Known problems

Known problems

Most Stromer S-Pedelec components are developed by myStromer AG in cooperation with various brand manufacturers such as Pinion, Pirelli, TRP, Blubrake etc. and manufactured by them for Stromer. Only a few are standard, e.g. the chain, the belt, derailleurs or cassettes. The bikes are pre-assembled at the headquarters in Oberwangen, Switzerland, and then sent to the dealers. They do the final assembly.

The interaction of various mechanical, electromechanical and electronic components makes Stromer S-Pedelecs technically complex bikes. Complexity usually correlates with more problems and faults. This is why there have been and still are various "construction sites" in the history of the model. Some of them were or are homemade, others are due to quality problems on the part of suppliers. Some have been solved, others continue to have an effect to this day, and new ones have been added:

• V1 / V1.1 / ST1: The power electronics integrated in the motor of the first 36 V models tended to die of heat. The relocation of the power electronics to the MCU (Motor Control Unit) on the down tube solved the heat problem, but the controller is still prone to faults today
• Missing Moisture protection (shrink tube) of the three motor cables in the bottom bracket area on older models (before 2018)
• ST2 Belt: The ST2 Belt had various teething problems: Shifting problems, switching off while riding, front brake disk, belt slipping, poor support. All can be solved - see here.
• ST7: Temperature problems in S mode. With the FW SUI 4.5.0.3 (5.3.2025), the permitted engine temperature in Sport mode has been slightly increased so that it can be used for longer.
  Omni connection problems 2G/4G | Sudden off when driving in the rain | Rusting steering head bearings | Pinion gearbox does not shift
• ST5/ST7: Creaking in the steering headRelubrication of the upper bearing shell
• Brakes: Squeak.... Good advice is expensive
• GPS tracking: It is still inaccurate in driving mode and not up to date. It is ok in theft mode. With the FW SUI 4.5.0.3 (5.3.2025) is expected to bring about improvements here.
• Driving dynamics: Support problems and the TMM sensor are still part of a retailer's day-to-day business today
• Rims: AlexRims: Clack caused by the rim impact; Cracks for the spoke holes
• Rims: Rodi: broken spokes
• Tires: Blisters and cracks with the Pirelli cycle-e ST tires
• Shimano Di2: Inconveniently positioned Di2 charging socket in the bottom bracket area on older ST5 models (now rectified)
• Corrugated lower tube cover: There is now a revised version
• Motor coating is coming off. Models from mid-2024 should have a new powder coating that is more resistant to corrosion
• Pinion models: Partial problems with Rust in the steering head bearings. There is a new bearing shell with water drainage openings

If you read the Stromer forums and fb groups, three aspects jump out at you:

A: Service quality of the retailers

Dealers often seem overwhelmed by modern bike technology (electrics, electronics, PC, fault analysis, etc.), which leads to inadequate diagnoses, repairs or long workshop times. Customers are quickly blamed for the problems on Stromer.

The delivery times for spare parts, especially in the Corona era, were blatantly long, but not only at Stromer! Dealers with little or no stock of spare parts could not - and still cannot - carry out repairs quickly. The warranty clarification process via myStromer AG can also be a test of patience.

B: Quality control at myStromer AG, the parts suppliers and dealers as well as "clumsy" engineering

All components of the Stromer S-Pedelecs come from suppliers who usually manufacture them in a version specified for Stromer. The bikes are assembled at myStromer AG in Oberwangen, Switzerland. Quality assurance (QA = quality assurance) is important for operational safety and ultimately enjoyment of the Stromer. As a lot of feedback shows, there is room for improvement here. Failures of components or the Stromer are the result.

The final assembly of the bikes takes place at the dealer. Errors 'built in' there due to 'sloppiness', a lack of training and also a lack of final inspection often lead to resentment.

Self-inflicted design and construction faults (e.g. horn in the splash water area of the front wheel, Di2 charging socket (ST5), wavy down tube cover...) also contribute to the displeasure statistics - actually a pity as they could have been avoided.
You often read in posts: "Great bike, super, the Stromer is really fun... when it rides..."

C: User side

There are also reasons for the Stromer to fail on the user side.

• Inspections are not carried out, especially the initial inspection after a few 100 km.
• Inadequate, incorrect or no maintenance of the Stromer. This applies in particular to the drivetrain.
• Damage to the tires is often caused by riding with too little air.
• Cleaning with high-pressure cleaner or hose. You run the risk of water penetrating the bearings, motor or electrics/electronics.
• No aftercare, especially after driving in the rain, off-road or on salted roads in winter. Especially applies to the drivetrain and brakes.
• No regular inspection of wearing parts, e.g. chain, belts, brakes.

Problems and their solutions

The following chapters are a collection of problems (and possible solutions) that can be read about again and again or that I have experienced myself.

• Rechargeable battery, battery
• Brakes
• Electrics & electronics
• Error and warning messages
• Chain (sprocket) Pulleys and belts
• Motor
• Omni
• Tires / Rims
• Circuit
• Smartlock
• Miscellaneous

Have you experienced something with your Stromer that is not described here? Use the comment field below or contact/feedback for your feedback!