When people talk about the best eBike motors, the conversation usually centres on power, torque, weight, and noise. Yet a more fundamental question is often overlooked: reliability. A motor that feels impressive on a short test ride quickly loses its appeal once it starts causing problems.
As I reviewed the available studies and large rider polls, I was struck by how often eBike motors are replaced. Across multiple datasets, roughly 20 to 40% of riders experienced failures severe enough to require a full motor replacement. In one poll, 6% of riders reported replacing their motor between two and four times on the same eBike.
This frequency of failure simply shouldn’t be considered normal, as these failures come with real consequences. Beyond the frustration, they waste time, generate unnecessary electronic waste, and reduce resale value.
It shouldn’t be controversial to say that the best eBike motors aren’t the most powerful or the lightest – they’re the mid-motors you can rely on to keep turning, year after year.
Does the Industry Have a Problem with Unreliable Mid Motors?
I was genuinely shocked when I started digging into just how often ebike motors fail.
- A Facebook poll of 1,700 riders conducted by EMBN found that 23% had their motor repaired or replaced under warranty.
- A survey of over 800 eMTB owners produced similar results, with roughly 25% of motors needing replacement, and some brands exceeding a 30% rate (I’ll analyse this survey below).
- A poll of 222 riders, 33% reported replacing at least one motor on their current eBike.
- In an EMTB forum poll of 108 Specialized eMTB owners, around 40% had a motor failure that resulted in replacement.
- A study of 466 riders revealed that certain motor models had failure rates over 40% (I’ll analyse this study below).
Even if you ignore the frustration of a broken motor, this is incredibly wasteful. Research from E-Waste Monitor indicates that only 22.3% of electronic waste was formally collected and recycled in 2022. Poorly managed e-waste not only harms the environment but also poses health risks to workers handling it.
Reliability issues also mean wasted time. A motor failure mid-ride leaves you scrambling to reach your destination by other means. Your bike then spends days (or even weeks) in a workshop, and you waste additional time dropping it off and picking it up.
More reliable motors would also preserve resale value. A dependable motor makes the high cost of ebikes easier to justify, boosts second-hand value, and ultimately benefits both the industry and consumers.
It’s become clear to me that the best eBike motors aren’t the ones with the highest power, smallest size, or quietest operation – they’re the ones you can actually rely on.
Consumers Want Reliable eBike Motors
Putting aside waste, time, and resale value, reliability is what riders care about most.
E-MOUNTAINBIKE magazine surveys its readers annually to track eBike preferences. In 2025, responses from 15,000 participants showed that most riders aren’t chasing ultra-powerful motors – they want motors they can trust. A notable 58% of readers said motor reliability is important, which was more than any other motor characteristic (eg. torque, weight or how it feels).
So… why aren’t ebike motors more reliable?
Why Aren’t eBike Motors More Reliable?
There are many reasons why an eBike motor might fail. The most common culprit is water or dirt getting into the bearings or electronics, but overheating, pedal strikes, and poorly managed electrical power (whether by design or due to faults) can also cause problems.
In theory, sealing a motor well is straightforward during the design phase. In practice, effective seals add drag, which directly reduces battery efficiency. As a result, manufacturers are often reluctant to sacrifice range for better water resistance.
Meanwhile, motors are getting smaller, lighter, and more powerful. That often means smaller gears and bearings, which are less tolerant of water, grit, and impacts.
In addition, it’s difficult for a brand to sell a larger and heavier (but more durable) motor when competitors are chasing lighter, more powerful designs. This race for impressive specs often pushes long-term reliability down the priority list.
So, which eBike motors are the most dependable? Let’s look at the data.
eBike Motor Reliability Studies and Polls
Before diving into the data, it’s important to acknowledge a few limitations inherent to motor reliability polls.
Firstly, poll participants may be more inclined to respond if their motor had already been replaced, introducing a self-selection bias.
Secondly, the data is inevitably backward-looking. Riders need time to buy eBikes and accumulate meaningful mileage, so by the time failure statistics emerge, many of the motors in question are already older or discontinued. Whether the latest iterations or brands (eg. Avinox or TQ) have improved reliability is unknown. In that sense, we’re always looking in the rear-view mirror.
Still, if you’re forced to bet on durability, brands with a strong historical track record remain the safer choice.
Finally, we have very limited insight into how these motors were actually used. Factors such as total mileage, riding style, maintenance practices, service intervals, terrain, gradients, assistance modes, weather exposure, washing habits, storage conditions, and vibration all influence longevity – and the impact of each varies widely. None of this nuance is captured in polling data.
Wertgarantie eBike Motor Reliability Report (2021)
In 2021, a collaboration between insurance provider Wertgarantie and research institute Statista published a study examining the reliability of eBike components. Drawing on data from more than 2,000 customers, the study found that 466 riders (around 22%) had experienced technical issues with their eBikes.
Although the study does not specify usage patterns, most bikes in the dataset were likely used primarily in the city. This assumption is based on the two highest-rated bike models for overall satisfaction, both of which were city eBikes.
Among riders who reported technical problems, battery issues were the most common, accounting for 43.8% of failures. Motor-related problems followed closely at 38.2%, while display failures affected 27.7% of bikes.
When looking specifically at motors, failure rates vary significantly by brand and model. The strongest reliability results come from long-established manufacturers that favour conservative, proven engineering. Yamaha, Giant (using Yamaha-built motors), and Bosch consistently rank at the top due to mature designs.
At the model level, the Yamaha PW-ST stands out, with technical problems affecting just 4.3% of cases. Other strong performers include the Giant SyncDrive Sport, Bosch Performance Line, Fischer Silent Drive, and Bosch Active Line Plus. By contrast, the Brose Drive S Mag mid-drive motor and the Shimano Steps E6100 both show technical issue rates exceeding 40%.
Wertgarantie eBike Battery Report (2021)
According to the Wertgarantie study, batteries – not motors – are the most common source of technical issues. In 2021, battery failures affected 43.8% of the 466 riders who had technical problems, dropping slightly to 40.9% by 2024.
The top-performing batteries achieved 96% reliability, while the lowest-ranked were reliable an abysmal 35% of the time (hopefully, the Shimano E8014 batteries were redesigned and replaced under warranty!).
Giant and Yamaha led the pack, with only 6 to 8% of their batteries experiencing technical issues. Bosch followed, with 11 to 14% of units affected, and Shimano trailed further behind, with around 24% of batteries showing problems.
Wertgarantie eBike Reliability Report (2024)
In 2024, Wertgarantie published a follow-up report confirming that motors remain a significant source of eBike technical failures, although their relative share has declined over time.
Where motors accounted for roughly 38% of reported defects in 2021, their share had fallen to around 24% by 2024. This shift could reflect improving motor reliability, changes in usage patterns, or a redistribution of failures across other components rather than a simple reduction in overall defects.
Unfortunately, the 2024 report does not break failures down by motor brand or model.
Norwegian eBike Motor Reliability Poll
We can now turn to a dataset that offers more relevant insight into eMTB motor reliability.
This poll, conducted within a Norwegian eMTB Facebook group, gathered responses from 817 eMTB owners and found that 201 had their motors replaced under warranty – equating to a 24.6% replacement rate. This figure is notably higher than those reported in the Wertgarantie study, but the difference is not surprising.
eMTB motors are typically subjected to far harsher conditions: steeper gradients, frequent acceleration, sustained high loads, and significantly more vibration and impact. The poll was also conducted in Norway, where cold temperatures, moisture, and exposure to water and dirt may further influence motor durability. As such, the results provide a useful indication of which motor brands are more tolerant of neglect, environmental exposure, and hard off-road use.
The lowest warranty replacement rates were observed for Yamaha (17.3%), Bafang (17.6%), and Bosch (22.4%). The highest rates came from Brose (31.8%) and Shimano (27.8%). Notably, Brose’s warranty replacement rate was almost double that of Yamaha or Bafang and nearly 50% higher than Bosch. Any datasets with fewer than 30 responses can be excluded, as sample sizes that small risk producing misleading conclusions.
However, a few factors could influence these numbers.
- Participants may have been more likely to respond if they had a motor that had been replaced (self-selection bias), so the overall 24.6% average warranty replacement rate could be slightly higher than the true average.
- The three most reliable brands (Yamaha, Bafang, and Bosch) provide spare parts and are serviceable at eBike motor centres, meaning many problems may have been repaired rather than requiring a full replacement.
- And Norwegian consumers also benefit from a five-year warranty on motors, batteries, and electronic components under the Consumer Purchases Act. This extended coverage allows motor replacements over a longer period than is typical in most other countries.
The Best eBike Motors For Reliability
Yamaha & Giant
Yamaha Motors (and Giant models that use Yamaha-built drive units) consistently rank among the most reliable on the market.
In the Wertgarantie study, the Yamaha PW-ST topped the list, with only 4.3% of motors experiencing technical issues, while the Giant SyncDrive Sport came in second at 6.4%. Similar reliability trends were seen with Yamaha and Giant batteries.
Yamaha also led the Norwegian eMTB motor poll, with just 17.3% of motors requiring a warranty replacement – well below the 24.6% average across all brands.
One clever feature of Yamaha motors is a small breathable membrane that allows moisture inside the motor to slowly escape over time. Most other motors lack this feature, so any water that gets in can remain trapped, potentially causing damage.
That said, reliability doesn’t mean maintenance-free. Bearings and internal components wear and corrode over time, and factory grease can dry out, making a clean-out and re-lubrication necessary. The grease on the freewheel pawls can also become sticky, preventing proper engagement with the ratchet and potentially damaging the freewheel mechanism and steel drive gear.
Yamaha and Giant are sometimes slower to process warranty replacements, possibly because failures occur less frequently in the first place. As a result, while their motors and batteries are generally robust, an issue can leave you without a bike for longer than some other brands.
Bosch
Bosch is the most widespread eBike motor brand, and that popularity is backed up by solid reliability data.
In the Wertgarantie study, only 6.5 to 11.8% of Bosch users reported technical issues, and in the Norwegian eMTB motor poll, Bosch’s warranty replacement rate (22.4%) came in below the overall average (24.6%).
Bosch motors are not designed for routine servicing and are typically only repaired if a problem arises. They are generally engineered for longevity, with larger gears and bearings than many competitors. A Bosch motor kept dry can easily surpass 80,000 km without issues. Most people I’ve spoken to suggest the Performance Line CX Gen 2 is the most reliable version of the lot.
Water ingress is the main vulnerability, but aftermarket seals and protective shields can greatly reduce this risk. According to Pete Collard of the eBike Motor Centre, once aftermarket seals are fitted to a Bosch motor, “we never see it again”.
When it comes to warranty replacements, Bosch sits in the middle of the pack: if a failure does occur, you won’t wait indefinitely, but turnaround times aren’t as fast as some other brands.
Bafang
Bafang motors are generally regarded as robust, dependable, and well-built.
In the Norwegian eMTB motor poll, they required warranty replacement 17.6% of the time, placing them effectively level with Yamaha (17.4%), better than the top-5 average (24.6%), and clearly ahead of Bosch (22.4%).
From a design perspective, Bafang motors are well sealed internally, but the externally exposed crankshaft bearings are a known weak point and often fail due to water ingress. While there’s no permanent solution to prevent this, the bearings are relatively straightforward to replace.
One major advantage of Bafang systems is parts availability. Virtually all internal components are readily available on the aftermarket, making Bafang motors the most DIY-friendly option for servicing and repair.
That said, Bafang’s warranty service and dealer support can be inconsistent. In some areas, it’s excellent, while in others, it can be nearly non-existent. So even though Bafang motors are reliable and rebuildable, they’re best used in regions with strong local support.
How You Can Help With eBike Motor Reliability
Some simple steps can help make any eBike motor more reliable:
- Wash your bike upright, not on its side.
- Store your bike upright, in a dry area.
- If you transport your bike behind a vehicle, ensure the motor is covered if the roads are wet.
- Do not direct a water hose at the motor, especially the crankshaft area.
- Never pressure wash your bike.
- Do not ford any water deeper than the bottom of the motor.
- Pedal at a higher cadence (RPM).
- Store your battery indoors overnight (protected from weather/temperature).
- Use batteries that are hidden inside the frame for protection from crashes and weather.
Summary
Everyone talks about power, torque, or weight when judging eBike motors – but the truth is, the best eBike motors are built around reliability.
According to the data available, Yamaha, Giant, Bosch, and Bafang consistently show that durability can go hand in hand with performance.
But which motors are the easiest to service and repair? I’ve also explored the most serviceable and repairable eBike motors – perfect to cross-reference with the reliable models you’ve read about here.