While I was having a blast riding my e-bike, I was also dropping my chain at least once on every ride. After my 1st hundred miles of riding this problem became very annoying. The chain drop was caused by the chainline. Ideally, the front chain ring and the rear sprockets should be parallel to the centerline of the bike and angled as little as possible, see illustration below. But, when the chainline is mismatched there is a sideward stress on the chain that causes the chain to drop off the front chainring.
It seems a bit short sighted for Bafang to ignore this design issue on a bicycle conversion kit. They must be aware of the problem. A google search on “Bafang Chainline” will illustrate countless examples of the problem as well as offer numerous solutions to this issue. Simple design changes like placing the Bafang Motor Controller on the non-drive side of the motor or adding chainring spaces to better position the chainring would have greatly reduced the chainline angle.
My solution didn’t address the chainline but it did eliminate the chain drops. Since I already had a front derailleur, I simply reinstalled it and adjusted the limiter screws to perfectly align the front derailleur to act as a chain guard to keep the chain from falling off the chainring. While I do get some chain rub on the front derailleur in my lowest gears, the problem is solved at no additional cost.
I started out very conservatively on level 1. The Bafang has assist levels ranging from 1-9 with each level providing more assist. Levels 1-2 feel more like my natural cycling speed of about 15 miles per hour but the effort is like having a substantial tail wind at my back. At the higher levels, I found myself cruising up to the maximum speed of 28 miles per hour with little effort.
I quickly headed for the nearest steep hill, increased the assist level and zipped up it. I was having a blast! I took several Strava KOM without knowing it. Feeling a little guilty afterwards about breaking a lot of the Strava records around town, I found that I could record my rides as e-bike rides on Strava without taking anyone’s hard earned KOM. While I wonder how many are actually earned honestly, mine, if I ever get a KOM, will be honest.
Needless to say, I know I am going to log a lot of miles on my new e-bike.
The last step to completing the Bafang conversion kit was mounting the speed and shift sensors and wiring everything together. The speed sensor is basically the same as any other wired bicycle speedometer. A magnet is mounted on a rear spoke and the sensor is mounted on the frame. The control panel is then programmed for the proper wheel size to calculate the speed each time the magnet passes the sensor.
While I was tempted to bypass the shift sensor to save a few dollars, I’m glad I didn’t. Since you must be pedaling to shift the gears and the motor is engaged when the pedals are turning, the motor would be engaged while shifting. The problem is that the motor provides far more torque than the derailleur, cassette and chain can handle while shifting and would damage these parts without the sensor. The shift sensor disengages the motor when you shift for normal torque on the parts when shifting.
Wiring it all together was much simpler than I expected. The Bafang wiring harness and components are all color coded for plug and play wiring. It is just matter of matching the colored plugs, lining up the pins and sticking them together. It was as simple as that and I was ready to ride!
Perhaps the hardest part of converting a road bike into an electric bike with the Bafang kit is the cockpit. Space is very limited on my handlebars because I have four brake levers (drop and cross top levers). So, finding space to mount the BAFANG controls along with my Garmin GPS/bike computer was challenging.
Making matters worse, the Bafang controls are designed for mountain bikes with straight handlebars that have a 31.8mm mounting diameter and taper to 22.2mm at the bar end. Because the on/off switch, pedal assist level selector and throttle are meant to be mounted towards the end of mountain bike bars with 22.2mm diameter mounting clamps, the Bafang controls will not fit the considerably wider road bike drop handlebars.
This seems a bit short sighted by Bafang to ignore the road bike market. However, there is a work around that works well. I purchased a handlebar extender that mounts to a 31.8mm diameter drop handlebar and has a 22.2mm diameter extension bar. With the on/off, pedal assist level selector and throttle mounted on the extension bar, both are within finger reach while both my hands are firmly planted on the tops of my handlebars.
Getting a tight fit on the handlebar extension can be challenging. I had to make shims for the handlebar extenders to ensure a tight fit on the handlebars. Shims can be made by cutting strips out of an old inner tube or aluminum beverage can. Caution, do not overtighten the clamps as the clamps are made out of an aluminum alloy and will strip the threads if over tightened.
Mounting the BAFANG battery was a bit tricky. The battery is designed for mounting on the down tube using the water bottle cage mount. However, my 48V 17.5Ah Jumbo Shark Pack Battery is so large that I would have to give up both water bottle cages.
Instead, I mounted the battery on a rear rack. Although they make rear racks especially for e-bike batteries, my battery is so large that I couldn’t find an e-bike specific rack the battery would fit on. As a result, I had to repurpose an old touring rack for the job and make my own mounts for the battery.
While I like the battery on the rear rack there are two drawbacks to carrying the battery on a rear rack. First, it puts the battery weight (approx. 9 lbs.) high on the bike. And second, it places the weight directly over the rear axle. Ideally you want the weight lower and centered with a more even weight distribution on the bike for better handling. Nevertheless, carrying a battery on a rack is not uncommon and I will ride it this way for a while to see how I like it.
Mounting the BAFANG motor is easy. The whole unit simply slides into the bottom bracket shell and is fastened into place with the provided hardware. Here again, you will need a special bottom bracket tool for this job. I would recommend purchasing the tool directly from BAFANG with the motor. It cost about $20.
A word of caution! Pay attention to the torque on the bolts mounting on the motor. The motor case is aluminum and can easily be stripped if over tightened.
Next, I installed the chain ring, crank arms and pedals. Take care to make sure you mount the crank arms on the correct sides. While they look identical, there is a left and right arm. If you get this step wrong, like I did, you will need a crank puller to get them back off. So, take your time and check the markings on crank arms before installing them.
Anyone handy with tools can do a Bafang electric bike conversion in a few hours. I started by removing the front derailleur, crankset and bottom bracket on my bicycle.
The front derailleur is no longer necessary and the crankset and bottom bracket are replaced with the BAFANG motor and cranks. A crank puller and bottom bracket tool are needed for their removal. And if your chain doesn’t have a master link then a chain tool will also be needed to remove the front derailleur.
Here are the parts that I removed with the tools I used. However, there are different types of cranks and bottom brackets. So the tools you need may be different. If you don’t have the tools needed consider having your local bike shop do this step for you. If you are a DIYer like me the tools will cost about $50 and can be found on Park Tool’s website at https://www.parktool.com/ along with detailed help on how these jobs are done.
The Bafang 750W BBS02 mid drive motor kit includes all the hardware needed to convert most mountain or recreational bikes with flat handlebars into an electric bike. However, in my case, I was converting an old 1997 Cannondale road bike with Shimano RSX 3×7 indexed shifter and integrated brake levers. As a result, the Bafang mechanical levers provided in the kit wouldn’t work for me.
The Bafang levers have built in Ebrakes that cut the power to the motor when the brakes are engaged. Initially I felt this feature was not necessary since the motor only provides power when the rider is pedaling and automatically cuts the power when the rider stops pedaling. This seemed unnecessary since I felt it was counterintuitive to pedal and break at the same time. However, on my first test ride without Ebrakes I quickly realized that on slow tight turns I did pedal and brake the same time to maintain the proper speed in the turn and it was not a time good time for the motor to kick in the power. Clearly, this was a safety feature that I didn’t want to give up.
Fortunately, with a little research I found Minshine MS-BK-1R inline brake sensors that plugged and played with my Shimano integrated shifter and brake levers and the Bafang Motor.
As I’ve said earlier, I haven’t always been a fan of electric bikes (see http://cycleacrossamerica.com/2018/11/29/e-bike-slackers/). But now that I am a septuagenarian and still love to get outside and ride my bike, electric bikes are looking more attractive to me. Unfortunately, electric bikes can be very costly ranging in price from about a thousand dollars to over ten thousand dollars. In addition, specifications can be very confusing with some retailers omitting important details from their advertisements (more on that subject to follow in later posts).
Not wanting to make an expensive mistake with my first e-bike, I decided to build an e-bike using a Bafang electric bike conversion kit. In that way, if I decided that I wanted an electric road bike I could use it on my road bike. But, if I later felt that I would rather have an electric mountain bike I could easily transfer the motor and battery to my mountain bike.
As a result, I decided on a Bafang 750W BBS02 Mid Drive Motor and Battery kit I found online at https://www.bafangusadirect.com/bafang-750w-bbs02-mid-drive-motor-and-battery-p/60.htm. Although I never heard of Bafang before, I found that it is a leading manufacturer of e-bike drive systems in Asia. While Bafang offers a larger 1000 Watt motor, I chose the 750 watt motor since electric bikes with motors over 750 watts are not legal on US roadways or allowed on federal trails.
It is clear that American’s have been slow to adopt e-bikes. Perhaps due to confusion over the wide variety of e-bikes on the market and what they are and what they are not. See Regulations of E-Bikes in North America sponsored by the National Institute for Transportation and Communities (NITC)
E-bike user and future users need to petition state legislatures and local governments now for permission to operate pedal-assisted bicycles legally on roadways and paths. We need to make it our job to help legislatures and local governments understand the difference between pedal-assisted and throttle-assisted bicycles. And to explain why pedal-assisted bicycle should be allowed on trails and in cycling events.
These changes will help to accommodate aging Americans who might otherwise not be able to continue to cycle and achieve the physical benefits similar to conventional bicycles despite the electric power assist.