Known problems

Known problems

Most Stromer S-Pedelec components are developed by myStromer AG in collaboration with various brand manufacturers such as Pinion, Pirelli, TRP, Blubrake, etc., and manufactured by them for Stromer. Only a few are standard parts, such as the chain, belt, derailleurs, or cassettes. At the headquarters in Oberwangen, Switzerland, the bikes are pre-assembled and then delivered to the dealer, who takes care of the final assembly.

The interplay of diverse mechanical, electromechanical, and electronic components makes Stromer S-Pedelecs technically complex bikes. Complexity usually correlates with more problems and malfunctions. Therefore, there have been and continue to be various „work in progress“ issues throughout the model history: Some were or are self-inflicted, others are due to quality problems with suppliers. Some have been resolved, others continue to have an effect to this day, and new ones have been added.

• V1 / V1.1 / ST1: The power electronics integrated into the motor of the first 36V models were prone to overheating and failure. While relocating the power electronics to the MCU (Motor Control Unit) on the down tube solved the overheating issue, the controller remains susceptible to interference to this day.
• 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 issues, shutting off during rides, front brake disc problems, slipping belt, and poor assistance. All can be fixed – see here.
• ST7:
  • Temperature problems in S-mode.
    With the FW SUI 4.5.0.3 (5.3.2025) the allowed engine temperature in Sport mode was slightly increased so that it can be used for longer.
  • Omni Connection Problems 2G/4G
  • Sudden loss of support / Restart (when driving in the rain)
  • Rusting steering head bearings
  • Pinion gearbox not shifting
• 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 sometimes seem overwhelmed by modern bike technology (electrical, electronics, software, diagnostics, etc.). While they are happy to book the nice margins on the bikes, the training of mechanics and a well-stocked spare parts inventory seem less important. The result is inadequate diagnoses and repairs, as well as long workshop times. Furthermore, problems are quickly blamed on the e-bike with the customer, and the customer becomes a pawn between the dealer and the e-bike manufacturer.

For the sake of completeness, it should also be said that delivery times for spare parts – especially during the Corona period – were sometimes glaringly long and can still be today. However, this problem is not just a „Stromer problem“; other brands are not always convincing here either. The process for warranty clarifications through myStromer AG can also become a test of patience.

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

All components of Stromer S-Pedelecs come from suppliers who mostly produce them in a version specified by Stromer. The assembly of the bikes takes place at myStromer AG in Oberwangen, Switzerland. Quality assurance (QA) is important for operational safety and ultimately for the enjoyment of the Stromer. As many feedbacks show, there is still room for improvement here. Component failures and the resulting failures of the Stromer are the consequence.

At the dealership, the final assembly of the bikes takes place. Errors „built-in“ there—due to sloppiness, lack of training, or insufficient final inspection—often lead to dissatisfaction.

Self-inflicted design and construction flaws – such as the horn in the front wheel's splash zone, the Di2 charging port (ST5), or the wavy down tube cover – also fuel the dissatisfaction statistics. It's a real shame, as it's avoidable. You often read in posts: „Great bike, super, the Stromer is really fun... when it works.“

C: User side

On the user's side, there are also reasons that can lead to the power adapter failing:

• Inspections are not being carried out, especially the initial inspection after a few 100 km.
• Lack of, improper, or missing maintenance of the e-bike, especially the drivetrain.
• Tire damage is often caused by driving with underinflated tires.
• Cleaning with a pressure washer or hose: There is a risk of water entering the bearings, the motor, or the electrical/electronic components.
• No aftercare needed, especially after riding in the rain, off-road, or in winter on salted roads – this particularly applies to the drivetrain and brakes.
• No regular checks of wear parts such as chain, belt, or brakes.

Problems and their solutions

The following chapters are a collection of problems and possible solutions that are often read about 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!