CHOOSING A DIY CONVERSION MID-DRIVE MOTOR

We will compare the most popular mid-drive motors for DIY conversions
  • BBS02 vs. BBSHD 
  • BBS02 vs. TSDZ2
  • Bafang BBSHD or BBS02 vs. CYC X1 Pro or Stealth

 

Bafang BBS02 vs. BBSHD
Bafang DIY ebike conversion mid-drive motors are some of the most popular motors on the planet, and with good reason.  They are solid, reliable, powerful, and the quietest mid-drive motors we have found. They are quieter than geared hub motors and the big brand mid-drive motors like Bosch, Yamaha, and Brose. And are almost as silent as direct-drive hub motors.  If silent running is high on your list, then Bafang mid-drive motors are a clear winner.
 
  
Bafang BBSHD 1000W

Bafang BBSHD 1000W


Bafang BBS02
Bafang makes the BBS01/02 motor in a 250-watt, 350-watt, and 500-watt mid-drive configuration, but at Electrify Bike Co., we only carry the BBS02 750-watt.  Why is that?  The 250-watt and 350-watt motors are primarily for countries with e-bike laws limiting the maximum watts to those wattages.  In the USA, the e-bike watt limit is 750 watts, so the BBS02 is perfect.  For some bikes, customers, and riding conditions, the 500-watt motor makes more sense. But the 500-watt motor is the same price as the 750-watt motor, and we can configure the 750-watt motor to be a 500-watt motor when it makes sense to do so. A 750-watt motor can become a 500-watt motor when 750 watts is too powerful for the bike or the rider. A 750-watt motor will also last longer when run at the lower wattage.

The BBS02 only comes in a single bottom bracket size.  It can fit in bottom brackets that are 68mm and 73mm wide.  It fits a standard threaded 68 or 73mm bottom bracket.  If you have a press-fit bottom bracket of this width, we have adapters that can convert your bottom bracket to the threaded standard so the BBS02 can fit.  If you have a wider bottom bracket, you will need to use either the Bafang BBSHD or CYC X1 Pro.

The BBS02 is our go-to motor for the majority of bikes and customers. Quiet and powerful, the BBS02 cranks out 120Nm of torque.  Compare that to most high-end factory e-bikes with mid-drive motors having torques topping out at 65Nm to 80Nm. It is affordable and fits almost all older bikes and newer bikes that don’t have a high-end wider bottom bracket.

Bafang BBSHD
The BBSHD is a 1000-watt beast of a motor.  It is about 3.5lbs heavier than the BBS02 and delivers a peak power of over 1500 watts. Although weighing in at about 13lbs, this motor is super silent and has a massive torque of 160Nm.  There are small cars with that same amount of torque.

When given its full range of power, this motor is strictly for off-road use where motorized vehicles are allowed.  However, it can be programmed to be street and bike trail legal if you want to use it everywhere and just like this motor’s ruggedness and reliability.  For those that want street-legal and full power, we also sell a unique display that can reprogram the motor for a street-legal, power-limited mode and an off-rode, full-power mode depending on where you are riding.  The display is the Eggrider V2.

In addition to the 68/73mm bottom bracket sizes that the BBS02 fits, the BBSHD also comes in a 100mm and 120mm BB width.  These are typically used exclusively on fat bikes.  The BBSHD is always an excellent choice for a fat bike because they are heavier and often used in sand, snow, or steep terrain.  However,  The 100mm also bridges the gap down to 83-92mm bottom brackets. These are popular BB widths for high-end mountain bikes.  To fit the BBSHD, these typically require press-fit adapters and 8-16mm of bottom bracket spacers, and these conversions are solid.  When possible, the spacers should go on the non-drive side to help equalize the Q-factor.  Exceptions are when some spacing is necessary on the drive side so that the “gear reduction housing” clears the right chain stay.

Bafang mid-drive motor issues
The BBS02 and BBSHD are a tried and proven but older design.  Their single-piece construction has simplified DIY conversions but has some limitations for modern high-end bikes.  Most newer mountain bikes have a downtube that extends out from the bottom bracket nearly horizontal before curving up to the headtube.  Bafang designed the BBS motors 6 to 8 years ago when almost all bikes’ downtube came straight down from the head-tube to the bottom bracket without curving horizontally.  This geometry allowed the motor to rotate up against the downtube when installing it to get good ground clearance.  When you put a Bafang BBS mid-drive motor on a newer, more modern mountain bike, it can’t rotate up, and as a result, it hangs down with less than optimal ground clearance and less than optimal appearance.  CYC Motors designed the new CYC X1 Pro and CYC X1 Stealth to eliminate this problem and to have excellent ground clearance and a sleek appearance on all frame types.

Carbon frames often cannot accommodate a Bafang mid-drive motor because the bottom bracket shell casing is too thick.  Bafang mid-drive motors have a 12mm clearance between the motor housing and the spindle.  Most carbon frames have a BB shell casing thicker than this, and the motor won’t slide into the bottom bracket.  The newer design of the CYC motors eliminates this problem.


Bafang mid-drive motors are cadence only, meaning that the motor knows when you are pedaling and how fast you are pedaling. But it doesn’t know how hard you are pedaling. It has 24 magnets to detect cadence, but it doesn’t have a torque sensor to detect your effort. Tong Sheng TSDZ2 and CYC Motors mid-drives have torque sensors.

Many Bafang users complain that it is more like a motorcycle than a bike. It’s no wonder they say this because Bafang configures these motors at the factory to have about 50% power in assist level one. That is attenuated by the speed % also set to 50% but that is still crazy.  When you start pedaling in level one, you have over 200 watts on a BBS02 and over 300 watts on a BBSHD.  That is close to the same power that factory e-bikes have on their highest level of assistance, typically 250-350 watts.  The Electrify Bike Co. secret sauce for Bafang includes programming each motor to start at around 100 watts and then increase linearly with each assist level to full power at the highest level.  This way, the Bafang mid-drive assists at a low enough level that it still feels natural despite not having a torque sensor. A low level of assistance makes it still feel like a bike, extends battery range, and lets you get as much exercise as you want.


BBS02 vs. BBSHD Summary
If you have a 68/73mm bottom bracket, then the chances are that the BBS02 will be what you want.  If you have a fat bike with a 100-120mm bottom bracket or a mountain bike with an 83-92mm bottom bracket, you will need the BBSHD.  If you are carrying lots of weight, have a cargo bike, a heavy cruiser, or just want all the torque you can get for steep terrain, you may also want to lean toward the BBSHD.  However, keep in mind that many people underestimate the BBS02 750-watt. They convince themselves they need the BBSHD but have never ridden the BBS02 to know just how powerful it is.  In our parking lot on flat terrain, we let customers ride bikes with each motor, and they often come back and say they couldn’t tell the difference between the BBS02 and the BBSHD.


Bafang mid-drives vs TSDZ2
Ok, let’s cut to the chase on this one right up front.  Both the BBS02 and the TSDZ2 are close together in price, and they are both mid-drive motors.  That’s about as far as their similarities go.  They each have their place, and choosing one over the other is simply a matter of what features you value the most.

Advantages of the TSDZ2 over the BBS02
Those drawn to the TSDZ2 usually wind up there by searching “torque sensing mid-drive motor.”  Until the CYC line of mid-drive motors came out, the TSDZ2 was the only game in town for torque sensing and is the primary advantage it has over the Bafang mid-drive motors.  With torque-sensing, the motor not only knows that you are pedaling, but it knows how hard you are pedaling and can respond accordingly.  It can feel very natural to have the ebike respond by magnifying your effort with motor power and not just put out a constant amount of power whenever you are pedaling as the Bafang motors do,

The TSDZ2 is also lighter than the BBS02.  If you are trying to respect a lightweight bike and keep your electric conversion’s weight to a minimum, the TSDZ2 will help.

The TSDZ2 comes in a coaster brake version.  If you have a coaster brake bike this is the only game in town.  There are no other motors either mid-drive or rear hub that can work with a coaster brake.  You could put a front hub motor on a coaster brake bike but front hubs have issues of their own.

One other advantage of the TSDZ2 is the Open Source Firmware (OSF) that is available for it.  This firmware replaces the factory firmware and provides extensive customization of the way the motor responds.  Those that like to fiddle and fine-tune the performance have an extensive array of options with this firmware.


Advantages of Bafang mid-drives over the TSDZ2
That said, the Bafang motors are both quieter and more powerful than the TSDZ2.  Some TSDZ2 motors are quieter than others but it is the luck of the draw.  You don't know beforehand if you will be lucky or not. But even the quieter TSDZ2 motors are not nearly as quiet as the BBS02 or even the BBSHD.
 
Bafang vs TSDZ2 plastic gear

If you compare the motor components of the BBS02 and the TSDZ2, it is striking how much beefier the BBS02 is. The more substantial BBS02 parts provide more power, better heat dissipation, and reliability.  All of which tilt toward the Bafang motors.


DIY Mid-drive Motor Feature Comparison Chart


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