TSDZ2B first drive - hard work - do I need OSF

[cimh]

First post here. I am a long time cyclist, After hitting 70 a year ago I started using a bafang 250w 37V hub drive gravel bike and have loved it often getting 80-100 miles from my small battery. I had a spare bike so decided to fit a TSDZ2B 37V 250w as I read people say mid drives are more efficient on hills so I thought lets try it. Quite puzzled to find that it is so much harder than my hub drive. I live in devon so plenty of hills. With the bafung rear hub drive I climb nearly all of them easily on level 1 or 2. Most of the time I dont use the motor. With the Tongshen levels 1-3 seem almost no extra power. I have to use level 4 or 5 to climb hills that were easy on level 1 with the hub drive. I can feel the torque sensor kicking in but it needs too much peddle pressure from me.

My questions are:
1. Does this feel right or am i expecting too much from the drive?
2. Do I need to switch to OSF? I wonder whether its hybrid mode would suit me more?
3. If that's the case I wonder why they make the drive to hard to use OOTB?

just to say the bafung hub drive also comes with a torque sensor

 

[E-HP]

My questions are:
1. Does this feel right or am i expecting too much from the drive?
2. Do I need to switch to OSF? I wonder whether its hybrid mode would suit me more?
3. If that's the case I wonder why they make the drive to hard to use OOTB?

1. The motor could likely deliver what you expect if level 4/5 can deliver enough power, when tuned to do so.
2. No, you could just ride it as is, or invest in the hardware, and time, to flash the OSF firmware and adjust it to suit you. It’s just another decision regarding what you want and what you’re willing to spend, with the risk that you still might not be happy.
3. Because people will pay for it. The stock firmware as well as the broken bottom bracket axle issues are well known, so just part of an informed/uninformed decision. They just don’t put that stuff in the advertisement.

I bought the Tsdz8 thinking tripling the power would be enough to outperform even a well tuned tsdz2b, without having to invest in the hardware to flash it. Well it sucked out of the box. There was no level where it didn’t feel tiring to ride, because of how it multiplied the pedal input. Level 5 had power, but I’d still feel tired from it. I spent a bunch on the interface (different hardware than for the tsdz2b) and flashed it with the latest non OSF firmware and it was night and day.
Looking more into the issue, I found it was well known, even in the short time the motor was out. I probably glossed over it if I did see a post about it (that sometimes happens if I’m leaning toward buying something). Sucks, because I might have waited for the tsdz16 if I knew the total cost of making my Tsdz8 purchase tolerable.

You might want to consider adding a torque sensor to your hub drive bike if it already performs well on the hills.

 

[farina]

I can feel the torque sensor kicking in but it needs too much peddle pressure from me.

Due to how the torque sensor initializes itself on startup, it's important to not be putting any pressure on the pedals when switching on. Maybe you should try leaving your feet off the pedals when turning on to see if that makes a difference. Otherwise, it seems
something is very wrong with your machine. On my own TSDZ2, the bike will zip right up hills with only a light push on the pedals, when in the highest assist levels.

 

[cimh]

On my own TSDZ2, the bike will zip right up hills with only a light push on the pedals, when in the highest assist levels.

Thank you. Is yours 250w /37V or higher? That might make a difference. I make sure I am not touching the pedals on switch on.

 

[cimh]

There was no level where it didn’t feel tiring to ride, because of how it multiplied the pedal input. Level 5 had power, but I’d still feel tired from it. I spent a bunch on the interface (different hardware than for the tsdz2b) and flashed it with the latest non OSF firmware and it was night and day.

Thank you, that sounds v similar to what I am experiencing. Presumably when you say night and day you mean it got better not worse? Provided my EKD01 display works I might try OSF. Do you recall what settings fixed it for you?

 

[E-HP]

Thank you, that sounds v similar to what I am experiencing. Presumably when you say night and day you mean it got better not worse?

]
It was way better.

Provided my EKD01 display works I might try OSF. Do you recall what settings fixed it for you?

Again, I have the Tsdz8, not the tsdz2b. There’s a 140 page thread on OSF for the Tsdz2/tsdz2b that’s still active where you can get better advice. My point is that how the motor responds to pedal pressure makes a big difference in how the assist ‘feels’, regardless of how much power the motor is capable of.
You will need to look at the OSF thread to see if the ekd01 is supported.

 

[docw009]

I had the same frustration with my TSDZ2 after owning hub motors, plus a BBS02 mid drive, for years, No perception of assist at all, unless in turbo. I bought the program adapter and set up my PC. OSF worked for me. Later, I set up a second TSDZ2B for my wife, but that's in cadence mode for EZ pedalling, We use the clunky VLDC5's.

I have the current limit to 14A or 15A. My wattmeter has seen my bike peak around 13A. I adjusted the assist levels so my bike felt right when pedalling it. Average speed when I ride with my wife is 12 mh. We must like them, as both bikes are coming up on 5000 miles. We don't have much hills, but the few hills I;ve seen haven't been an issue,

Last summer, I reinstalled the original firmware on my bike for a re-trial. Nope, it still sucks.

 

[cimh]

I have the current limit to 14A or 15A. My wattmeter has seen my bike peak around 13A. I adjusted the assist levels so my bike felt right when pedalling it. Average speed when I ride with my wife is 12 mh. We must like them, as both bikes are coming up on 5000 miles. We don't have much hills, but the few hills I;ve seen haven't been an issue,

Thankyou, That is really good to know as I was a little frustrated after my first run. It is strange that some of us struggle with the stock firmware, But great that people have written alternatives and made the freely available. I have ordered the st-link and will flash the OSF. What assist mode are you using? I think the hybrid set up will be the one I will try which is i think a mix of cadance and torque.

 

[docw009]

I found hybrid mode felt best in the original 1.C.2 release. I would use therecent 1.C.6.4 and newer releases for running hybrid mode. The earlier ones didn't have good hybrid response. You can check in the super big OSF thread for info on the EKD01. I believe the displays supplied for TSDZ2B have the right firmware to work.

 

[cimh]

You can check in the super big OSF thread for info on the EKD01.

Looking forward to trying it out. The Java Configurator allows you to select the EKD01 display which is good news.

 

[E-HP]

I found hybrid mode felt best in the original 1.C.2 release. I would use therecent 1.C.6.4 and newer releases for running hybrid mode. The earlier ones didn't have good hybrid response. You can check in the super big OSF thread for info on the EKD01. I believe the displays supplied for TSDZ2B have the right firmware to work.

Just out of curiosity, what does good hybrid response mean? Is hybrid the use of both torque sensing and cadence?

 

[docw009]

Just out of curiosity, what does good hybrid response mean? Is hybrid the use of both torque sensing and cadence?

Until you asked, I didn't know how any of these modes worked. I chose Hybrid by testing and riding. It felt the strongest,

From Google AI,
Here is its description of the four modes:

• 1. Power Assist Mode
  • Description: Assistance is proportional to the power delivered by the rider, which is calculated as Torque X Cadence
    
    
  • Behavior: The motor acts as a multiplier of your effort. If you pedal harder or faster (high RPM), you get more assist. It is generally smoother and feels more consistent at higher cadences compared to pure torque mode.
  • Best For: Commuting, long distances, and efficient riding where you want to maintain a constant pace.
• 2. Torque Assist Mode
  • Description: Assistance is proportional solely to the torque (pressure) applied to the pedals, regardless of how fast you are turning them.
  • Behavior: The harder you mash the pedals, the more power the motor delivers instantly. It feels very natural, similar to a regular bike but with stronger legs.
  • Best For: Technical riding, climbing steep hills from a standstill, and low-cadence riding.
• 3. Hybrid Assist Mode
  • Description: This mode merges the advantages of both torque and power modes by comparing the calculated assist levels for both and choosing the higher value.
  • Behavior: It combines the brute force of torque mode at low cadences with the smooth, high-speed power of power mode at high cadences.
  • Best For: All-around riding, offering versatility for both steep climbs and fast, flat sections.
• 4. eMTB Assist Mode
  • Description: A progressive mode that automatically varies the assist level based on the force applied to the pedals, simulating switching between different assist levels (e.g., eco to turbo) without manual input.
  • Behavior: It is often called an "automatic" or "enhanced torque" mode. It provides high torque at low RPM for climbing, and adapts to technical terrain (roots/rocks) by allowing for quick bursts of power or "ratcheting".
  • Best For: Technical mountain biking and unpredictable terrain, reducing the need to change assist levels manually.

Summary Table of OSF Assist Types

• Torque: Pressure-based.
• Power: Effort-based (Torque
  
  Cadence).
• Hybrid: Highest of Torque or Power.
• eMTB: Progressive, automated Torque

 

[cimh]

A lot of pressure was needed to overcome friction to move the pedals with the motor off. (This seems to be quite a variable finding among users) So I removed the chain ring using the 6 small bolts. It has a ring (red on the image) that slots into a groove (green) on the motor which was filled with thick heavy grease. Cleaning this out and replacing with a lighter oil made a massive difference. I guess this is to stop water getting in and oil getting out? I am a fair weather rider but will need to keep an eye on this.

BTW it is very hard to move the chairing backwards (or to push the bike backwards) is this normal?

 

[docw009]

Yes, a TSDZ2B can be very stiff and I guess it's all about how the cover gaskets are greased. I did nothing with my wife's bike, and it did loosen up with time.

 

[E-HP]

Until you asked, I didn't know how any of these modes worked. I chose Hybrid by testing and riding. It felt the strongest,

From Google AI,
Here is its description of the four modes:

• 1. Power Assist Mode
  • Description: Assistance is proportional to the power delivered by the rider, which is calculated as Torque X Cadence
    
    
  • Behavior: The motor acts as a multiplier of your effort. If you pedal harder or faster (high RPM), you get more assist. It is generally smoother and feels more consistent at higher cadences compared to pure torque mode.
  • Best For: Commuting, long distances, and efficient riding where you want to maintain a constant pace.
• 2. Torque Assist Mode
  • Description: Assistance is proportional solely to the torque (pressure) applied to the pedals, regardless of how fast you are turning them.
  • Behavior: The harder you mash the pedals, the more power the motor delivers instantly. It feels very natural, similar to a regular bike but with stronger legs.
  • Best For: Technical riding, climbing steep hills from a standstill, and low-cadence riding.
• 3. Hybrid Assist Mode
  • Description: This mode merges the advantages of both torque and power modes by comparing the calculated assist levels for both and choosing the higher value.
  • Behavior: It combines the brute force of torque mode at low cadences with the smooth, high-speed power of power mode at high cadences.
  • Best For: All-around riding, offering versatility for both steep climbs and fast, flat sections.
• 4. eMTB Assist Mode
  • Description: A progressive mode that automatically varies the assist level based on the force applied to the pedals, simulating switching between different assist levels (e.g., eco to turbo) without manual input.
  • Behavior: It is often called an "automatic" or "enhanced torque" mode. It provides high torque at low RPM for climbing, and adapts to technical terrain (roots/rocks) by allowing for quick bursts of power or "ratcheting".
  • Best For: Technical mountain biking and unpredictable terrain, reducing the need to change assist levels manually.

Summary Table of OSF Assist Types

• Torque: Pressure-based.
• Power: Effort-based (Torque
  View attachment 386087
  Cadence).
• Hybrid: Highest of Torque or Power.
• eMTB: Progressive, automated Torque

Wow, that's great info, thanks! Sounds like with hybrid, when you're pushing hard up a hill or when accelerating, it's going to by multiplying the pressure on the pedals. But when you're just cruising along at speed, when there's less pressure on the pedals, it uses cadence, and you can just cruise along comfortably with less effort.

 

[docw009]

Could be, but then again Google AI could be making it all up.

 

[cimh]

So degreasing the seal between the chainring and the motor and flashing the hybrid mode of the OSF to my TSDZ2B has made the bike really great. As you say it is night and day. Congrats to the OSF designers. Also to Aliexpress for the TS-link clone with the plug to fit the speed sensor cable for just £9 including tax and flight. Just 6 days from order to delivery.

The EXD01 display is very happy. Level 1 is more than I need so I will reflash with different parameters. Thank you all your help

 

[cimh]

This is a puzzle. I flashed the standard 36V settings a few days back but as I said level 1 was too strong. So today I reset all the levels lower and reflashed. Weird, Level 1 (eco) is significantly stronger than Level 2 (tour) or even Level 3. But my settings suggest that it should be the weakest (as you can see from my screenshot). I am a bit puzzled. I have set the display to my EKD01 and I am using hybrid mode start up. Level 1 should only have 1/2 the assist of level 2 but it has more? why?

Any ideas? Perhaps I don't understand the hybrid mode? The display uses 5 levels not 4 but I have set the 5th level to occur after turbo at a level of 130.

I guess could try just power rather than hybrid as power presumably uses a combination of cadence and torque anyway?

 

[rivers1]

Any ideas?

I suggest you set the Assist level 5 (%) to BEFORE ECO not AFTER TURBO. I had the same problem and BEFORE ECO fixed it. I use Power mode.

 

[cimh]

I suggest you set the Assist level 5 (%) to BEFORE ECO not AFTER TURBO. I had the same problem and BEFORE ECO fixed it. I use Power mode.

Yes thank you very much! Switching to Power and placing Level 5 before ECO solves it. I now have 5 smooth graded assist levels. The configurator manual suggests that it should be after TURBO with my EKD01:-

15 – Assist levels 5 (%)Setting the fifth assistance level for displays that support it.
- DISABLED, for displays with 4 levels.
- BEFORE ECO: if the fifth level position is before ECO (example DZ41).
- AFTER TURBO: if the fifth level position is after TURBO (example EKD01).