Tongsheng TSDZ2 Mid Drive Motor E-bike Conversion Kit


Tongsheng TSDZ2 is a Chinese made motor engine that could power up almost all bicycles and turn into a functioning e-bike. It is easily mountable and has a wide fanbase worldwide. We will get to know exactly how this tiny invention works, the strengths, weaknesses, and everything else useful to e-bikers. We’ll also get to understand the firmware and other software-related properties. So, what are waiting for? Let’s get things started…

E-bikes and General Street rules

Before we get a little technical, I think it is better to understand just how safe it gets on the road with a motorized bike. The road code categorizes e-bikes as any motor-assisted bicycle, powered through the pedals with a maximum power not exceeding 250 W and distribution of engine use up to 25 km/hr. Keeping that in mind, having any motorized bike with powers exceeding 250 Watts should be driven in restricted areas or free zones not governed by the highway rules.

Torque Sensor Mechanism

So, Tongsheng’s TSDZ2 has torque sensors that measure the amount of force you put on the pedals and subsequently provide a multiple of that force from, Eco(2x) to Turbo(15x). Even in Turbo modes, you will still have to add some force to keep the e-bike going. Torque sensors are the more sophisticated type of PAS and work well for mild workout riding sessions.


Riding with a Torque Sensor (advantages and shortcomings)

Well, the most noticeable feeling when you step on a torque sensor e-bike is how the modulation of power affects your pedal assistance. You will hear e-bikers say that, when activated, TS models have a natural feel. In simpler terms, the torque’s level of power is proportional to the pedal’s push of the biker. It allows bikers to ride on tough terrains and eases riding experience on roads/ highways.

Another great benefit torque sensors provide is that they are quite counter-reactive and starts almost instantly. Consequently, it stops immediately you turn it off, although the developers at Tongsheng have a split second delay for safety purposes. The reactivity in torque sensors is great especially during an uphill ride. Imagine the sensor stopping in the middle of an inclination and refuses to start? That doesn’t sound good to me either.

The result of such advantages is more contained power consumption. Rather than just joyriding the e-bike, as with other types of PAS, the biker has to pedal faster in order to achieve more power. Both the torque sensor and the biker need to work hand in hand. Depending on how you take it, this could be an advantage or a disadvantage. For some reason, I think the torque sensor is great for a seamless workout plan without extra strain or sweat. However, it is still disadvantageous as you may burn yourself out trying to achieve higher power distribution: torque sensor will decrease its power as you reduce the number of revolutions while pedaling.

A closer look…

Once you remove the side cover, you will quickly notice a connection of several wires intertwined here and there. The three larger BGY (Blue, Green, and Yellow) wires are the motor phase wires (maximum, 18A). Other five smaller wires attached to the white plug operate as Hall sensors. The thin BGY wires trigger on/off signal to the sensor. The red and black Hall wires are negative and positive for the thin BGY wires.

All motors come in rather similar shapes and dimensions but they only differ in the amounts of output power. The power output relies on the type of battery charge installed on the motor. A 36V powered torque sensor produces a nominal output of 250/350W, while the 48V types have greater amounts of power that reach up to 500W and 750W respectively. Well, don’t be fooled by the massive powers that torque sensors have: they all have similar dimensions, and Tongsheng’s TSDZ2 is even as tiny.

The maximum torque of the motor depends on the power output. A 250W supply has a max torque of 30Nm whereas a 90Nm can hold up to 750W. Remember, Tongsheng does not give any connectors to the main control unit, so these figures are present. There are upcoming developers who managed to design firmware that allows you to tweak a few parameters allowing total control of your unit. Just be sure to consider your warranty void once you get your hands on the open source firmware.

Motor mechanisms and battery

Mounting the TSDZ2 is relatively easy and does not require a bicycle expert to install the motor. A 36V or 48V battery is available, which connect to the motor and connecting pins. You can place the battery either on one of the bottle holders or in bags hanging from the horizontal frame. Also, if you manage to hack into the control unit you can set the motor to work with 52V batteries as well.

You can choose of two main display types- either the standard VLCD-5 model or a smaller version such as XH18 model in the handlebar. Consumer reports also indicate that the motor system is waterproof and have rare cases of electric failure during rainy days.


A quick look at the display and you will notice running speed, total battery charge, mileage, and other minor parameters. You can choose from four power modes between, Turbo, Speed, Tour, and Eco. It is also possible to do a bit of presets. For instance, engaging and disengaging the lockout at 25 km/h (although I strongly disagree), input the number of kilometers in relation to the diameter of the wheel. Some models have a USB connection that is able to charge a smartphone or GPS.

Here is a definition cheat sheet of some functions:

Recommended units are placed in brackets()

dl – wheel diameter, 14-32 inch (26)

cc- the number of wheel magnets in speed sensor, 1-12 (1)

speed units- km/h or mile/h (km/h)

sd- speed limit 15-45km/h (25)

A- Power mode adjustment, 0-32 A (16)

M- Mode, Japan Europe (EUR)

25 km/h speed limit, on/off   (on)

General appearance and mechanics

Since the TSDZ2 comes separately with the bike, let’s analyze how our bikes would look like after mounting the motor kit. One thing is obvious is the wires are noticeable (from the handlebar) but the motor itself…hmmm, not so much. In fact, only one side view is the motor kit fully visible.

If you want a better outlook, we recommend that you try to place the batteries inside a small pouch at the lower frame rather than at the carrier. Putting at the back is also disadvantageous especially during steep climbs and off-road rides.

Riding on a Tongsheng TSDZ2 mounted bike

So how is the riding experience with TSDZ2? Keep reading.

Before we begin, it’s is better not to push the pedal when you want to turn on the display. The motor needs to reset the torque sensor properly to correctly start the engine thrust. In case you find your motor not thrusting properly, just switch it off and back on again.

Now as you start the engine, try not to go on the faster power modes, and push the pedals lightly for a smother “take off”. As soon as you start rolling, you will notice a constant buzz from the motor, which tells you the engine has started. Most people think that the noise increases with an increase in speed. However, it is barely noticeable at high speeds. The engine noise diffuses with wind and other external sounds like brakes etc.

Since the motor has a maximum cadence of 80/85 pedals per minute, on flat surfaces the motor assistance is barely felt, and your ride feels natural, even at higher speeds. Here, the engine’s performance is constant and rarely has any heat or power loss. In fact, you really do not have to reach top speeds to know how powerful this motor works. Even at fair speeds, the motor’s performance is fluid and you use very little effort while pedaling.

Tongsheng TSDZ2 vs Bafang BBS-HD 

Before we continue a little further, here is a table comparing the TSDZ2 and a similar motor kit from Bafang. Some of these differences will give you a hint of how the motor feels when turned on.

  Bafang BBS-HD Tongsheng TSDZ2
Advantages -Can be mounted in fat bikes

-Includes a programmable controller

-Efficiently fast

-Great value for money ($642 to $672)


-Great torque sensing system. Almost intuitive

-Easier to pedal when motor is switched off as compared to BBSHD

-Prolonged battery range

-Spare parts are easily available

-Great value for money (350W kits at $334-$384)

Disadvantages -Difficult to install especially while removing the bottom bracket

-Requires prolonged maintenance

-Additional power can burn out e-bike’s gear components

-Barely legal on the road

-Can reach high speeds, dangerous without protective gear


-Difficult to install for non-experienced bikers

-Torque sensing stops at high pedaling rpm

-Consumer report indicate unreliable during off road use

-Torque sensing assist can be tricky for first timers


Notable features -Has 9 power-assist levels

-Straightfoward programming module

-pedal assist is doesn’t require much pedaling

-Hard to ride on when motor switched off


-4 power-assist levels

-Complex programming module and modification needs open source firmware

-Pedal assist requires rider’s efforts

-Unnoticeable changes to pedaling when motor is switched off


Moving uphill is usually one of the biggest tests bike enthusiasts like to perform with such motorized bikes. Well, the TSDZ2 has responsive mechanisms that allow you to glide uphill with considerable pedaling effort. However, riding on inclined surfaces can have grave consequences on your gear. If let’s say you are in the middle of an uphill climb and the motor turns off (Not so good? Right?) The correct approach to starting the sensor is to switch it on with little force on the pedals. If you turn on with the same force on the pedal as you would in a manual bike, the force sensor reads this data and the engine torque will peak at maximum peak power and can really damage the engine parts.

In such a case, the blue reduction gear is usually the first to be affected and can slip or melt resulting in funny noises in the engine. Although there are other gears (like Teflon gear) within the motor system, Tongsheng designated the blue reduction gear as the weak point in case of such emergencies. The other steel gears are somewhat more expensive to replace. Once you damage the blue reduction gear, the most suitable replacement is a bronze gear, which is noisier than normal stock gears. You can also do a little research online and maybe you can find a similar replacement gear.


– Quick and easy to assemble parts

– Easy to use for all commute types or workouts

– Lesser energy consumption as compared to mileage covered

– Spare parts are easily accessible



– Needs a bit of learning time otherwise, there is a risk of mechanical damage

– The manufacturer does not provide access to the control unit (no software included)

Here is the video of how to install TSDZ2



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Electronic information engineering. Electric Bike Lover.

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