We will compare the most popular mid-drive motors for DIY conversions
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 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.
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.
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
These guidelines and instructions assume you bought your battery with your motor or ebike and that its power and charge capacity is matched to your motor and charger, respectively.
If you are buying them separately, there is a lot more you need to know to ensure you have the right battery and don’t have a potentially dangerous combination. Ideally, your battery can deliver more power than your motor can use and charge faster than your charger can charge. With headroom for both, your battery will not be stressed, will be safer, and will last longer.
Li-ion is virtually maintenance-free, and the battery lasts the longest when operating between 30 and 80 percent of a full charge. Unlike other battery chemistries, Lithium-Ion has no memory and can be topped off whenever needed
When your battery is new
Apply a topping charge before use. For this first charge, you should charge your battery to 100% full. If you have time, leave it on the charger for about 12 hours to ensure at that all of the cells have an even charge. After that, you can charge it to 80 or 90% to prolong battery life if you have a smart charger, and then every few months or so after a deep discharge, do a full 12-hour topping charge to level the cells.
Basic ebike battery charging guidelines:
Storing your Li-ion ebike battery
The two most important things to be aware of when storing your battery are charge percent and temperature. To store your battery longer than a few weeks you should target its charge to between 40% to 70% of full. Never store your battery at 100% charge. This will reduce its overall life. Also, never store your battery below 40% charge because the battery will lose capacity over time. If it falls below its low voltage which is around 2.6-2.8 volts per cell, it can become permanently damaged and the cells may not take a charge after that.
When storing for long periods of time the voltage should be periodically checked and when needed, charged to above 50% This could be as frequent as every 3 to 6 months.
Keep your battery at a moderate temperature. It will last longer if you store Li-ion at a partial charge in a cool place. The worst combination is high 100% voltage and elevated temperature. For long-term storage (several months or more), store Li-ion at approximately 50 percent charge. Ensure that you don’t leave the battery for any length of time where temperatures can climb above 120 degrees Fahrenheit, such as in a closed car or building without climate control.
If the temperature drops below 32 degrees Fahrenheit (0°C), do not charge the battery, or damage may occur. Bring the battery indoors and let it warm up before charging it. It is ok to discharge your battery (ride your bike) when it is cold, but it will reduce your range. It will not, however, harm your battery or reduce its life. Conversely, do not charge if the temperature is above 120 degrees Fahrenheit or damage will also occur.
Li-Ion and safety
Lithium-Ion batteries can be a fire hazard. If you buy quality batteries with name-brand cells from a reputable source, this hazard is extremely minimal. However, if any of the cells in the battery become damaged from dropping or by exceeding charge/discharge limits this risk will go up. It is a good idea to not leave a charging battery completely unattended and you should not charge the battery in close proximity to flammable items. If there is visible damage to the cells from dropping or water ingress, the battery should be recycled and replaced.
Extending the life of your battery
The easiest way to extend your battery’s life is only to charge it to 80% or 90% when not riding it for a few days. Most rides won’t require anywhere near a full charge anyway. Doing this will extend the life of your battery by 2 or 3 times. If you know that you are going for a long ride and want to make sure you have all the power your battery can store, top it off to 100%. Doing so just before a ride will not lessen your battery’s life. To control the charge to shut off at 80% or 90%, you will need an “advanced” or “smart” charger with this feature. Most chargers that come with an ebike do not have this feature.
Suppose you are using a smart charger to extend your battery life by charging to 80% or 90%, in that case, after a deep discharge, you should still occasionally charge your battery to 100% to give your battery’s internal electronics (BMS) a chance to rebalance the cells to get the maximum capacity.
Placing a high drain on your battery will reduce its life. If your battery is rated at 40 amps continuous power, you shouldn’t necessarily run it at that power for long. If your battery becomes warm to the touch while using it, you may be drawing too much current for too long. The battery’s BMS rating may allow you to draw more current when needed, but you should be aware that you shouldn’t abuse it.
Don’t charge your battery too fast too many times. Just like electric cars that have fast-charging stations, you can charge your ebike fast as well. Electric car manufacturers warn not to use the fast charging station all the time, or it will reduce the life of the car’s battery. Unlike fast chargers for cars, most ebike fast chargers are well within your battery’s safe charge limits that won’t decrease its life.
For example, all of the battery cells Electrify Bike Co. uses in their batteries can take a charge of 1.5 amps without reducing battery life. Our most popular battery, the Super Shark, has 14 cells in series and 4 of those series in parallel. Four times 1.5 amps is six amps so a charger to charge at six amps without any decrease of battery life. Our fastest chargers are just four and five amps, which is only two-thirds of the safe charge level. Each cell also has a fast charge rating that is safe but will reduce the battery life if used frequently. This rating is around 2.5 amps per cell which would be 10 amps for a 4p battery.
The Electrify Bike Co. mini-cube batteries have two series of cells in parallel and can be fast-charged at five amps. Since our fast charger is four amps which is right between the fast charge rating of five amps and the standard charge rating of 3 amps, it will have a nominal impact on battery life. For maximum battery life of a mini-cube battery, you should use a two or three amp charger.
Charging with a “Smart Charger”
Smart Chargers can automatically stop charging at 80%, 90%, or 100% charge. This is selectable with a rotary switch on the end of the charger. Electrify Bike Company has Smart Chargers in 2 amp and 4 amp sizes for 36v, 48v, 52v, and 72v batteries. We also have Advanced Smart Chargers in these same voltages that have an additional rotary switch for selecting from 1 to 6 amps. The Advanced Smart Chargers also have an on/off switch and a display that shows volts and amps.
We recommend that the best way to use a smart charger is to charge to 90% after every ride so your bike is always ready to go. Then if you are going for an extra-long ride and want to make sure you have maximum battery range you can top it off to 100%. Topping your battery off to 100% just before a ride does not negatively impact your battery life.
Ebike Battery - Frequently Asked Questions
How should I prepare a new battery?
Apply a topping charge before use.
Should I charge my ebike after every ride?
If your battery is below 40% you should charge it. If you will not be riding for a few weeks, you should only charge it to 50 to 80% to maximize battery life.
Can you overcharge an electric bike battery?
Most ebike chargers and batteries have protection circuits that make it impossible to overcharge the battery. However, batteries should not be left on a charger for extended periods of time at 100% as this lowers the life of the battery.
How long does it take to charge an electric bike?
Ebike batteries normally take 3-6 hours to charge. If the battery is not fully discharged, this can be a lot less. A 2 amp charger will take twice as long to charge as a 4 amp charger.
Do electric bikes charge when you pedal?
No. This would be like pedaling a generator. Some motors can charge the battery when braking or going downhill, but this usually only adds less than 5% to the battery charge while adding 20% to the weight of the bike. It is often better to just get a bigger battery.
How often should I charge my ebike battery?
It depends on how far you rode your bike and how far you will ride your next time out. If you are only going for short rides, you may go a week or more between charges. It is better for the battery to not be topped off to 100% all the time.
Can you ride an electric bike in the rain?
Yes, the components are ok in light rain. The bike should not be left out in a downpour or on a car with water drenching it from the car’s wheels. Never submerge a motor, battery, or electronic components or wash or rinse with a pressure washer.
How long do batteries last on electric bikes?
Batteries typically last many years. If charged to 100% they can take 300 to 500 full charge cycles before the capacity is reduced to 85% of its original capacity. If you charge it twice a week that will be 3 to 5 years. However, you get more partial charges than full charges and when your 3-500 full charges are used up the battery still has 85% capacity. If you have a smart charger that can charge to 80/90/100% you can extend that life to 1000 to 2000 full charge cycles.
Can I charge my ebike battery overnight?
It is not recommended to charge your battery unattended. If you charge to 100% you should ride your ebike right away to maximize battery life.
How much does it cost to charge an electric bike battery?
A typical 500-900 watt-hour battery will cost 10-20 cents to charge. (Compare that to a tank of gas!)
Can I damage a battery with incorrect use?
Keep partially charged. A low charge can damage cells. Full charge reduces life. Extreme temperatures reduce life.
Do I need to always charge it full?
A partial charge is better than a full charge for longevity.
Can I disrupt the charge cycle?
A partial charge causes no harm.
Should I use up all battery energy before charging?
No. Deep discharging wears the battery down.
Do I have to worry about battery “memory”?
No, There is no memory with Lithium-Ion.
How do I calibrate or balance the cells with a “smart” battery?
Charge to 100%. Repeat every 1–3 months.
How do I store my battery?
Store in a cool place partially charged.
Does the battery heat up on charge?
No, it should stay cool or slightly warm. If it gets hotter, you are charging too fast or it may be damaged and can be dangerous.
How do I charge when cold?
Do not charge below freezing. If it is below 32 degrees Fahrenheit take it indoors to charge.
Can I charge at hot temperatures?
Do not charge above 120°F (50°C).