Testy chłodzenia TSDZ2

Testing gear:

Temperature sensor mounted on the outside of the TSDZ8 motor cover


48V (13S) 17.5AH battery with Bluetooth BMS to read the power draw data


40W desk fan


Test setup:


Trainer tests methodology:

There were two main tests conducted using the bicycle trainer.

The first test was to determine whether the motor has any temperature safety features implemented. The test was conducted at full power, which is around ~1100W (~22A). Without any active fan cooling (no airflow). The temperature limit was set at 70°C.


The motor controller can draw up to 24A from the battery. The exact power figure depends on the battery voltage. The maximum power does not exceed 1150W.

The second test was conducted at about ~750W (~15A). With the fan set at its maximum setting blowing air directly at the front of the motor. 


Both tests were conducted at cadences around 90 rpm.

Stress test of TSDZ8 48V motor at full power of 22A (1100W) and cadence of 90 without any airflow:

Stress test of TSDZ8 48V motor at full power of 22A (1100W) and cadence of 90 without any airflow

The motor reaches 70°C after 7 minutes and 46 seconds. After cutting the power the temperature still rises to 72.3°C. Cooling down to 54°C takes 9 minutes and 40 seconds. Cooling down without any airflow takes a long time.

The temperature was measured on the outside of the motor cover. The motor itself reached a higher temperature than 72.3°C. No temperature safety feature was engaged during this test. When taking apart the motor, we saw no temperature sensors inside. This test confirms that the motor is not protected against overheating. Any users wanting to squeeze the maximum power out of these motors should consider installing additional temperature protection. It can be a bimetal temperature sensor acting as a cut-off and connected to the brake signal in the controller.

With a power draw of 1071W from the battery, the trainer showed a power output of 781W. Motor efficiency (including drivetrain losses) was around 73%.

TSDZ8 efficiency

Stress test of TSDZ8 48V motor at 15A nominal power (750W) and cadence of 90 with maximum fan airflow:

Stress test of TSDZ8 48V motor at 15A nominal power (750W) and cadence of 90 with maximum fan airflow

The initial temperature reading was 26.5°C. The motor's cover heated up to 48.2°C after 21 minutes and 11 seconds. We stopped the stress test because the temperature readings almost stopped rising at this level. The motor, at rated power with the maximum fan airflow, shows no tendency to overheat. The heat capacity appears to be large enough that typical use at this power level should not result in overheating.

With 750W drawn from the battery, the trainer recorded a power output of 547W. Motor efficiency (including drivetrain losses) was around 73%.

TSDZ8 efficiency

Comparing TSDZ2 (TSDZ2B) to TSDZ8, this is a huge improvement. The previous generation of motors from Tongsheng were not able to maintain nominal power levels (500W) without overheating after only a few minutes. Only with full cooling mods and running the open source firmware (OSF), these motors were safe to use at the manufacturer's declared power level - 500W (because the actual nominal power figure is lower).

Assistance levels:

The biggest advantage of the TSDZ2/TSDZ2B motors is the open-source firmware, which allows you to customize the motor's parameters. You can set the assistance power at any level and change the modes according to your needs. 

Unfortunately, the original TSDZ8 firmware lacks this functionality. This results in the fact that the assistance levels are not scaled correctly. The first two levels are scaled incorrectly against the torque sensor readings. The assistance from the motor is only a fraction of the power that is pushed into the pedals. With a gentle ride and low power transferred to the cranks, there is almost no assistance. Only with a higher load or an uphill climb, there is some significant assistance, but it is a result of the greater power transferred to the cranks. It is poorly scaled on the first and second assistance levels. The third level works great, but it is too powerful for someone who wants to go slower and have less assistance.

The first assistance level reaches a maximum of ~3A. Reaching this value requires several hundred watts pushed into the cranks by your legs. For a slower ride, the assistance is not noticeable. 

Below you can see the maximum power drawn from the battery compared with the power reading from the trainer. The power from the battery has to be decreased by the efficiency of the motor (~73%). You need to output 500W with your legs to get about 120W of assistance.

TSDZ8 first level assistance

To better understand the problem. With 180W being generated from the legs, there is no assistance in the first mode.

TSDZ8 first level no assistance

The second assistance level reaches a maximum of ~6.5A. Reaching this value requires several hundred watts pushed into the cranks by your legs. For a slower ride, the assistance is not noticeable.

Below you can see the maximum power drawn from the battery compared with the power reading from the trainer. The power from the battery has to be decreased by the efficiency of the motor (~73%). You need to output 500W with your legs to get about 250W of assistance.

TSDZ8 second level assistance

The third level assists up to a maximum power of ~24A. These are peak power levels during acceleration or high load. Typically it draws 6A-12A depending on the load, power put into pedaling, and cadence. This level works very well, but can be too powerful for someone who wants to ride slower, put more effort into pedaling, or get more range from the battery. Therefore, the first two levels must be scaled correctly. 

The fourth assistance level works similarly to the third one and outputs a max power of ~24A. The difference is that more power is provided more quickly than in the third level. Typical power draw is also slightly higher than on the third level. In short, it is a little more powerful than level three, but it also works very well.

The fifth level of assistance. It is available on the 860C display. It is a copy of the fourth level. No significant difference can be felt here.

Firmware update (04.03.2024)

We contacted the Tongsheng to resolve the assistance problems in the first two levels. We finally received a firmware version with fixes according to our guidelines. The first two levels have started working as expected. The assistance is as smooth and responsive as on the third level. Maximum power is limited to 30% and 50% of that of the third level.

The first assistance level:

TSDZ8 first level assistance update

The second assistance level:

TSDZ8 second level assistance update

Those are the maximum amperage values recorded for the first two assistance levels. More importantly, the torque sensor finally works correctly on the first two levels. There is scaling based on the power applied to the cranks. Without the firmware update, the assistance does not work properly on these levels.

Example power readings from the second level (power from the battery must be decreased by the efficiency of the motor ~73%):

TSDZ8 second level assistance low

TSDZ8 second level assistance low

We offer a firmware update service for TSDZ8 750W 48V motors if anyone is interested in flashing the motor running an older version. 

Riding impressions:

Because we had problems with the first two levels of assistance, we spent most of our riding time in the third assistance level. 

Our test motor was running the firmware version with a fixed walk assist error released by the manufacturer in January (TSZ8_7_1.6_.hex). 

Firmware update (04.03.2024)

The updated TSDZ8 firmware version we received from the manufacturer fixes the first two assistance level issues. 

The torque sensor works very well. The motor assistance kicks in right from the very start. The motor starts assisting seamlessly and smoothly adding power as the cadence increases.

Importantly, the assistance is smooth and gentle from the very start. You can ride smoothly even with a minimum speed. Doing 180 turns without any fear that the assistance will kick in unpredictably (like it does in motors without the torque sensor). 

When accelerating hard, the motor increases power substantially along with a rapid increase in cadence. The feel is similar to the "Boost" feature in the TSDZ2 open-source firmware. It works surprisingly well and runs smoothly. The difference is that here the motor is putting out power up to a very high cadence. Unlike TSDZ2, there's no "hitting wall" effect when the TSDZ2 motors almost stop assisting at around 80-85 cadence. TSDZ8 still assists at a cadence of 120-130. When you add to this the increased power of the motor, you have a truly great riding experience. This works well both when we want to accelerate suddenly, and in technical terrain where we need to rapidly generate more power.

The quality of the assistance provided by the TSDZ8 is comparable to the TSDZ2 with open source firmware (OSF) in hybrid mode (that's what we tested the TSDZ2 in). Only a direct comparison shows that the TSDZ8 has a marginally higher "overrun". The motor still runs for a fraction of a second after the assistance turns off. The difference is there, but we had to pay close attention to even notice it.

To sum it up, the assistance in the TSDZ8 works surprisingly well and seamlessly. There is a huge difference when compared to the original firmware in the TSDZ2. The feel is comparable to the TSDZ2 with open-source firmware (OSF). The biggest problem is the badly scaled first two assistance levels in the old firmware versions. 

There's also an improvement in the cranks' design. The left crank has an offset, while the right crank is straight. As a result, the Q-factor is better than in the TSDZ2, so the offset of the feet relative to the center of the bike frame is smaller. 

TSDZ8 korby bez odsunięcia offsetu


The TSDZ8 is quieter than the TSDZ2. It makes a slightly "whistling" sound, but its intensity does not increase significantly with motor speed. The TSDZ2 at higher rpm seems to be very loud compared to the TSDZ8.


The motor supports the same displays that originally worked with TSDZ2. The controller connector is 8PIN. This allows for connecting compatible displays such as VLCD5. For 6PIN displays, you need a 1T4 wire harness with a 6PIN connector for the display. 

Our TSDZ8 motor kits come with the 860C displays. Visual aspects and display size aside, the main advantage is the ability to check voltage readings on the display. The VLCD5 does not have this feature.

TSDZ8 860C display

The displays have Bluetooth connectivity. The display manufacturer has an I-Bike+ app, which lets you check the display data on your smartphone. 

TSDZ8 860C display I-Bike+ app

Build quality:

You can check our Tongsheng TSDZ8 750W 48V teardown, disassembly article to see what the motor components look like on the inside. 

The motor survived our tests. It is used daily on a commuter bike which is also used for offroad riding. It already has several hundred kilometers of heavy use on the odometer. It was taken apart and then put back together. It spent a few hours on the trainer, partially running at maximum power. It was tested off-road. On climbs and technical single tracks. It completed several longer rides. It also had an accidental "bath" in the river. During one of the tests, riding through river-flooded fields, the water reached the motor level. Three times. The water was above the bottom bracket level covering the whole motor. The motor still managed to ride a dozen kilometers more to the destination without any problems. There was no sign of water ingress.

So far there are no signs of wear on the motor. It seems to be solid, but only long-term testing can indicate which components may be prone to failing.

Low voltage protection:

The TSDZ8 has a built-in mechanism to reduce power at low battery voltage. From our tests, it appears that at about 43V, power starts to be reduced. Despite giving the max throttle, maximum power decreases as the voltage drops. The screenshot from the BMS shows 700W instead of 1100W. To some extent, this protects the battery from a voltage drop below the cutoff limit. With a 52V battery, this effect will not occur at all, because the nominal voltage and the cutoff voltage are set higher.

TSDZ8 low voltage power decrease mechanism

Errors and motor failures reported by the customers: 

One of the customers reported a problem with his TSDZ8 motor. The "err 18" error showed up on the EKD01 display. We attempted to provide some help, but the manual for the display has no such error listed. The manufacturer stated that they do not sell motors with this display. The motor was most likely purchased on Aliexpress. This is the version with a gear sensor connector and EKD01 display. It is advisable to be aware of what source you buy the motor from. After-sales support and service are of great importance.

TSDZ8 error 18

Customers reported a problem with the walk-assist mode. The manufacturer released new firmware that fixed this problem. After flashing the new version, the issue does not occur anymore. It is worth paying attention to whether the motor you are buying has the latest version of the firmware. Programming kits are not freely available and there will be a problem with flashing the TSDZ8 motor bought from a third party that does not have the latest firmware.

TSDZ8 walk assist issue


The motor is sold with a heavy steel 44T chainring as standard. The offset is about 16mm. The chainring is not narrow wide.

The manufacturer and customers report that there are compatibility problems with some chains.


We have designed our TSDZ8 130BCD adapter compatible with narrow wide 130BCD chainrings. The offset is 11mm. We also have a compatible aluminum chainring cover.

TSDZ8 adapter 130BCD


The chainline with the original 44T steel chainring (16mm offset) looks fine when the motor is installed without any spacers on the bottom bracket. 

TSDZ8 chainline 44T

Motor installation and bike frame compatibility:

The motor is compatible with BSA standard 68-73mm bottom brackets. The manufacturer has provided an A4 TSDZ8 fitting guide template to check the fitment on your bike frame.

The main gear is slightly smaller in diameter than in TSDZ2 or ToSeven motors. On newer bikes, this will make a difference, as the boost standard leaves less space for the chainring and main gear housing. A bike's rear triangle can cause clearance issues so it is important to have a more compact main gear housing. 

Porównanie wielkości obudowy przekładni TSDZ

TSDZ8 wymiary


The TSDZ8 motor is larger and heavier than the TSDZ2. The motor itself weighs about 4.6kg. Together with the original chainring, cranks, and bolts, the weight will be closer to 6kg.

TSDZ8 weight


The TSDZ8 48V 750W motor has positively surprised us. The improvements over the TSDZ2 (TSDZ2B) are noticeable. There is clear inspiration from Bafang's BBS motor designs.


+ Seamless assistance (after firmware update - older firmware versions have problems with levels 1 and 2)

+ Assistance up to a very high cadence (120-130 rpm)

+ Improved cooling compared to TSDZ2. The motor is in direct contact with the motor housing and dissipates heat very well. It does not overheat at nominal, rated power

+ Better efficiency than TSDZ2 running the original firmware

+ Noise. Compared to the TSDZ2, it is much quieter

+ More power. You can feel the difference in power compared to TSDZ2. The TSDZ8 can be used with throttle. It has enough power for that application. For example, it is not recommended to use throttle with the ToSeven DM02

+ Better build quality than TSDZ2. Many of the design flaws of TSDZ2 motors have been improved in TSDZ8

+ The motor works with 48V and 52V batteries out of the box


- The lack of configuration settings that are available in the TSDZ2 open-source firmware (OSF)

- Problems with the first two levels of assistance (on older firmware versions)

- Problems with the walk-assist mode (on older firmware versions)

- Weight 4.6kg (bare motor without cranks, chainring and bolts)

- Heavy 44T steel chainring without narrow wide teeth that reportedly has compatibility issues with some chains