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In this Tongsheng TSDZ2 review, I’ll go over the pros and cons of this mid-drive e-bike conversion kit, based on my personal experience installing over 30 of these motors. It’s a great alternative to the Bafang, but as with all things electric, there’s the positives and negatives to consider.
- Very efficient
- Torque-sensing pedal assist
- Smooth performance
- Plug and play installation
- Good value for money
- Limited clearance between motor and bottom bracket
- Only compatible with 68-73mm threaded bottom bracket shells (not for pressfit)
- Blue nylon gear can fail prematurely
- Ingress of water – not very waterproof
- Torque-sensor can prematurely fail / cause problems
Tongsheng have been manufacturing plug and play mid-drive electric bike conversion kits for a few years now, and although not as popular as the Bafang mid drive conversion kits, Tongsheng are steadily increasing in popularity Earlier versions did have some reliability issues, but as with the Bafang, a lot of these seemed to have been ironed out now.
I have personally installed approximately thirty of these kits on to various bikes, ranging from low-step commuter bikes through to full-suspension mountain bikes.
The main criteria for installation is similar to the Bafang mid-drive, the Tongsheng TSDZ2 will fit any standard threaded bottom bracket which is 68mm-73mm wide, with an inside diameter of approximately 33.5mm.
It must be noted that these kits are not intended to be installed on bikes that use a pressed-fit bottom bracket as the BB shell dimensions would not be compatible with the motor shaft.
There can be a way around this if a special shim and mounting plate are machined by a professional engineer. It’s important that the shim is machined in an eccentric fashion so there is more clearance at the bottom. The reason for this, is there’s very little clearance between the motor housing and shaft.
Some pressfit bottom brackets are wider that 68mm-73mm, and if this is the case I would personally find a more suitable donor bike.
If your bike has an eccentric bottom bracket as fitted to tandems and bikes with internally geared hubs like the Shimano Nexus, installation is still possible, but may be problematic.
What’s included in the TSDZ2 conversion kit?
- The motor unit with integrated controller
- LCD Display – VLCD5 / XH18 / VLCD6
- Wiring loom
- Inner and outer lock-nuts
- Chainring 42T
- Speed sensor and wheel magnet
- A bag of various Allen bolts and screws
- Installation tool / spanner
Is the Tongsheng TSDZ2 legal?
This depends on your local laws. In the EU and UK, the 250w version with speed limited to 25km/h (15.5mph) would be legal to use on public roads. But, anything rated to more than 250w continuous power would not be legal to use on public roads. For more information read my article on electric bike law.
The installation of this motor is the same as with the Bafang Mid Drive. One of the really useful things about this kit, is unlike the Bafang kit, the Tongsheng kit comes with an installation spanner. If you are looking for a nice easy conversion to do yourself, but you have little or no experience with bicycle mechanics or using tools, I would not recommend this kit. I will write a separate post detailing the installation process with photos, but the installation will need to be carried out by someone who is fairly competent. Removing the bottom bracket can be a right pain, and you will require a lot of patience!
The installation video below shows the installation process, although it looks like they loosened the bottom bracket beforehand!
These motors have an internal torque sensor, and give assistance proportionate to the amount of force applied to the pedals (much like the Bosch system) . The upshot of this is, that you will need to make a certain degree of effort in order for the motor to work, unlike the Bafang system, which will give assistance as soon as the pedals are rotated.
These motors can be reprogrammed using this OpenSource firmware / embedded software but you will need to purchase a KT-LCD3 display. It is not as straightforward as programming a Bafang, but if you are willing to have a go, you can really fine-tune this motor to suit your particular needs.
It should also be noted that unlike the 48v Bafang motor, you cannot use a 52v battery with the 48v version of the Tongsheng. There are some suppliers selling a 52v version, but these are not recommended or endorsed by Tongsheng.
It should be noted that Tongsheng do not specifically manufacture a 52v TSDZ2, and that all the motor kits sold as 52v have modified firmware.
Like the Bafang, this motor works through a series of gears, and drives the rear wheel directly through a single front chainring. The benefit of this is the motor is using the bike’s gear ratios for maximum efficiency and torque. Also, like the Bafang motor, gear selection is important when pulling away or hill climbing.
How Reliable is the Tongsheng TSDZ2?
I have supplied and installed quite a few Tongsheng TSDZ2 motors and to date, and I have only had one issue reported, and this was on a bike being used for serious off-road riding.
- Although I haven’t personally had any issues with the Tongsheng, they can and do occur from time to time.
- The torque sensor has been known to fail – although this seems rare and a replacement is not overly expensive.
- Controller failure is also much rarer now than it was a few years ago, a replacement controller is much cheaper than a Bafang controller.
- The blue nylon reduction gear can be prone to premature wear, although this seems to hinge on how hard the bike is being ridden and is unlikely to be a problem on commuter and leisure bike.
- The ‘Sprag clutch’ or one way bearing has also been known to fail occasionally.
- Because of the way the power is delivered there doesn’t appear to be much of an increased risk of wear and tear on the bike chain and gear components.
The general feel is one of an enhanced cycling experience, you still have to put in an effort but it makes you feel like you have bionic legs, which is great fun!
Riding a Tongsheng powered Electric Bike
The first installation I did using a Tongsheng motor was on a Voodoo hardtail mountain bike, and I must say I was pleasantly surprised. The 250w motor is very quiet and smooth, and you have up to 4 levels of pedal assist to choose from – ECO / TOUR / SPEED / TURBO.
The torque sensing pedal assist works really well, and having ridden Bosch e-bikes, I would say the power delivery is very similar. The general feel is one of an enhanced cycling experience, you still have to put in an effort but it makes you feel like you have bionic legs, which is great fun!
Another big plus point is that unlike the Bafang motor, the pedalling resistance when the motor is switched off is barely noticeable, although I have been reliably informed that this can vary from motor to motor. Some users report significant resistance with the motor off. With the latest 2022 version (TSDZ2B) a new dual clutch design has all but eliminated pedalling resistance (with e-assist off).
As with the Bafang you will be limited to a single chainring, but Tongsheng offer a 42T as standard, which is much better gearing than the 44T minimum offered by Bafang. The TSDZ2 will also take a standard 110BCD chainring.
As this bike uses a torque sensing system, brakes with cut-off sensors are not required, reducing the need for more untidy external wires.
Another important consideration is the Q-factor – this is the distance between the pedal attachment points on the crank arms, when measured parallel to the bottom bracket axle. On the TSDZ2 the Q-factor is quite wide at 210mm – if this is a problem, it can be easily solved by fitting a pair off standard Bafang BBS or Shimano Steps FC-E6000 cranks arms which should reduce the above figure by 28mm.
This motor is also 30% lighter than the Bafang equivalent, and the overall look is a little more discreet – below is a photo of an Orange full suspension mountain bike that a customer converted. He also owns a Haibike and actually prefers the Tongsheng conversion!
Tongsheng TSDZ2B updated version
Update 6/9/2022 – The Tongsheng TSDZ2B(latest version) has a dual clutch design that greatly reduces motor resistance when pedalling unassisted. Other improvements have been made in the manufacturing process to improve reliability, although I don’t have the exact details on the areas improved at this time.
As with the Bafang, the Tongsheng will not be for everyone. Installation can be challenging and the motor may need periodic maintenance. It is nonetheless an excellent option, and the end result will be a bike that looks more like a factory produced e-bike.
The torque sensing system may not suit everyone, as you will still need to put a fair amount of effort in for the pedal assist to work. But for me personally, I loved the way it provides assistance. My only real complaint, is that I generally ride my bike at a higher cadence of between 80-100rpm, and this motor does not provide any assistance beyond 90rpm.
The TSDZ2 is also incredibly efficient if used wisely. I recently had 120 mile range from a 36v13ah battery, however I was only using ECO and TOUR mode on the hills -total elevation gain over that distance was 11000ft.
This motor is also a little cheaper than the Bafang, making it excellent value for money. Read my Bafang vs Tongsheng comparison.
If you are comfortable with your ability to install it, and you have an appropriate donor bike, then as long as you can live with some of the compromises, this is an excellent electric bike conversion option and an excellent alternative to the Bafang. There is also a good supply of spare parts available.
Where can I buy the Tongsheng TSDZ2
The Tongsheng is a very popular e-bike conversion kit and is available from various online retailers in multiple countries. Prices vary depending on where you live, but I’ve always found Aliexpress to be the cheapest. If you’re concerned about potential problems and want the easy returns route, then I’d be inclined to buy from Amazon or eBay as these platforms make the returns process very straightforward.
|Amazon (various locales)|
|Banggood (EU Shipping)|
How does the TSDZ2 fair against the Bafang mid-drive? Check out my Tongsheng vs Bafang comparison.
Thanks for reading. If you have any questions relating to the Tongsheng motor, please feel free to leave a comment below.