle stems are not subject to mandatory CE marking or TÜV approval. However, our stems undergo rigorous quality testing and are developed according to ISO 4210 standards.

R

Rise

Rise refers to the height difference of the handlebars. This allows you to adjust the cockpit position. A higher cockpit promotes a more relaxed riding posture.

S

stem

A stem is inserted into the steerer tube and clamped from the inside. The minimum insertion length must be observed.

SLS (Safety Locked System)

Safety mechanism of our swiveling stems. An additional latch prevents unintentional opening, and the double stem clamp increases stability.

S-Pedelec

A pedelec with motor assistance up to 45 km/h. A Class AM driver's license is required, as well as insurance and helmet.

U

UpSweep

The angle of the handlebar grips should be upwards. An angle of 3° to 8° is optimal to promote an ergonomic wrist position.

By the way...

…we at Rocker Parts speak to you directly – clearly, simply, and without any frills. We're not about twisting words or sugarcoating things, but about talking to each other honestly.

One thing is paramount for us: respect. Everyone is welcome – regardless of whether you are a woman or a man, young or old, regardless of origin, religion or sexual orientation. We believe in genuine togetherness, not in pigeonholing.

And because we prefer to invest our energy in good products rather than language debates, we consciously avoid complicated gender-inclusive language. Because in the end, it's not the perfect wording that counts, but what we do: delivering quality, being open, and remaining fair.

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