DIY Electric Bike With Bafang Mid Drive

[eximiusdeus]

Hi All,


I've been lurking on the forums for a while but this is my first post. Sorry in advance if I'm breaking any rules or asking something already answered. I've been researching to build an electric bike using a purchased road/hybrid bike and a bafang motor. Mostly, I plan on using it for commuting with a mix of day rides around cities. I'm going to buy the bike first and then buy the middrive (probably a bafang bbso2) later this fall, but I want to try to make sure everything is compatible before buying the bike. The bafang and a battery is ~13 pounds, and I'd really like to keep my bike under 40 lbs and lighter is even better because I'd love to use it (without being annoyed by the weight) with the motor off as well. Also, from what I've read, disc brakes are a must. I'm 6" 1' with longish legs and my lower back tends to hurt on aggressive bike frames, so I'm looking for a bike with a more endurance or comfort geometry.

So, two questions can I go with a carbon frame bike or should i stick to aluminum? Any thoughts on the below bikes generally and would they be compatible with a bafang middrive? From what I can find, Bafang middrives are compatible on any bike that has a 68 mm bottom bracket...but I feel like I'm missing something.

http://www.bikesdirect.com/products/...atbar-road.htm

http://www.bikesdirect.com/products/...e-roadbike.htm

http://www.bikesdirect.com/products/...ke-flatbar.htm

http://www.bikesdirect.com/products/...atbar-road.htm

http://www.bikesdirect.com/products/...atbar-road.htm

Thanks!

 

[Dewey]

Sorry I can't speak to Carbon or Aluminum as I've only ever ridden Steel bikes. But if you do get a bike with drop handlebars you might want to get ebrake sensors if you can't use the ebrake handles that come with the kit, you can choose either inline or a type that use a magnet attached to your levers, you may also want a gear sensor I recommend threading a new gear wire through as the fit is very tight and the sensor very fragile (my first one disintegrated when I tried pushing through a frayed end, $50 thrown away).

The BBS02 will fit either 68mm or 73mm bottom brackets, if you find you have the wider BB just go to a hardware store to buy some 5mm longer M6 screws and washers to mount the motor, you will probably lose the outer M33 locking ring in the process so you might want to also fit a BSB-1 torque arm attached with a hose clamp over a piece of old inner tube so as not to scratch the chainstay. I found the stock Bafang 46t chainring was geared a bit high for me, so you might also want to get a chainring adapter and smaller (or larger) Race Face chainring depending on your personal preference for your pedal cadence. Bafang mid-drives use a cadence sensor, if you want a torque sensor you might also consider a TSDZ2.

 

[eximiusdeus]

Sorry I can't speak to Carbon or Aluminum as I've only ever ridden Steel bikes. But if you do get a bike with drop handlebars you might want to get ebrake sensors if you can't use the ebrake handles that come with the kit, you can choose either inline or a type that use a magnet attached to your levers, you may also want a gear sensor I recommend threading a new gear wire through as the fit is very tight and the sensor very fragile (my first one disintegrated when I tried pushing through a frayed end, $50 thrown away).

The BBS02 will fit either 68mm or 73mm bottom brackets, if you find you have the wider BB just go to a hardware store to buy some 5mm longer M6 screws and washers to mount the motor, you will probably lose the outer M33 locking ring in the process so you might want to also fit a BSB-1 torque arm attached with a hose clamp over a piece of old inner tube so as not to scratch the chainstay. I found the stock Bafang 46t chainring was geared a bit high for me, so you might also want to get a chainring adapter and smaller (or larger) Race Face chainring depending on your personal preference for your pedal cadence. Bafang mid-drives use a cadence sensor, if you want a torque sensor you might also consider a TSDZ2.

Thanks for the reply, Dewey! That's super helpful!

 

[Deacon Blues]

Personally, I'd go with an aluminum frame over carbon.

 

[tomjasz]

The BBS02 will fit either 68mm or 73mm bottom brackets, if you find you have the wider BB just go to a hardware store to buy some 5mm longer M6 screws and washers to mount the motor, you will probably lose the outer M33 locking ring

Sometimes a second primary lock ring will fit. Personal bikes all have two primary lock rings rather than the aluminum secondary that needs an additional Shimano BB socket. Blue Loctite is the shiz!

I used. to produce these kits but it's easy to source locally. This is a photo of the lectricbike kit.

 

[Clyde]

We're in the same boat, as I'm at the beginning of the beginning of a bikesdirect.com / BBSHD build. I went aluminium for the stiffness and to keep my first build cost-effective.

 

[Pete12]

Here is a very helpful builders forum.

Home - Electricbike.com Ebike Forum

The Ebike Revolution starts here. Everything you wanted to know about high power and affordable ebikes.

electricbike.com

Another source for bafang kits is lunacycle.com

Built my BBSO2 2 years ago and have been quite happy with it. Whole bike is 43lbs. Held up well. Building your own brings some challenges, but I enjoyed it.

Pete

 

[tomjasz]

Here is a very helpful builders forum.

Home - Electricbike.com Ebike Forum

The Ebike Revolution starts here. Everything you wanted to know about high power and affordable ebikes.

electricbike.com

Another source for bafang kits is lunacycle.com

Built my BBSO2 2 years ago and have been quite happy with it. Whole bike is 43lbs. Held up well. Building your own brings some challenges, but I enjoyed it.

Pete

A Great motor for riders. (moped riders need not apply) Mine go back to 2014.

 

[tomjasz]

FWIW Many carbon bottom brackets can be a poor choice for a BBSxx series motor. It's really a budget motor and very self-sustainable. Lipstick on a pig IMO. Pig is the carbon frame with a high torque mid drive!. Some frames have a very thick BB not allowing a fit. WattWagon has a better idea with titanium motor mounts. A square taper BB would be bulletproof! Carbon fibre makes a lot of sense to me for road racers, but some hardcore acoustics are still modern metal tubbing. Thoughts?