Bafang BBS02 Build on Schwinn Road Bike

[RayGo]

Following is my build of a Schwinn Searcher 1 hybrid/road bike with a Bafang BBS02 500w 36v mid-drive system. The build process was fairly easy thanks to all the helpful info from posters on the various threads here on this forum. So a big thanks to all those who went before me and posted on this forum. This build process will describe what I went through. It is a bit long but it pretty much sums up all the pages of posts regarding the Bafang mid-drive system.

I currently have an e-bike that was built for me back in 2004 by ZVO-Bikes. It is a Specialized Comp hardtail mountain bike with a 500w 36v chain-driven mid-drive motor with a custom NiMH battery setup. It has a twist throttle and no Pedal Assistance System.


About 2 years ago, the NiMH battery finally died and I found this forum to help build my own 12s 36v 20ah LiFePO4 battery using A123 cells. The bike and battery have been working great but I wanted a new lighter, faster, and quieter bike and hopefully more efficient for more distance. I want to be able to do the 100 mile century rides with my bike club. The Schwinn has 700cc x 1.5in road tires and 9 rear gears while the Specialized has 26in x 1.75in hybrid tires, 34T front chain ring and 8 rear gears. The ZVO X-Power motor is also very noisy, making a loud whinnying sound and takes up the entire center frame of the bike.

I was debating between the 48v or 36v BBS02 units and finally decided to go with the 36v mid-drive since I already had a battery I could share with it. I also had a chance to test ride a 750w 48v BBS02 unit at San Diego Electric Bike Company. That test ride was “scary” fun. That bike could pop wheelies with no problem and accelerated to over 40kph very quickly. It has much more power and speed than I need since I plan to use the new bike on paved roads on leisurely paced rides. I am more interested in distance than speed.

So I decided to get the Bafang 500w 36v unit, but was hesitant about buying it directly from a seller in China. I considered using a US based seller (sdelectricbike.com, lectriccycle.com or hi-powercycles.com) even with their higher prices in case of warranty problems and the ability to choose various optional hardware and have the controller settings customized. Then I came across the posters on this forum highly recommending Paul at em3ev in Hong Kong. Paul could customize your Bafang order, provided good product support and had a good reputation for quality products. His prices were much less than the US dealers even after adding in the cost of overseas shipping. I was all set to order from Paul in early November when Alibaba ran a special 11/11 one day sale. BTN (Back to Nature) offered the unit at $355.30 plus $83.08 shipping minus a $10 Alibaba discount for a total of $428.08. I could not resist the sale price and got lucky with the purchase. The unit arrived here well packaged and in good condition on Nov. 25th in southern California.




After unpacking all the parts, I found I was missing the 5 screws that hold the chain cover to the chain wheel and the spoke magnet for the speed sensor. The 5 screws were no problem but the local bike shops here did not just sell the spoke magnet. I contacted BTN using their on-line chat service and they quickly agreed to give me a Paypal credit of $10 to cover the cost of buying a speedmeter with magnet on e-bay. I was able to get a speedmeter on e-bay from a CA company in 3 days which worked out better than waiting on the part from China.

I have since completed installation of the BBS02 unit on my bike and everything seems to be working fine, so I am more than happy with my purchase from BTN. However, as I will discuss in more detail later, if you plan to program the controller yourself, then you can take a chance with a direct purchase from China. I would also recommend using Alibaba and/or Paypal in case of any problems. If you don’t want to mess with programming the unit, than I would recommend you use em3ev.com or other US companies for their custom programming and options. I did not like the stock controller settings at all. I also got the stock brake levers which are useless since I have hydraulic brakes. I also got a left thumb throttle which I managed to fit on the right side of the handlebar but I would have preferred a right thumb throttle. More on accessories later.

 

[RayGo]

So while I was waiting on the delivery of the BBS02 unit, I viewed the installation videos on california-ebike.com and the Czech girl at https://www.youtube.com/watch?v=Ia8lpz5J1pI. As I said, the installation was fairly easy. I purchased a crank extractor and bottom bracket tool from JensonUSA on sale for about $15. Removal of the cranks and bottom bracket went smoothly. However, I had a hard time fitting the BBS02 unit due to the height of the cable guide for the rear derailleur. The height caused the cable to deflect and rub on the motor housing which probably explains why they have a plastic piece installed there. If I turned the unit so the cable would not rub on the motor housing, the unit would then crush the cable guide and change the angle of the cable. I had to run back to the local bike shop and buy a “low profile” plastic cable guide which only cost $3.25 but required some modifying with a rotary tool.

The Schwinn has a 68mm bottom bracket and the BBS02 fit nicely after solving the cable guide issue. The chain also lines up nicely between the front chain wheel and the rear cogs. Finally, I got to install the M33 lock ring and the outer locking cover. I used a hammer and slotted screwdriver since I did not have a spanner wrench for the M33 nut and then used a strap wrench for the outer cover. I have since found a tool on e-bay for $6.36 that works with both lock rings.

I finished up by running the cables for the battery, speedmeter and display. I installed the display control buttons on the left side and the thumb throttle on the right side which is a bit of a stretch for my thumb. I also removed the front derailleur and shifter. I then installed a rear cargo rack, dual leg kickstand and mirror. Then it was finally time for a test ride even though I knew that I would get the Error Code 21 due to the missing spoke magnet.

That’s when I found out how “bad” the stock controller settings are. The error code allowed me to pick one PAS setting before it locked up the controller. The stock PAS 0 does nothing, meaning no pedal assistance and no throttle control. I then powered off and back on to reset the controller. Then I chose PAS 1 which took off like a rocket with the pedals rotating much faster than I could pedal and required gearing up to slow down the pedal rotation but still accelerating much faster than my liking. I could use the throttle in PAS 1 but it was limited to the pedal assist speed at about 5mph. The stock display setting was set for 3 levels of assist. When I picked PAS 2 or 3, they also took off like in PAS 1 but even faster and required higher gearing. Throttle control allowed me to open up to over 25mph on level ground but I slowed down short of wide open throttle. I still have yet to determine the top speed of this setup.

I had read in the Programming the Bafang Middrive thread http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=58780&hilit=bb+programming that other riders had experienced similar acceleration from stop problems. So I needed to make up a programming cable. I had previously purchased a USB to TTL PL2303HX cable on e-bay for $4.49. I had originally planned to buy a display extension cable from em3ev along with the BBS02, but did not place any order with em3ev when I bought the unit from BTN. So I could not make a “neat” programming cable like pexio (July 2nd, Page 12 on this thread) so I came up with a temporary solution. I removed the square protectors on the ends of the programming cable and used heat shrink wire wrap on just the ground wire. I also took a jumper with female ends and also replaced the square ends with heat shrink. This arrangement allowed me to protect every other wire so there would be no short yet still fit in the tight male end of the controller cable.


I was then able to change my controller settings to match those of kepler (Sept 3rd, Page 18). The ride is much smoother now. I would strongly recommend you read the comments from Paul of em3ev (Oct. 12th , Page 22) and his updated comments on his website: http://em3ev.com/store/index.php?route=information/information&information_id=8. You should also read the instructions in the Programming Guide from http://www.emax-ebikes.com.au/faq.html. Be sure to write each of the 3 screens or you will not get all your changes as I found out. The advice I have is that you understand the controller changes you are making if you buy a Bafang unit with the stock settings and plan to buy or fabricate a programming cable. Otherwise, have the dealer customize the controller settings for you before you order. The Bafang software can be found at: http://ulozto.cz/x1zej9PD/software8fun-zipp

 

[RayGo]

So here are photos of the completed Schwinn e-bike.


Some of the Bike stats are as follows
29 lbs Weight of original bike
41 lbs Weight of e-bike with BBS02, rear cargo rack, dual kickstand
16 lbs Weight of 12s 36v 20Ah Lifep04 battery pack
21 lbs Weight of battery in trunk bag with tools
62 lbs Total weight of E-bike

So I have taken the Schwinn for 2 bike rides with my bike club on paved roads. The first ride was for 26.6 miles, averaging11.3 mph with 575 ft of elevation. I do not have a wattmeter on this bike now but the charger put back 4,837mA. The second ride was for 14 miles and required 2,517mA to recharge. That’s a ratio of 5.5 miles to 1 amp which is about the same as with my Specialized e-bike for the past year. With this ratio and a 20 Ah battery, I just might make the 100 mile rides.

I pedaled most of the time using mainly PAS 2 and 3 with all 9 assist level available to me. PAS is new for me and almost felt like cruise control. I hardly used any throttle control except from stop and when pointed uphill. When going uphill, I increased the PAS setting with no gear changes in some cases and lowered the gears with no PAS changes in other cases. So far, none of the “pulsing” or delay problems mentioned in this forum. I’m still experimenting with this setup and don’t have any preferences at this point but I am trying to be the most efficient to maximize distance. I found the ride to be very relaxing using PAS since I was not engaging the throttle, I pedaled at a nice and easy comfortable pace and the BBS02 is extremely quiet. Most of my fellow riders did not even know I had a motor setup until I flew past them going up a hill.

The Schwinn also feels faster with less effort than the Specialized e-bike. The Schwinn has the standard 46T chain wheel while the Specialized has a 34T chain wheel. The Specialized had good torque going uphill and could still reach almost 30mph on level ground with hybrid tires.

I’m planning on a few more upgrades. I plan to place an order with em3ev for their generic brake sensor for $12.50, a controller display extension cable for $8 and some spare chain wheels with different teeth configurations for $10 each. I plan to use the hall brake sensor as a kill switch and for changing gears under load. The extension cable with be used to make up my programming cable although I do not plan on any more changes at this time unless some interesting new developments arise from this forum.

So hopefully, this helps someone to go forward and order a Bafang mid-drive unit for their bicycle. It really is a simple installation process but be sure about the controller settings or program them yourself. That’s it for now.

 

[tomjasz]

Nice ride and a great post to learn from!

 

[gameofbikes]

Very nice looking bike, and very clean. Well done!

Where did you get the battery, and how much? What's the max discharge rate?

What kind of bag is that? I'm converting a bike to use the bb02 and i'm still shopping for the battery. I prefer frame-mounted, but I'm now considering something that could go ina cargo bag after seeing this build. Would you mind posting pics of the inside of the bag with the battery in it?

 

[opperpanter]

Thanks for the great post. This spring, I'll be putting a BBS02 kit on my Specialized Hardrock Comp hardtail from 2004

Do you a link to the eBay hub cone tool? Not sure what size I'll be needing.

 

[RayGo]

gameofbikes:

I built the battery myself with A123 20Ah pouch cells. You can find the info on my pack build here: http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=48947

The 12s 36v battery pack cost me about $400 in parts and I guess I got lucky and got good used A123 cell at about $15 each back in late 2012. I would not trust buying used/scrap A123 cells now and new A123 20Ah pouch cells cost about $58 each. I think the discharge rate is either 10C or 20C.

Here is the info on the bag at nashbar.com: http://www.nashbar.com/bikes/Product_10053_10052_563354_-1___204669

Here is a photo of the battery pack in the bag as requested:

While this setup works well for me on the Schwinn road bike, I find the center of gravity (cog) way too high on my Specialized mountain bike. The battery pack sits on its side which also adds to the cog being so high. It would be better laying on its face lowering the cog. I have another cheap tool bag that allows the pack to be mounted on the rack laying face down and that definitely helps. The battery pack weighs about 16 pounds which also adds to making the bike harder to handle. The original setup of my Specialized mountain bike had the NiMH battery pack mounted under the frame.

So the trunk rack was the only place available for mounting my new battery pack since the mid-drive unit takes up most of the frame on this Specialized bike. Since I don't want to buy or build another battery until this one dies, I decided to stay with the rear trunk mount on the Schwinn which worked out well. I also bought a backpack for holding this battery pack for use with the Specialized bike. I haven't gotten around to testing it yet but having a 16lb weight on my back is not appealing but should help with the cog issue when riding off-road.

Anyway, you should seriously consider a frame mounted battery since you have not yet bought a battery, especially if you are using it on a mountain bike for serious downhill or single track riding. I am thinking about a rebuildable frame mounted battery such as the following for my next battery build or purchase: https://ntsworks.com/battery/mini-48v-battery/

Good luck with your build.

 

[RayGo]

opperpanter:

Here is a link: http://www.ebay.com/itm/3-in-1-Bike-Chain-Whip-Bottom-Bracket-Freewheel-Wrench-Lockring-Tool-New-J-/121443156774?pt=LH_DefaultDomain_2&hash=item1c46938326

You can also search on "freewheel bottom bracket wrench" in E-bay. This tool only seems to come in one size. This tool worked well as a spanner wrench for the inner lock ring. However, the fit for the outer lock ring required filing the teeth down to get a good grip. I think it is easier to just use a strap wrench which I originally used.

You can also check out my comments on this tool on Dec. 10th at: http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=50104&start=3850

I'll be putting the 2.25in knobbies back on the Comp. This way I'll have both a Schwinn road bike for my on-road riding and a separate Specialized mountain bike for my off-road riding.

As I mentioned in the previous post, go with a frame mounted battery for your Comp to keep the center of gravity low and not effect your handling.