Bafang conversion with Nexus 8 speed internal hub

[etischer]

My build page is here with more info, I'll post a quick cut paste summary below. The conversion process took 4 hours, and the cost of conversion was about $600. Internal hub has held up to about 10 test rides from friends, and a weekend of use with my kid on the handle bars.

http://etischer.com/ebike/

On flat ground, at full throttle this bike will run 31.8 MPH without pedaling.

This is the bike I converted. I bought it on Craigslist because it had an 8 speed internal hub which allows you to shift while stopped, and also shift while you pedal. It also has a very clean look, no front or rear derailleurs, and no tensioner. The motor is barely visible behind the crank and main gear.

The motor is a Bafang BBS02 750 Watt, it's a Permanent magnet DC brushless motor, the controller is built into the motor housing, and the gear box uses helical gears so it is almost completely silent. The motor is rated 20 amps at 48 voltes peak.

I'm using 3 RC car batteries (4S Lipo) wired in series to get 44VDC, 5Ah. This gives me about 15 minutes of full current, at full throttle (typically just a few seconds of full throttle gets you up to 25mph, then the bike uses less current). Real world experience, I get about 15 miles using the highest pedal assist mode which gives me a cruising speed of 20 mph. Battery cost was $25/each

Batteries hooked up in parallel for charging, I can hook up to 6 in parallel and charge at once. The charger I'm using keeps track of how much energy (mAh) has been put into the battery, so I get a feel for how much capacity I have used up.

Pedal Assist Mode (PAS) (+) and (-) buttons on the left allow the motor to amplify how hard you pedal. The thumb throttle on the right will let you run the motor at full power without pedaling. The display is back lit at night which is nice. The brake levers that come with the Bafang kit include a brake switch that instantly shuts off the motor.

Again, full review is here http://etischer.com/ebike/

 

[joshseitz]

I'll be curious how it holds up. I am going to start with my standard SRAM 9-speed derailleur-based drive train, but I have another bike with an Alfine 8 that I may try as well. Only bummer with IGH is shifting under power. I've had it pop out of gear under human power and its no fun.

 

[Hillhater]

Very neat build..super stealth too !
Do you know what peak amps you are drawing ?
You will be giving those cells a hard time and they will return the favor with shortened life if you ride them hard.
I may be wise to double up the cell count to relax the load a bit.
Oh, and keep an eye on that seat post mount rack... they are not famous for being strong !

 

[Martog]

Nice clean build! And you're right - the black frame really helps with the stealthiness.

Can I ask where you acquired the kit and how long did you wait for it to arrive?

Seems like you found the one of the better (or best) deals I've seen so far for a BBS02/750w.

Thanks!
-Martog

 

[etischer]

The cells are rated 20C/30C, so that would be 100A continuous rating (150A for 20 seconds), the motor should be drawing only 20A. Not too worried about the batteries, they don't even get slightly warm even long runs at full throttle. I haven't measured the peak current draw, but I assume it's around 20A, the rating stamped on the motor. Not too concerned about current draw, I have a 5x factor of safety. I kinda like my little pack, it's easy to connect, only 3lbs... so far I haven't used more than 50% capacity on a ride. I'm a bit of a minimalist, I don't want to add weight unless it's necessary =)

Very neat build..super stealth too !
Do you know what peak amps you are drawing ?
You will be giving those cells a hard time and they will return the favor with shortened life if you ride them hard.
I may be wise to double up the cell count to relax the load a bit.
Oh, and keep an eye on that seat post mount rack... they are not famous for being strong !

 

[etischer]

Seller name was BTN (Let's back to nature) on Aliexpress. When you pay Aliexpress, they put the money in an escrow account, and the seller only gets paid when you give the OK, you get a few days to try the product out. I chatted with the seller (Amis) and he said he had the items in hand ready to ship, despite the 2 week lead time shown on Alibaba. 23 days was quoted on Alibaba from the time the order was placed, till the time it would arrive. I paid for the order May 26th, and received June 12th, so about 2 weeks. Amis was very responsive, every time I opened a chat window, he/she would respond within minutes, he/she also spoke english well.

My unit kept throwing up Err21, rendering the display useless. I let the seller know, he shipped me a new sensor within minutes of me chatting with him. I agreed to pay $20 for expedited shipping. New sensor arrived in 2 days and everything works perfectly.

http://www.aliexpress.com/store/705369

Nice clean build! And you're right - the black frame really helps with the stealthiness.

Can I ask where you acquired the kit and how long did you wait for it to arrive?

Seems like you found the one of the better (or best) deals I've seen so far for a BBS02/750w.

Thanks!
-Martog

 

[teslanv]

I started out with 6 of the 4S hardcase LiPo packs, but now only run with 3 for 5Ah of capacity. I really like the minimalist approach as well. And the bike + motor is so efficient, I don't need more than 222WHrs for most of my riding. I am also curious how your IGH will hold up over time. Keep us posted.

 

[etischer]

I did have one issue already with the internal hub. When I installed the motor, I left a little gap between the motor housing and the frame to allow the shift cable to be routed using the brazed on mounts. Turns out this was a bad idea, the motor eventually closed the gap which pinched my shift cable, causing it to shift very slowly, and I couldn't shift below 4th. I thought I for sure something broke or jammed in the hub, but luckily it was just the pinched cable. I'm mostly riding around town with my 3 year old, so it's not getting abused. I've had about 10 people test drive it so far, including some hard core mountain bikers, they have really put the hammer down on it and it's holding up well. Record so far is 36.5 mph on flat ground.

I got my err21 issue fixed. Seller sent a new wheel speed sensor and that fixed it.

I started out with 6 of the 4S hardcase LiPo packs, but now only run with 3 for 5Ah of capacity. I really like the minimalist approach as well. And the bike + motor is so efficient, I don't need more than 222WHrs for most of my riding. I am also curious how your IGH will hold up over time. Keep us posted.

 

[GiantEV]

How easy is it to pedal without any motor assistance? Is there any drag? I'd like to use this motor only for assistance on hills and the rest of the time use my own power.

 

[teslanv]

How easy is it to pedal without any motor assistance? Is there any drag? I'd like to use this motor only for assistance on hills and the rest of the time use my own power.

The drive had three internal freewheels IIRC. There is virtually no resistance when pedaling without motor power. With the exception of the additional weight and different center of gravity, you won't notice the drive when it's not under power.

 

[rjsimmo]

I have something similar in mind.
I have a Focus with internal hub and belt.
Does the hub handle the torque ok?
I need 35-42 Kmh cruising speed.
But most of the time i am up and down kerbs and on and off the road.
Have you heard of the 9PET coming out and how this will differ from the *Fun ??
How does the 8 FUN ride by the way ?
Cheers
R

 

[etischer]

Internal hub has been working great, only issue I've had was the cable getting pinched between the motor and frame, causing it to shift slowly. I've given a dozen or so test rides with avid riders, they've been cranking on it under full motor power and all is well so far.

I had waited a few weeks for the 9 FET, but got tired of delays and anticipation. I'm perfectly happy with the 6 FET, I don't need more than 20A, it's plenty fast and torquey for me. Cruising speed is 25mph for me on PAS 3, 40mph on down hill parts. I took the bike on a camping trip over the weekend, it climbs really well, to the point it will throw me off the bike going up hill before the motor will stall. The campground was pretty hilly, and leaving it in 3rd (of 8 speeds) was my preferred gear. Again, plenty of power!

I have something similar in mind.
I have a Focus with internal hub and belt.
Does the hub handle the torque ok?
I need 35-42 Kmh cruising speed.
But most of the time i am up and down kerbs and on and off the road.
Have you heard of the 9PET coming out and how this will differ from the *Fun ??
How does the 8 FUN ride by the way ?
Cheers
R

 

[etischer]

Upgraded my charger, I can now charge at over 19 amps, where my old charger maxed out at 3. Charger was around $60, and 24V power supply was around $60.

My low voltage monitors also arrived today

I've been climbing some super steep hills lately to the point the front wheel was barely touching the ground. Pretty impressive considering the comfort bike gearing.

 

[etischer]

I did 42 miles today, 36 straight though, then another 6 miles after a charge. Terrain was fairly flat, I tried to maintain 19 mph, using mostly assist 2.

My charger puts a full 20A into the pack.

I'm putting in the full 15,000mAh in 50 minutes.

 

[CdnE90]

How's the nexus holding up? I ride my bike as a daily commuter, and with the winter coming, I'd like to switch. I'm worried about durability.

 

[3Dkiller]

Nexus internal hub should be fine because i got the 7 speed version very smooth gear change with no delay.

 

[eMax]

I recently did a BBS02 with a Nexus 7 belt drive. I used the original Gates chainring and a 130BCD adapter for the BBS02. Very smooth combination.

 

[nesdon]

I know this is an old thread, but I'm working on a very similar conversion and form what I've read, I wouldn't think the belt line would be correct here. How did you manage that?