In this TSDZ2 vs BBS02 comparison I will offer my opinion on these mid drive electric bike conversion kits. Over the last couple of years I have installed more than a hundred Bafang mid drives, and more recently around twenty Tongsheng systems.
Both the Tongsheng TSDZ2 and the Bafang BBS02 are market leaders in mid-drive electric bike conversion kits, with the latter having a substantially larger slice of the pie.
The Bafang motor is well-established, and despite some ongoing reliability issues, still offers the most bang for your buck. A BBS02 750w will kick out close to 1500w with a 52v battery fitted. This will transform your humble bicycle into a high performance speed machine (but the 52v battery will compromise reliability). I always recommend sticking with a 48v battery, unless you are willing to shell out for replacement controllers.
The pedal assist system (PAS) on the Bafang motor acts like an on/off switch. As soon as the pedals rotate a few degrees, the motor kicks in. The pedal assist on all the Bafang BBS motors can be fine-tuned with controller programming and careful selection of the 9 available power levels.
With this method of pedal assist you just have to turn the pedals to get assistance, you don’t have to put a lot of effort in. It is possible to climb a 25% gradient in a low gear with the power level set to 9. All you will be doing is spinning the pedals, the motor will be doing most of the work!
The BBS02 has a lot of potential for fine-tuning. Being able to reprogram this motor is a real bonus.
It should be noted, that compared to a normal bike the Bafang is harder to pedal when the motor is switched off. This is not so much of an issue when cycling on the flat, but if you find yourself out of battery power, pedalling up a steep hill can be practically impossible.
The BBS02 has a lot of potential for fine-tuning. Being able to reprogram this motor is a real bonus, and in some cases necessary. In my experience, the factory pedal assist settings are not very good, in particular the way the pedal assist stops and starts. Thankfully these can be changed in a matter of minutes by connecting your motor to your laptop using a Bafang USB lead and this free open source software.
The TSDZ2 has been around for a while now, and early reliability issues seem to have been resolved. It is now a very viable alternative to the Bafang BBS02. And unlike the Bafang, Tonsheng specifically lists a 52v version.
The main difference between these two motors is the pedal assist. With the Tongsheng it is not a free ride. You are rewarded with more power only if you put the effort in.
The progressive surge of power you get in sport mode really does make you feel like the bionic man!
The Tongsheng uses torque sensing pedal assist. This gives you motor-assistance proportionate to how much force you are applying to the pedals. This makes for a very intuitive system right out-of-the-box.
Even using the 48v750w version, you still have to put some degree of effort into pedaling in order for the motor to work. I really like this, as it feels a like a Bosch motor on steroids!
The progressive surge of power you get in sport mode really does make you feel like the bionic man! The motor feels more like an extension to your own cycling abilities.
If you prefer to ride at a high pedalling cadence, it is worth noting that these motors do not produce any noticeable assistance above 90rpm. The initial burst of power fades quickly when these high cadences are reached, even though force is still being applied to the pedals.
With the motor switched off, the Tongsheng wins, hands down over the Bafang. Although there is some increased pedalling resistance, it is nowhere near as noticeable as on the BBS02.
If the BBS02 is the lazy man’s electric bike conversion kit, then the TSDZ2 is for people that don’t mind working up a bit of a sweat. Although the 500w and 750w versions are substantially quicker than their lower powered counterparts, you still have to put in some effort to get the motor working.
The only downside with the Tongsheng motor, is programming the controller. It is possible but it is not as straightforward as with the Bafang, also you are limited to only 4 different levels of assist versus the Bafang’s 9 levels.
Pro’s and Con’s
- Very responsive pedal assist
- 9 levels of pedal assist
- Good spare parts availability – click here for list of parts
- Well established brand
- Very powerful
- Some reliability issues still persist
- Pedalling resistance, when motor is switched off
- The motor may need periodic tightening
- More expensive than the Tongsheng
- Feels more like an electric motorcycle (not a bad thing, if that is what you are looking for)
- Stock controller settings are not very intuitive
- Intuitive torque sensing system
- Easier to pedal than the Bafang when the motor is switched off
- Lighter than the Bafang
- Can provide a ‘more natural’ cycling experience
- Very efficient motor / increased battery range
- Parts availability is good – click here for a parts list
- Great value
- A certain degree of pedalling effort is required to start the motor – this may not be suitable for everyone
- Programming is possible, but not as straightforward as the Bafang
- Only 4 levels of assistance
- The motor does not give any noticeable assistance at high pedalling cadences.
- The blue nylon primary gear can be prone to premature failure
- Although the torque sensor is generally reliable, it has been known to fail.
Both of these motors are excellent in their own way, but the choice really boils down to your own personal preferences.
If you want an enhanced cycling experience, with the motor feeling like an extension to your own ability, then the Tongsheng is definitely the way to go. If you have a medical condition that limits your ability to pedal hard, then the Bafang may be more suitable.
Either way, both of these motors are great fun. If I had to make a choice, based on my own personal experiences, then I would have to choose the Tongsheng over the Bafang. Unfortunately I have had a disproportionately high amount of controller failures with the BBS02, and my confidence in their long term reliability has been tarnished. To date I have had no major issues with any TSDZ2 I have installed.
If you are concerned about the current e-bike laws, it is worth remembering that both the BBS02 and 500w / 750w TSDZ2 are not road legal in the UK, EU or Australia. If you do choose to use them on the road you do so at your own risk and most importantly you need to consider the potential risk to others. Please read my guide to electric bike law here.
If you choose to go down this path, make sure at the very least you limit the top assisted speed to 25km/h (15mph) and ride sensibly. The consequences could be dire if you were to have an accident riding one of these on the road – RIDE SAFE!
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