This page is about cables, throttles, displays, speed sensors and shift sensors.
Cabling a conversion is very difficult process because it can either look very poor or it can look perfect. The goal, of course, is to attach the cables in such a manner that is conducive to the safety and practicality of the bike...with an eye to esthetics. There are some fundamentals to keep in mind when attaching the cables of the Bafang motor, battery, brakes, display, throttle, shift sensor, and speed sensor, and these fundamentals must be slavishly followed. For example, never give in to the temptation to run a cable in a place that may comprise the safety of the bike for sake of ease of installation. As I said, cabling is a difficult process. I have seen what happens when a builder places the power cord on the drive side of the bike (because it was easier and faster) and when the chain fell off to the inside of the chainring it cut the cord and shorted out both the battery and the motor. Sometimes, when cabling a full suspension bike, I have to route my cables in a manner that will move with chainstay and thus may not look as clean as our hard tail conversions. When this happens, I explain why we chose to route our cables in a less than appealing fashion. The secret to routing electric cables on a bike is to look at the bike, find the natural lines of the bike and follow what already has been established. Design engineers have created these bikes with esthetics and function in mind. Therefore, proper cabling follows the path already created by the original designers of the bike.
This is the Bafng T-4 harness. It is called a T-4 because it has four leads. The green lead is for the display. Take a piece of tape and mork this so you can find it when needed. The two yellow female leads are for the two brake levers with the motor cutoff. The yellow make lead is for the optional throttle. One of the yellow female leads can be used for a gear sensor if your motor came without the gear sensor cable at the base of the motor. All of these cable are Hilgo connections. Hilgo connectors are very water resistant. This harness can be found with one lead (T-1), two leads (T-2), and three leads (T-3). Or, you can simply remove any lead not in use. Be careful you do not remove a lead you might need or may need in the future.
The large end is the part that connects to the motor. When connecting, be sure to push the two cables together firmly. It can be difficult, especially in cold weather. Before connecting, take a good look at the bike and make sure that the routing is going to be correct. Sometimes this cable will go over the battery cable and sometimes it will go under the battery cable. Also, at times you will run this cable on the bottom of the top tube, other times it will be on the bottom of the downtube. If it is a full suspension bike you might have to run it up the seat tube. Study the bike! This is one cable that is very difficult to shorten as the wires are so tiny it becomes nearly impossible to solder then together.
Cabling your bike can look terrible, or it can look as neat as anything made by the large electric bike manufacturers. A few years back I received an email from someone who saw one of my builds online and said, "Your cable work looks like crap." I replied, "I know it does and that is why I lay asleep at night trying to find ways that are better." To get better at cabling study what others have done. Everytime we get a bike in our shop from a electric bike company we study everything about that bike. One time we were looking at a bike that was built by the largest bike company in Canada and discovered they were using a glue gun and a clothes pin (wooden) as a motor stop against the bike frame.
Bafang cables are long. They have to be in order to accommodate a large range of bicycles. On some of our build we need to use extensions because the bike is larger than the cables can reach. Small and xtrasmall bikes have their own challenge in that there is far too much cable. You have to get creative. It is never a good idea to just wrap the cables around the seatpost. We have seen this many times and it always looks terrible. Anyone can cable a large frame but it takes patience, creativity, and imagination to somehow make the cables look like they were custom made for your bike.
This the power cable from the battery to the motor. We see this type of wiring on bikes often that come to our shop for repair. Note that the power cable is laying next to the chainring. If the chain falls off on the inside of the chainring it will cut the power line. Never run any cable next to the chainring. The power cable is the one cable that can be shortened. They are either #8 or #10 gauge wires that are large enough to strip, splice, and solder. Or, you can use connectors like the Anderson Powerpole, or other types of crimp connectors.
This is how we connect the battery to the motor. We cut both the wires from the battery and the wires from the motor. We install Anderson Powerpole connecters and secure them with a locking pin. We use heat shrink to seal the connections.
NOTE: Before cutting the wires from the battery make sure the battery IS NOT connected to the wires!!! Always cut one wire at a time.
NOTE: Bafang motors have a capacitor which stores power. Alway assume the capacitor is charged. Cut one wire at a time and do not cross positive (red) with negative (black) wires.
This is the Bafang DPC965 five button display. It also comes in a three button model. As with all displays there are a few things to be careful of. First, be careful you do not over tighten the small screws as they can (will) crack the attachment points. Secondly, these are tiny bolts and locknuts. They are very easy to drop and even easier to lose. Your display will come with one nut and bolt for the display control, and two nuts and bolts for the display. If you lose one of these parts then that is a trip to the hardware store.
The C965 is a monochrome display. These displays are also available in color.
This is the full color DPC 14 display. A full color display is around $75 more than a DPC 965 display. Our favorite is the monochrome DPC 965. One of the major problems with display is one has a tendency to take their eyes off the road to read the information on the display. On a power assisted bike this is a very dangerous habit. To take your eyes off the road while traveling 28 miles an hour you will cover a distance of 41 feet! A lot of obstacles can appear in 41 feet. The more glamorous the display that is loaded with data the greater the likelihood of one spending too long to gaze at the display.
This is a very important display and we always carry them in stock. Notice the controls on this display are on the display itself. Other displays have the controls on a short cable. If your bike has super wide bars, or high riser bars, this is the display you will need, along with a display extension cable. If you do use this display you will have to take your hand off the bar in able to reach the display control. Riding a electric bike with one hand while trying to change the power settings is a very bad idea. You always want to be able to adjust your power levels with your thumb and that means the display control cannot be half way down the bars.
This is one of the newest type of displays for electric bikes. It is also the smallest. The size makes it difficult to read by a quick glance but its popularity rests in its stealthy appearance. Some do not like the look of a large screen located on the front of their bike. on of the features of this displays is that it allows one to set all of the parameters of the controller in a Bafang motor. While this seems like a great idea, the problem is that unless you know how to set the parameters correctly you are likely to burn up the controller. Unless you know what you are doing, it is very easy to take a high performance motor and cause it to run poorly, or damage the motor by exceeding its design parameters.
While it is possible to use no display at all it is not practical. There are tutorials online that show how to cut and splice the wiring of the display in order to bypass it. The Bafang motor works in conjunction with the display. If the display becomes disconnected, or is damaged, the motor will not run. One of the things a display does is alert us when there is a failure in the system. It has a number of codes it will display telling us where the problem is and them we will know how to approach a fix. If the display is bypassed then we lose this important feature.
This little sensor is used as a motor cut off switch for those who have hydraulic brakes. First, the small black sensor is to be glued near the brake lever. Then, a small magnet is glued or Ziptied to the brake lever. When the lever is pulled the magnet moves away from the sensor shutting off the motor. Our confidence in this product is very low as the magnet or the sensor often falls off while riding. Also, some hydraulic brake systems are shaped in such a way there is no practical way to attach both magnet and sensor in such a fashion that they would functioned. What to do? You can convert the front wheel to a mechanical disc brake, or you can order a hydraulic brake system with a built in motor cutoff.
This small device is called a shift or gear sensor. Originally it was a product developed and sold by a company in the Czech Republic. Today, this product is widely sold by other companies on Amazon, eBay, AliBaba and AliExpress. If purchasing for your bike make sure the connecting end is compatible with your motor. The yellow connector, shown above, is a Hilgo connector used on a Bafang BBS02 and the BBSHD. Note; this part is not included in the Bafang electric bike motor kit. Most sellers of the Bafang motor kit believe this device is essential to the smooth operation of the Bafang motor but none of them include it in their motor kits. Makes you wonder how essential it is if it is not included in the kit. It is like selling a clock with no hands. If it is essential then do not sell the kit without one included. The point is that these little devices are not essential and are an option for those forget to stop pedaling between shifts.
Pretty simple mechanism. It has small three rollers that sit on the top and the bottom of the cable as it passes through the device. Any movement of the cable is detected and a signal is sent to the controller of the motor that says "off." Once the shift is complete a second signal is sent to the controller that says "on." This whole process takes less than a second. A second does not sound like a lot of time but under some circumstances a second is far too long. Once, on a climb I hit a sharp corner so I immediately downshifted. The gear sensor detected the shift and shut of power for a brief moment and that was not a time I wanted the motor to shut off for any amount of time. The bike almost stopped altogether as I lost my forward momentum. So, if one chooses to use a shift sensor they have to have a full understanding of how they work and what happens when they fail to work.
Good question. Nearly all sellers of the Bafang motor kit promote the use of the shift sensor and are happy to sell you one. It might be noted that the company that manufactures the Bafang mid drive motors do not sell shift sensors and never include them in their motor kits.
Some riders prefer a shift sensor while others do not. Sometimes, a rough road can trigger the shift sensor causing the motor to intermittently cut out. Those who ride aggressively in off road conditions might be better off without a shift sensor. If you decide to install a shift sensor make sure it is done in a manner that holds the sensor static. The sensor cannot move. It has to be held firmly in place in order for the cable to move freely. If the sensor moves then it will not work.
When riding a bike, one shifts from one gear to the next by while pedaling. That is not altogether true. Yes, you keep the pedals moving but you do not apply pressure. You may have heard people shifting while climbing a hill. The steeper the hill the louder the noise while shifting. NOTE: Noise does not mean damage. When shifting an electric bike, pause between shifts. In other words, every time you shift..stop pedaling, shift, then resume pedaling. When you stop pedaling the motor stops applying force and allows for smooth shifting. It is not just electric bikes that need this pause, it is all bike. Ease up on the pressure on the pedals and the bike will always shift smoother. On non powered bikes you can get away with pedaling though shifts and many riders do so without a thought. However, under the power of a750 watt motor shifting errors are amplified. Practice shifting while easing up on the pedal stroke and you will notice the difference. Shifting while going uphill is harder to do but is necessary in order to prolong the life of the drivetrain of your bike.
First, you need to snip off the end cap of the shift cable at the rear derailleur. This has to be done in order to pull the cable through the cable housing. Then you release the anchor bolt. Go to the front of the bike and pull the shift cable free from the shifter. Slowly pull the cable until you think it is far enough in order to cut the cable housing without cutting the cable. Cut the cable housing about in the middle of the chainstay. Take a sharp pick and round out the area where your cutting tool compressed the strands. Put an housing cap on both ends of the cable housing where it was cut. Thread the cable through the housing, into the shift sensor, and through the derailleur and reattach at the anchor bolt. Often the cable will be too short and you will have to remove some of the housing. In addition, cables often fray and cannot pass through the shift sensor. When this happens you will need to use a new cable, so have one on hand. If your bike has a twist shifter, or internal shift cable this can be a very difficult and time consuming task. It is highly advised to install the shift sensor prior to installing the motor.
First and foremost it effects the quality of shifting by introducing considerable drag. While downshifting, this drag is not noticeable because you physically move the chain on the derailleur by the strength of your hand. It is when the derailleur moves back down the cassette that one has a problem. What moves the derailleur down is the derailleur spring. Some expensive derailleurs have a very powerful spring and can overcome the drag. Most derailleurs have a spring that is designed to work without any drag on the system. The drag imposed by the shift sensor is just enough to mimic a crimped, fouled cable housing, or incorrect routing of the cable. Everything will still work fine but it will not be a smooth shifting pattern coming down the cassette with a shift sensor installed.
The speed sensor is a small device (pictured above) that is attached either to the front fork or the chainstay of the bicycle frame. Its function is to measure the number of revolutions per minute providing an estimate of the speed of the bike. The Bafang motor will not operate correctly unless this device is set up correctly. Note: The small magnet in the picture above is a magnet that needs a special tool. You will need a Torx security head tool. You can use any spoke magnet that will fit your spokes. If you have blade spokes, or extra large spokes, this magnet will not fit. Sometimes, we will file out the center of this magnet and use an industrial glue gun to attach the magnet. It does not matter what wheel you use for this sensor. Sometimes, the spokes on a back wheel are too far for the sensor to reach and if that is the case we attach the sensor to the front wheel.
We always install the speed sensor on the non drive side. That leaves the drive side available for a shift sensor. In installing this sensor the goal is to install it without telescoping the sensor to reach the magnet. If you telescope the sensor you increase the chances of the owner snapping the sensor off when the wheel is removed. Rather than telescoping the sensor we place a piece of hard rubber between the sensor and the frame which will decrease the distance to the sensor. We use rubber because when we tighten the zip ties it will make for a better connection.
When bikes come into our shop that have been converted by others the first thing we correct is the shift sensor. Almost always we find loose magnets and sensors.
You will use Zipties to attach the speed sensor to the chainstay. Above, is a picture of a Ziptie puller. You need this tool to get the Ziptie as tight as possible. When attaching the Ziptie use the largest and strongest possible (see picture on left) as you do not want the sensor to move once it is in place. Small Zipties may look nicer but you cannot pull them tight enough without them snapping. NOTE: Only use Zipties with a UV rating for outdoor use.
We dedicate Zipties to hold the sensor in place. In other words the two Zipties holding the speed sensor hold nothe else. That insures a tight connection that prevents the sensor from moving. Too often we see other cables bundled up against the sensor. This is done to save money on Zipties I suppose. We do not bundle anything to the two Zipties holding the speed sensor.
Here the magnet is attached to a spoke approximately 2mm or 1/8 inch from the sensor. These magnets take a special torx drive with a security tip. They are not very expensive so it is not much of a problem but will require a trip to the hardware store. Attaching a magnet to a spoke seems like a simple tack but sometimes it is very problematic. For example, blade spokes. For awhile blade spokes were very popular and we still see them in our shop. These stock Bafang magnets will not fit a blade spoke. You can order magnets that will fit a bladed spoke and those will work fine. Or, you can file out the middle of the Bafang spoke and attach it to the spoke using a glue gun. For this type of application we use a low melt, industrial glue gun. We do not use a hobby glue gun.
Two things regarding the set screw: First, this tiny screw is very easy to lose and difficult to fine once lost. Fortunately, Bafang often packs two of these screws with each kit. Second, do not forget to us this screw. Seems obvious, but when bikes come to our shop others have built we often find this screw missing (yes, we always check) and if it is not used the sensor will work itself loose, come into contact with the magnet and snap off. Once a speed sensor snaps off the display stops working in a normal fashion. Everything will continue to work on the bike and the motor will still run but the information on the display will be incorrect. Remember, try not to telescope the sensor, use the largest Zipties, dedicate the Zipties to the sensor only, remember the set screw, and...well that is about it.
The speed sensor is an important part of the Bafang motor system so it has to be installed correctly. Sometimes it will be a simple task and other times we spend hours trying to figure out how to attach it to a bike where the spokes are far from any potential attachment points. Sometimes we have the opposite problem: The spokes are too close to the attachment points and no matter how it is set up the spoke magnet hits the sensor. Every day we come up with new and innovative ways of solving these difficult problems and I know you also will do the same.
What is a green button and what is it used for? A green button is a Bafang motor kill switch. It is an aftermarket part and sometimes it will come with a image of a horn on the green button. The reason for the horn image is because the same button is used for a hown. On the inside, if the wires are attached left to right it is a horn. If the wires are attached right to left, it is a motor kill switch.
This little button has an odd history.
This is a Wuxing hrn button used as a Bafang kill switch. This button is used as a motor kill switch in lieu of a shift sensor. The idea is to push this button, which shuts off the motor, shift gears, then release the motor. Personally, I think this is not necessary with either the BBS02 750 or the BBSHD 1000 watt motor. When shifting always pause, let the motor calm down on its own, make your shift, and off you go. However, these buttons are very inexpensive and if you think it might be helpful then give it a go. The only downside is the green button does not open like the display and display control so you have to remove everything on the bar in order to slide it on.
On every bike with hydraulic brakes we install the Wuxing Green Button to be used as an emergency kill switch. If a bike has mechanical brakes we use the Bafang motor cut off brake levers. A electric motor needs some kind of shut off switch. For example, if you crashed and the throttle was jammed up against an obstruction and the motor is still engaged it is necessary there be some way to stop the motor. That is what we use the Green Button for, an emergency shut off. If your bike has hydraulic brakes consider installing one of these buttons.
Throttles can be problematic. People like throttles on their bikes so we install a lot of them but we do so in a way that helps prevent accidental activation. A throttle turns on the full power of the motor and therefore to accidentally deploy the throttle can have unpleasant consequences. it happens more often than one thinks. It goes like this; someone standing next to the bike, out of curiosity says, "What does this little lever do?" You can imagine what happens next. When installing the throttle do not put it to close to the brake lever. Most people like to put the throttle as close to the brake lever as possible as it makes it easier to reach. Put the throttle a bit distant from the brake lever or put it on the other side of the display control. If the throttle is invertanly deployed and there is no one sitting on the bike, it can rear up and run over whatever or whoever is in front of the bike. That said, throttles can be fun and they are requested by around 80% of our clients.
This is the throttle that comes with the Bafang kit. This is an adequate throttle. It works well, and we have yet to see one fail. When you install the throttle there is one very important matter to consider and to ignore this is to do so at your own peril. Brake levers are attached to the bars in a variety of ways using hex bolts. Sometimes, these hex bolts can come into contact with the throttle lever causing it to stick in the wide open position!!! Make sure the throttle lever is nowhere near a brake lever bolt, or anything else for that matter. If the thumb lever is a fraction away from anything that can obstruct it, eventually the throttle may slip and become a dangerous liability to the rider.
Also, tighten the throttle down as tight as possible so it does not slide over and come into contact with an obstruction. Throttles can be dangerous not only to the rider but anyone who might be in the path of a electric bike whose throttle has been inadvertently activated or stuck in a wide open position.
In my opinion this is the best throttle for a number of reasons. For one, it is less likely to get caught on something and become stuck. The design of this throttle makes it fit on the bars much better. The thumb paddle is oriented differently than the Bafang stock throttle making it less likely to be activated by a bystander. This throttle fits on the bars much better than the stock throttle. It looks better, once installed, because of the way it fits. The lever is under the bars and the band is much thinner. Because the band (the part that circles the bars) is thinner it allows you to scoot the controls closer together. If they are closer together they are easier to reach.
Hands down, this is a much better throttle than the stock throttle and is a worthwhile upgrade. Cost is around $25.
These things are terrible and we do not install them on any bike we build. First, they are difficult to install. If you are going to use the half twist throttle you might as well purchase three pairs as you are sure to ruin the first two trying to install them. Also, once installed they do not work that well and fail much more often than a thumb throttle.
These full twist throttles are equally as bad as the half twist throttles. Perhaps there are some quality aftermarket throttles for the Bafang system but if there are we have yet to see them. As for now, we do not recommend half twist or full twist throttles.
Any bike equipped with the Bafang BBS02 750 watt motor does need a throttle as it has the power to launch from a standstill without effort. Also, once you begin to peddle you will have all the power at your fingertips that a throttle would provide. In my opinion, when weighed against all the negatives of a throttle against any benefits, it might be best to forgo the throttle.