New Bafang Crank-Drives

[footloose]

... some of the issues I would encounter in fitting a BBSxx to a 406 wheel bike.

Sam --

Moultons are great bikes, I'd love to have one.

I installed a BBS02 on a Raleigh Twenty with 406 wheels.
No problem with installation, it was dead easy.
However, I found that the BBS02 was overkill on that bike.
Combination of BBS02 power with small wheel, short wheelbase, very short chain-stays
makes for a bike that wants to do wheelies at slightest provocation.
Fun, but a bit hazardous for a commute bike :wink:

I'm removing the BBS02 from the R20 now, fitting it to a longer wheelbase bike with 700c wheels.

The BBS01 might be ideal for your Moulton. (If I was doing the R20 project again, I'd go for the BBS01.)

 

[Rusty123]

While ago I wrote here how I found some play in my Bafang cranks.
Tonight I checked and found out that the whole motor was loose at bottom bracket mount. Somehow the two thin nuts had loosened up (one is a lock nut).
I remember how I tightened them really hard. I tightened them again as tight I could with the right tool .
Maybe the reason for these loose parts is thermal expansion. My bike is used in -15 c temp outside and stored inside in +21 c temperatures. Another possible reason could be that my alu frame can't take the torgue of motor or the pressure of mounting.
Or maybe nuts and bolts allways get loose and I should check them more often

I was getting some creaking from my bottom bracket, so I checked mine a couple days ago. My locking rings were a little loose also. They seem to be made of pretty soft material, because when I tightened them up, the spanner wrench distorted the notches a bit.

I was also able to tighten the crank arms a touch -- though this is normal for newly installed crank arms on non-motorized bicycles also.

 

[deepfraught]

Does the installation use the bottom bracket threads, or does it thread one side of itself into the other, floating in the BB and clamping itself to the faces?

 

[Rusty123]

22 miles today (work commute, plus a side trip). At 15 miles, I still had 4 bars, which was making me think that either the readout was malfunctioning, or there was a small nuclear reactor hidden inside. But shortly thereafter, it dropped to 3 bars when climbing hills. By the time I got home, it was dropping to 2 bars during hill climbs.

Commuted four times this week (about 20 miles round trip, 80 miles total). As of yesterday, battery indicator was dropping to 3 bars at about 10 miles, and bouncing between 2 and 3 bars at 18 miles. I'm guessing that when the battery bank is brand new, it runs a little higher voltage, but after a few cycles, it settles down a bit.

 

[Rusty123]

Does the installation use the bottom bracket threads, or does it thread one side of itself into the other, floating in the BB and clamping itself to the faces?

The latter is basically the case -- the axle assemble is inserted into the BB shell, with a threaded retaining ring (and a locking ring, depending on BB width) compressing the unit against the BB faces. The internal threads on the BB shell do not come into play.

Incidentally, in some other threads, people were worrying that this would damage the BB shell internal threads, such that a normal BB couldn't be re-installed. I don't think this would be the case, because the threads are cut into the the shell, rather the shell being cut away from the threads.

 

[Rusty123]

I will be doing some changes to drive control also on this build. Plan to get rid of the thumb throttle and replace it with a push button that just gives a full throttle boost.

I really like the idea of a simple button for the throttle, but does anyone know for sure if the "deadband" is a function of the throttle switch vice the controller? If the latter, I guess a push button wouldn't solve the problem? And if the former, might the existing throttle be modified to eliminate the deadband? (I actually notice the deadband more when I release the throttle than when I engage it).

 

[footloose]

...floating in the BB and clamping itself to the faces?

Yes, basically "floats" in the BB.
You remove old BB; insert new drive from right hand side; thread a large diameter nut onto left side and tighten; add and tighten a second nut that acts as locknut. The first nut (if I recall correctly) has a couple of small "teeth" on the surface that mates to BB shell. They dig in slightly to BB shell, and serve to help keep entire assembly locked in position, though I'm skeptical about how much strength they actually add.

 

[Rusty123]

...floating in the BB and clamping itself to the faces?

Yes, basically "floats" in the BB.
You remove old BB; insert new drive from right hand side; thread a large diameter nut onto left side and tighten; add and tighten a second nut that acts as locknut. The first nut (if I recall correctly) has a couple of small "teeth" on the surface that mates to BB shell. They dig in slightly to BB shell, and serve to help keep entire assembly locked in position, though I'm skeptical about how much strength they actually add.

The "teeth" are actually on the "fixing plate", against which the nuts tighten.

Good diagrams and photos here: http://www.ebike-discount.com/online/templatemedia/all_lang/resources/BAFANG+CENTRAL+MOTOR+DRIVE+SYSTEM+-BDS01-+Feb+182013.pdf

 

[footloose]

The "teeth" are actually on the "fixing plate", against which the nuts tighten.

Thanks for the correction! I knew there was something not exactly right in how I remembered the assembly process.

 

[speedmd]

I would prefer a standard hex nut to the spanner nuts or have a bunch more notches in it as it is impossible to get to and tighten properly. A standard socket wrench would be much nicer to use and would allow a much more secure/permanent assembly.

 

[Rusty123]

I would prefer a standard hex nut to the spanner nuts or have a bunch more notches in it as it is impossible to get to and tighten properly. A standard socket wrench would be much nicer to use and would allow a much more secure/permanent assembly.

I have a tool like this: https://www.google.com/shopping/product/1263615695063837103?q=bottom+bracket+spanner&rls=com.microsoft:en-us:IE-SearchBox&psj=1&bav=on.2,or.r_cp.r_qf.&bvm=bv.59568121,d.cWc,pv.xjs.s.en_US.1EneOJbgwUk.O&biw=1680&bih=915&tch=3&ech=9&psi=Q33ZUomTDYvPsATepgE.1389985092774.1&wrapid=tlif138998509277410&ei=0H3ZUsDkH4vksAS5uYGADQ&ved=0CNoCEKYrMA04ZA

Which does a pretty good job, although as I mentioned earlier, the notches have distorted a bit. A hex nut would be easier to work with, though you would need a very large socket.

 

[speedmd]

I have one also, but with the bigger motor and the opposing swing arm pivot there is not enough room to get a good direct grab on it for the required amount of rotation.

 

[Rusty123]

I have one also, but with the bigger motor and the opposing swing arm pivot there is not enough room to get a good direct grab on it for the required amount of rotation.

Ahh, got it. Mine is non suspension, so no pivot arm to get in the way.

 

[deepfraught]

Thanks for all the replies clarifying the mounting method.

P.s. have a cross threaded BB frame, and another with dead BB, so this mounting method saves a replacement or repair.

 

[xpc]

Hi Guys, first time post, and I need some advise please. I want to fit a BBS02 48v 750w unit to my bike, turned it upside down to measure the BB and saw that the down bar is welded to the bottom of the BB as well as being forward. Will I have any problems in fitting a unit to this setup? I hope that someone can help me out.
Regards David (Xpc)

 

[Rusty123]

Hi Guys, first time post, and I need some advise please. I want to fit a BBS02 48v 750w unit to my bike, turned it upside down to measure the BB and saw that the down bar is welded to the bottom of the BB as well as being forward. Will I have any problems in fitting a unit to this setup? I hope that someone can help me out.
Regards David (Xpc)

I think it will mount up, but the motor will be under the bottom bracket, rather than in front of it. This may reduce your ground clearance. Similar to the cruiser bikes which have a curved down tube. Like this:

 

[xpc]

Thanks for that Rusty, I"m just using the bike for urban crawling, so ground clearance shouldn't be of much concern for me. The bike has had very little use, so I'm not too keen on having to buy another.
David

 

[samsavvas]

Footloose said: "Moultons are great bikes, I'd love to have one. I installed a BBS02 on a Raleigh Twenty with 406 wheels. No problem with installation, it was dead easy. However, I found that the BBS02 was overkill on that bike..."

Thanks for the feedback Footloose - I really appreciate it! The Moulton is an old APB and I recall that it has a longer wheelbase than the R20 (of which I too have owned a few). Nevertheless I think you advice is wise - I recall that I've actually 'wheelied' my APB riding a fairly steep hill with flat bars so it probably would tend to do the same with too much assist as well. I did read somewhere that a 'torque assist' model of the BBS01 is expected later this year so I may hang out for that one.

BTW my APB has the flat front and rear platform racks and is an ideal commuter (with 90psi tyres) as just about anything can be tied on and carried without fuss.

Thanks again,

Sam.

 

[spinningmagnets]

I'd still get the wider stator of the BBS02, but theres no need for using 48V on a smaller wheel, and the 36V would have a more affordable battery. Regardless of the amps that the stock controller provided, the assist level can be dialed-down for the desired power level (no wheelies).

I think there are around seven combinations of stator/voltage/controller. The one I'd recommend for the 20-inch wheels (or smaller) is listed as:

500W = 36V X 25A

 

[tomtom]

Hi guys. I want ask it is possible to mount this motor inside of frame ala Haibike http://www.dopedbike.com/wp-content/uploads/2010/12/haibike-xduro-eq-fs11.jpg


It look like in frame like this it is possible.

http://endless-sphere.com/forums/download/file.php?id=128245

 

[amigafan2003]

I would prefer a standard hex nut to the spanner nuts or have a bunch more notches in it as it is impossible to get to and tighten properly. A standard socket wrench would be much nicer to use and would allow a much more secure/permanent assembly.

You could use an M33 driveshaft nut - I think Citroens use them I believe.

 

[samsavvas]

I think there are around seven combinations of stator/voltage/controller. The one I'd recommend for the 20-inch wheels (or smaller) is listed as:

500W = 36V X 25A

Hi SpinningMagnets,

I'm having difficulty finding the BBSxx kit designated 36V X 25A. Most Asian retailers just seem to list:
36C X 250W
36V X 350W
48V X 500W.

Can you tell me were might I find the 36V version with the 25A controller that you recommend please? Or perhaps a retailer or site that lists all 7 of the versions you mentioned...

Thanks,
Sam

 

[Geebee]

You can select the voltage on the 500W version
http://www.bmsbattery.com/89-central-motor

 

[Tom L]

I made it up the mountain no fuss. Started at about 450m and rode to 1271m over a distance of 11km. Trip time was 27 minutes.

In PAS3 (of 5 levels) I was assisting with light to moderate peddling. A very easy ride. I averaged 24km/h with the minimum speed I noticed 19km/h. I stopped momentarily half way up to check the motor temp. It was warm but I could easily hold my hand on it. This was about the same at the top. Whenever I looked the power assist was between 550W and 650W. I have a recorded peak of 705W and 15A.

I consumed almost exactly 250Wh for an average efficiency of about 23Wh/km. Not brilliant by any means but I was more interested in the motor's ability to sustain an uphill load. Which it did well.

I got a few funny looks from other cyclists on the way (passed one Lycra) but no comments. A kid on an ICE bike turned up while I was at the top. It was damn noisy and his back wheel was so out of true it looked like a clown bike bobbing away. I would not like to have ridden that back down. Speaking of which, I clocked over 60km/h going down the mountain (in a 50km/h zone, oops) then the speedo started playing up and jumping values randomly. I overtook a postie bike too.

The battery gauge seemed quite accurate though it did read low due to voltage sag nearing the top. Once allowed to recover it went back to two bars (I have ~560Wh capacity). The minimum voltage I have recorded as 42V and it recovered to 45.5V.

 

[deepfraught]

Nice climb review Tom. What gear(s) and cadence were you operating assist at? The kit is 750w with batt from LC?