New Bafang Crank-Drives

[Hillhater]

The way I'd ideally ride this setup... Put it in one gear, then vary the power assist from 1-5. I'm not saying it is efficient or logical.... Just that it might feel very natural to "shift" power assist rather than gear ratio with this kit.

I dont understand,..
If the motor has enough torque to start of in "one gear".. ( presumably one high enough to give a suitable cruise speed).. then why mess about with various "power levels" ?
Wouldn't you simply max it out from the off ? ( dont tell me there is too much torque ? )

 

[--freeride--]

130 mm bcd is not a good choice for this kit IMO. It will force you to go to a wider chain line. Looking like something in a 155 -160 bcd minimum to go inboard the stock ring. 144 bcd / 42 tooth rings look like they will rub the case without some serious mod and leaves not much meat to mount it, just going by a quick looksee. I have to find/ make a thin spacer for mine and will see what will fit and clear the chain stay a bit closer over the weekend. If mounting a second or larger ring outs side of stock ring, its mount will need to go outside the inward jog the stock ring makes and most stock chain wheels will need to be opened up to clear the stock rings jog/ center. Something like a 44 -54 would work well on this and give a much broader speed range and allow more use of larger rear cogs.

If you want to use an offset Chainring like the stock one, then 42-43 is the limit and you already need an CNC artist to built this chainring from aluminium. That will be very expensive.

What I think is, when you put a stock Chainring, no matter if 104mm 4 hole/ or 110mm/ 130mm 5 hole on the inside of a spider and shim it to the nearest position to the trany (where it does not grind on it), you only lose 3-5mm in the chainline compared to the stock chainring.
if you do that you can go down to 40T or even 39T. With a 38T, a french guy had to grind of a bit from the plastik tranycover for making room for the chain.
This opton is Chainring as near as possible to the plastik cover, and the Chain is the limit!

So 130mm Chainrings with 39T/40T could be a good choise for running this option. Going any smaller means grinding at the tranycover or moving another 3-4mm out with the Chainline.
I would choose 104mm 4hole for MTBs becouse there are bashgards available, they save your sprocket and keep the chain in place. I want to do trial stepups with this motor

Two Chainrings up front makes the chainline much worther. That could be an option in a trike or a Velomobil where the chain is extremly long and the chainline does not matter that much.

I will try a 8speed Cassette in the rear with 13-20-26-34-42, giffing me a wide range. Using only 5 gears I can move them out to get a better chainline. In the front I try the stock 46 first. Then I try the adapter with a 40T 38T.

Mayby i stick with the 46T when the climbing abbilities are fine with the 42T in the rear.

 

[coachstevo]

Hey footloose,

What is your rear gearing?
I'm just north of you and have a kit on the way for my yuba Munro, wondering if you are able to grind up some of the hills down there?
I have two short nasties on my commute (20% for a bit mor than 1/4 mile each), the DD rear set up I have just can't handle them and so I suffer up each one!

 

[Kai]

Those who have C961 display (white frame), should know that the secret key combos for menu is press and hold plus and minus,
In menu you can set max speed, backlight brightness etc.
From menu you can open advanced menu by pressing and holding plus and minus and pressing power 8 times.
In advanced menu you can set wheel diameter, PAS power level and PAS cutoff time

 

[footloose]

The way I'd ideally ride this setup... Put it in one gear, then vary the power assist from 1-5. I'm not saying it is efficient or logical.... Just that it might feel very natural to "shift" power assist rather than gear ratio with this kit.

I dont understand,..
If the motor has enough torque to start of in "one gear".. ( presumably one high enough to give a suitable cruise speed).. then why mess about with various "power levels" ?
Wouldn't you simply max it out from the off ? ( dont tell me there is too much torque ? )

Couple reasons.
I'd like to get some exercise, so don't want max power all the time.
This bike is a wheelie machine even foot powered on hills, and max power on steep hills does lift the front even in high gear -- safer to climb them a bit slower on lower power setting.
Seems like it might conserve battery power.
Last, a bit safer in stop and go traffic possibly.

Not sure all these reasons make sense or hold up logically.
But I can imagine that shifting power settings rather than gears could work on this setup.

I do similar on my Mac setup with three power settings... Change them on fly, more often than I actually change physical gear.

 

[speedmd]

If you want to use an offset Chainring like the stock one, then 42-43 is the limit and you already need an CNC artist to built this chainring from aluminium. That will be very expensive.

I would use the stock ring as the spyder. Simply turn (on a lathe) out the center of the new rings to fit. Align / drill / mount. Simple as long as the rings have enough metal to fit mounting holes. Tightest chain line possible with the kit other than possibly squeezing a few more millimeters with a custom made offset spyder.

For trials, you are stuck with the wider chain line. Pinion gear bump will limit how close/ small you can make it. 38 tooth may be possible without adding even more chainline offset. This is more of a general purpose kit, but the same concept with a tighter chain line and larger reduction would be great for a trials specific drive. Look forward to seeing your build.

cheers

 

[--freeride--]

Those who have C961 display (white frame), should know that the secret key combos for menu is press and hold plus and minus,
In menu you can set max speed, backlight brightness etc.
From menu you can open advanced menu by pressing and holding plus and minus and pressing power 8 times.
In advanced menu you can set wheel diameter, PAS power level and PAS cutoff time

Are you sure that you can set powerlevels? Can you change the cadence settings too? Then we would have everything we need!

 

[footloose]

Hey footloose,

What is your rear gearing?
I'm just north of you and have a kit on the way for my yuba Munro, wondering if you are able to grind up some of the hills down there?
I have two short nasties on my commute (20% for a bit mor than 1/4 mile each), the DD rear set up I have just can't handle them and so I suffer up each one!

I have an 18 tooth sprocket on rear, with an 8-speed Shimano IGH and 20" wheel.

On the Shimano, 5th gear is 1:1 ratio.

With power set on high, and reasonable pedaling on my part, 5th gear will get me up my steepest local hills at good speed.
With power set on low, and some pedaling on part, 3rd gear will get me up the same hills at good speed.
With power set on high, no pedaling, 3rd gear will climb the hills briskly.
I think that if I had power on high and was in 1st gear, it would climb a tree.

Should be an ideal setup for your Yuba Mundo!

 

[--freeride--]

Those who have C961 display (white frame), should know that the secret key combos for menu is press and hold plus and minus,
In menu you can set max speed, backlight brightness etc.
From menu you can open advanced menu by pressing and holding plus and minus and pressing power 8 times.
In advanced menu you can set wheel diameter, PAS power level and PAS cutoff time

I soldered the Battery conector to my drive and testet. Kai is right you can adjust the NUMBER of PAS power levels the wheel size and the minutes after what the display atomatically switches the system off...
But thats it. You can not adjust the settings of the PAS levels...

By pressing and holding plus and minus and pressing power 8 times in the advanced menu the Display clears all your settings and everything is like it came from the factroy.

Now I know the poor menu of the display, but that does not help me change those damn stock cadenze and Power settings..

 

[glend]

You could just run a SRAM DualDrive hub. It has a standard 8/9/10 speed freehub body.

http://www.sram.com/sram/urban/products/sram-dd3-24

Perhaps better to look at geared hubs rated for tandems because of the potential of overloading the gearing system (legpower + bafang) . If cost wasn't a concern the Rohloff Speedhub would fill the bill admirably.

 

[Warren]

I am pretty sure the Rohloff is the only IGH that would stand up to two strong people on a tandem...very high torque pulses.

I have no doubt you can wreck any other IGH on an e-assist running through the gears, if you want to. But with a little common sense, many should hold up fine. Always starting in low gears, and easing the power on, an e-assist can actually be easier on a drivetrain than pedal only. My chains last at least twice as long on my e-assist as on my pedal bikes.

 

[glend]

Excellent points warren.

 

[neptronix]

Quick question - and sorry if it has been covered already.. I haven't read every page.

But BMSbattery is selling a BBS02 model rated for 500W.

http://www.bmsbattery.com/central-motor/636-48v350w-bbs01-bafang-central-motor.html

Total cost delivered to my door is about $500 ( they don't seem to be gouging on shipping for this item ). That's a decent price.

The question is - does the 500W model really have the wider stator? or just the wider casing?

If so, it would be a good candidate for running with an external controller, which would remove some of the heat from inside the case, allowing you to push it like mwkeefer did & also save a few bucks in the process over the 750w model..

 

[wineboyrider]

Quick question - and sorry if it has been covered already.. I haven't read every page.

But BMSbattery is selling a BBS02 model rated for 500W.

http://www.bmsbattery.com/central-motor/636-48v350w-bbs01-bafang-central-motor.html

Total cost delivered to my door is about $500 ( they don't seem to be gouging on shipping for this item ). That's a decent price.

The question is - does the 500W model really have the wider stator? or just the wider casing?

If so, it would be a good candidate for running with an external controller, which would remove some of the heat from inside the case, allowing you to push it like mwkeefer did & also save a few bucks in the process over the 750w model..

This thread has a lot of interest and traction and I was the first to post on this thread that bmsbattery.com has the bbs01 kit, but mwkeefer covered it thoroughly on page 23 or so..

 

[neptronix]

I see nothing about the 500W unit i'm talking about here on page 23 or 24.

I think you missed some details in my post

Must be so new that nobody knows about it..

 

[wineboyrider]

mwkeefer wrote:Hello again!

I just saw this confusion and figured I would explain what BMS Battery is offering and how misleading their specs are, also what the real specs are:

1.) All systems from the BBS-0X line are programmed at the factory with certain features, their power level doesn't matter... this can be complicated to explain and I will save this for my post later this weekend on everything technical about the Bafang crank drive system, it's also not important to the current confusion and would just add to it.

2.) The motor is identical to all BBS-01 350w systems, the controller limits the current to 16 or 18A, this particular unit appears to be limiting to 18A - see #3 for why. That means spinningmagnets you are correct in that the input power would be: 769.6 @ 16 or 865.8w @ 18A and 48.1v nominal - using the same tested (I tested it) 80% maximum efficiency of this system in general it translates to crank power of: 615.68w @ 16A and 668.712 @ 18A and 48v nominal.

3.) The LCD pictured is from the very first production line of the bafangs however, they haven't changed much but the color from white to black in the C961 model which is what they are picturing. This tells me when it was produced and since I had one I also know the remaining specs for these units.

4.) I would bet 1.00 that the chainring is a 48t variety, almost all the stock kits are - according to Bafang 80% of the first batch they built (all the various derivatives) were 48t, some were 46t and since these aren't new - unless someone ordered a pallete of 47 custom made and BMS Battery bought em up cheap, they must be 48t

The shipping will likely be expensive and you must check for warpage and bending of the chainring, crank arms and other parts upon receipt to be sure you receive a useable drive system but the price (without shipping) is quite fair and it would be worth a guinea pig.

I nearly forgot to mention, these will run quite nicely on 15S lipo too (charged to 62.25-62.5v maximum pack voltage) - at that voltage they are quite a bit quicker and use 888w to 999w at 16 to 18a nominal, at 16A the output to the rear cassette or freewheel is 710.4w which is fully legal in the USA and mathematically provable. One could even argue that the 799w output from the crank case on 18A would be no more than 750w at the street due to mechanical losses of the freewheel, chain and rolling resistance.

Guess I'm saying these are worth the purchase if the shipping costs are kept low enough, downside - I order all my things from BMS Battery as EMS shipped to ensure they arrive intact and functional without damage.

Regards,
Mike aka mwkeefer
Regards,
Mike

{My Rides]
2010 Dahon Jack - GNG v1 - LYEN 6FET - 20/40A - 18S2P10AH - Nom:66.6v,1332w
2004 Hard Rock Pro Disc - Recumpence ms eDrive v4 - Astro 3220 4T - 12S2P16AH - HV110 - Left Side Drive - Gearing: 38mph
Nominal Peak Power @ 60 seconds: 5328 watts - Maximum Power: 49.8v, 120A, 5872w
2010 Downtube 8FH - Stock GNG v1 Stock Controller - EB809XC - 12-16S
2012 Downtube Nova 7spd - Stock GNG v2 - 12S2P10AH - EB809 - 12S-16S - 20A/30A,Nom VCC: 44.4, 888w
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mwkeefer
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Posts: 2420
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Location: Malvern, PA USA

 

[neptronix]

He is answering a question about the 350w unit, which looks like the smaller stator version.
There is no mention of the 500w unit any where near that post that i see.

My question is whether or not the 500w unit has the same stator as the 750w model or not. If it does, it would be ideal due to the lower price to run a hopped up external controller with.

 

[Kepler]

Reading all I can and making a few assumptions, I believe the 500W version is mechanically the same as the 750W version. Both I believe are using the lower kV motor to suit 48V. However, I think the 500W version has a lower current limit set in the controller.

I would personally still go for the 750W version form Aliexpress. Price is not much different and they will custom program for you on request. I have had email confirmation that the speed limiter and LVC has been set as per my request. These drives are taking 25 to 30 days from placement of order to delivery.

 

[lantice13]

the 48v 500w kit from bmsbattery got a stamp BBS02. So I would assume this is the same stator as the 750w version with just a lower spec controller.

 

[spinningmagnets]

These are the questions that bug me. Wish I could buy every possible version and pull them apart. Here's my best guess:

Regardless of the rated output wattage (which is specified due to legal power limits in various countries, 500W in Canada, 750W in USA, etc) the key piece of evidence is that the factory seems to be using the same mechanical drive for all units.

So...for the output RPMs of the drive to remain the same, all 48V windings will be at a lower Kv compared to the 36V windings. The 36V 200W/250W/350W units were never anticipated to do well in North America, and I'm not sure that Bafang was certain that this drive would do well at all. Of course they ended up being pleased with the European/Asian response...pleased enough to develop a model with more voltage and capable of higher amps (more copper) for us.

For the 48V/500W unit to have higher voltage and amps, but have a smaller stator than the 750W unit, we would have to believe that Bafang is producing a 3rd size of stator (I'm guessing no). This is intriguing because some vendors will be selling the 500W unit cheaper than the 750W unit, so anyone who intends to use an external controller would save a few bucks (and also be able to buy a unit at times when the 750W is out of stock).

Another piece of good news, I am getting reports that the stock crank spindle is very strong (unlike GNG), and is standing up to some serious abuse.

 

[spinningmagnets]

The ebike retailer "alcedoitalia.it" (in Italy), is making a 42T sprocket for the Bafang BBX-XX series. I only mention it because their pic of it clearly shows the chainline off-set that is needed:

http://www.alcedoitalia.it/shop/guarniture/corona-42-denti-per-bafang-centrale-bbs01/

 

[neptronix]

You're right. the price difference on aliexpress is only $34. I didn't even consider buying from there.
My bad.

But if you're going to rip the controller out as soon as you get it, May as well save a few bucks.

Then again, mwkeefer upped the shunt and got more amps out of his, ya? Maybe the 750W is worth getting if you don't want to get crazy. As long as you can bypass any limitations on it.

 

[--freeride--]

I am pretty sure the Rohloff is the only IGH that would stand up to two strong people on a tandem...very high torque pulses.

I have no doubt you can wreck any other IGH on an e-assist running through the gears, if you want to. But with a little common sense, many should hold up fine. Always starting in low gears, and easing the power on, an e-assist can actually be easier on a drivetrain than pedal only. My chains last at least twice as long on my e-assist as on my pedal bikes.

Are you using Hubmotors or midmotors? The chain on my Panasonic midmotor bike i bought with an super weak 350w motor looked misserable after 3000k. The tool for measuring the chain did not even fit anymore the chain was about 3mm longer on 20cm!

On the 750W Bafang with hard abuse I would say 500-1000k is a reakistic chainlife.

 

[Warren]

"Are you using Hubmotors or midmotors?"

I am using a "350 watt" MAC, as a mid-motor. You need to understand that I am a complete outlier on this site. I am sure I am easier on my bike than anybody here. I find 250-350 watt mid-drives perfect. Most people on here want a moped.

 

[amigafan2003]

Reading all I can and making a few assumptions, I believe the 500W version is mechanically the same as the 750W version. Both I believe are using the lower kV motor to suit 48V. However, I think the 500W version has a lower current limit set in the controller.

Hmm, that might be an option for those intending to run 15s lipo on it (i.e. me) as a way to keep the amp draw down.

I'm so close to pulling the trigger on that 48v500w unit - just need some way of adjusting the max rpms and lvc (not that I'd ever rely on the lvc).