Help Me install BPM axle

[Beagle123]

Hi:

I recently purchased a Bafang 48v 500w 201rpm (Code 14) motor from BMSBattery.com. They didn't include any nuts or torque washers with the motor. It Just had a bare axle. I would like to learn the proper way to install these hubs.

The problem that I'm having is that there's no bolt to support the frame on the free wheel side, so when you tighten the axle nut, the frame would hit the 7 speed freewheel:



If you look at this picture, you can see that there's nothing stopping the frame from squeezing against the smallest gear when I install this wheel.

The problem is here:



There is supposed to be some type of nut to provide support against the frame. Then when you install the axle, the two nuts pinch against the frame, holding the axle secure.

Here is a picture of the back hub that was removed from the bike. It has a proper nut to support the frame. You can see how the frame would be pinched in between the nuts:

View attachment 1

Here is a picture of the BPM motor's axle without the free wheel:




What is the proper way to install this hub? Shouldn't it have a nut like the one above? What parts am I missing?

Also, where can I buy those special nuts for securing the axle and torque washers. The axle is 12mm, but the threads don't look normal to me. I think they are fine threads. For example, if you bought a 12mm bolt at the hardware store, I don't think it fits. I tried a bike store and home depot already.

Thanks,
Eric

 

[chisixer6]

I think you need a spacer between freewheel and frame, none of my 7 ebikes has an inner nut, just spacer...
You might try Home depot and look at their bins od mm nuts, if you can, bring your hub to try axle on for fitting.

if that fails, see if ebike.ca will sell you some.

 

[Beagle123]

Hi chisixer6:

Thanks for the help. So the spacer that you talked about is just a 12mm inside diameter tube right?

Does that normally come with the motor? What is the standard set-up you get when you buy from a normal vendor? (not a scumbag like BMSBattery)

I've already gone to two hardware stores and two bike shops. The threads don't fit either 12mm standard or fine threads. They're something different. I don't know what. Has anyone else had to find an axle nut for these before?

 

[friendly1uk]

Your arrow is pointing too a tabbed washer.

I just got a cst. It came with a couple of resealable parts bags. Tabbed washers, nuts and plastic nut covers. Controller related parts as well. All mixed up and spread across 3 matching little bags.

 

[sal_park]

I got the same experience as the last poster (3 plastic bags) but I ordered the kit, not just the motor. For my frame I needed to use the included ~5mm washer and tab lock washer inside the frame on the gear side

 

[chisixer6]

Beagle123;

I google mm threads and got 2 12mm thread 12mm x 1.75 and 12mm 1.25

here's the chart

Tap Chart - Metric Threads




Tap size Basic major
dia (mm) Basic major dia
(inch) mm per thread Drill size
(mm) Drill size
(inch)
M1.6 x 0.35
1,6mm
.0630
.35
1,25mm
#55

M2 x 0.4
2mm
.0787
.4
1,6mm
#52

M2.5 x 0.45
2,5mm
.0984
.45
2,05mm
#46

M3 x 0.5
3mm
.1181
.5
2,5mm
#39

M3.5 x 0.6
3,5mm
.1378
.6
2,9mm
#32

M4 x 0.7
4mm
.1575
.7
3,3mm
#30

M5 x 0.8
5mm
.1969
.8
4,2mm
#19

M6 x 1
6mm
.2362
1
5mm
#8

M8 x 1.25
8mm
.3150
1.25
6,8mm
H

M8 x 1
8mm
.3150
1
7mm
J

M10 x 1.5
10mm
.3937
1.5
8,5mm
R

M10 x 1.25
10mm
.3937
1.25
8,8mm
11/32

M12 x 1.75
12mm
.4724
1.75
10,2mm
13/32

M12 x 1.25
12mm
.4724
1.25
10,8mm
27/64

M14 x 2
14mm
.5512
2
12mm
15/32

M14 x 1.5
14mm
.5512
1.5
12,5mm
1/2

M16 x 2
16mm
.6299
2
14mm
35/64

M16 x 1.5
16mm
.6299
1.5
14,5mm
37/64

M18 x 2.5
18mm
.7087
2.5
15,5mm
39/64

M18 x 1.5
18mm
.7087
1.5
16,5mm
21/32

M20 x 2.5
20mm
.7874
2.5
17,5mm
11/16

M20 x 1.5
20mm
.7874
1.5
18,5mm
47/64

M22 x 2.5
22mm
.8661
2.5
19,5mm
49/64

M22 x 1.5
22mm
.8661
1.5
20,5mm
13/16

M24 x 3
24mm
.9449
3
21mm
53/64

M24 x 2
24mm
.9449
2
22mm
7/8

M27 x 3
27mm
1.0630
3
24mm
15/16

M27 x 2
27mm
1.0630
2
25mm
1

chart didn't load good, here's the link

http://www.carbidedepot.com/formulas-tap-metric.htm

the spacers I was referring, you can use washers that fits over the axle, the thicker the better.

I think the thick spacers came with my yescom kit.

you can also find thick washer at Home Depot, not the bag spacers, find them in the section where you pull out the drawers, you might find your 12mm nut there too.

when your freewheel is rubbing the frame, add washers or spacers until the freewheel doesn't rub anymore.

 

[-dg]

Does that normally come with the motor? What is the standard set-up you get when you buy from a normal vendor? (not a scumbag like BMSBattery)

I've already gone to two hardware stores and two bike shops. The threads don't fit either 12mm standard or fine threads. They're something different. I don't know what.

The thread size is labeled in the diagram you posted, M12x1.25.

I just received one of these motors. You should have gotten a little bag with at least a spacer, two flat washers, two anti-torque washers, two nuts, two rubber end caps, and maybe an electrical connector shell for the hall sensor leads if your motor is sensored. If you have not done so, email the vendor and ask for the missing parts, they were supposed to come with the motor so it was mis-packed or they were lost in transit. I can't speak about BMS battery, but Greenbikekit were happy to send me the correct cable for my other motor in place of the incorrect one they had originally shipped. It arrived in a few days, no charge.

 

[Beagle123]

Hey. Thanks. Now I see it in the diagram. The threads are 12mmX1.25. Thanks dg.

I wrote to BMS Battery, and they aren't responding to my emails. I've heard from others here that BMSBattery will no longer respond to email after they ship the product. I didn't get the bags of parts you mentioned. Just bare axles. I have a good specialty fastener store near me, and now I know what I need. I'll fix it myself and never do business with BMSBattery again. I should have listened to others here, and avoided them.

 

[-dg]

Hey. Thanks. Now I see it in the diagram. The threads are 12mmX1.25. Thanks dg.

I wrote to BMS Battery, and they aren't responding to my emails. I've heard from others here that BMSBattery will no longer respond to email after they ship the product. I didn't get the bags of parts you mentioned. Just bare axles. I have a good specialty fastener store near me, and now I know what I need. I'll fix it myself and never do business with BMSBattery again. I should have listened to others here, and avoided them.

How long ago did you write to them?

Another idea, you might write to sales@greenbikekit.com and explain that you had a bad experience with the other vendor and they did not send the small parts that go with a BPM and would it be possible to order just the nuts and especially anti-torque washers and end caps. I don't know that this will work, but they seem to be at least trying to provide better service. Or perhaps post an appeal here with title asking for the washers in items wanted, maybe someone has a dead motor and will give you some.

You don't need the flat washer or the nuts as you can get better ones, the factory ones are not all that great. But, you do want the anti-torque washers and the end caps would be nice to have but could be worked around.

 

[docnjoj]

Hey. Thanks. Now I see it in the diagram. The threads are 12mmX1.25. Thanks dg.

I wrote to BMS Battery, and they aren't responding to my emails. I've heard from others here that BMSBattery will no longer respond to email after they ship the product. I didn't get the bags of parts you mentioned. Just bare axles. I have a good specialty fastener store near me, and now I know what I need. I'll fix it myself and never do business with BMSBattery again. I should have listened to others here, and avoided them.

hey Beagle123
Rumor has it that some auto lug nuts will have a similar thread, Might be worth a trip to the auto supply store.
otherDoc
edit: These guys have them cheep.
http://www.zorotools.com/g/00056749/k-G2073355?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&kw={keyword}&gclid=CM-hyNSJibcCFcw7OgodhAQAqA

 

[Beagle123]

Hi:

Thanks for your help. I've solved the problems:

I found these nuts at a fastener super-store called "King Bolt."



The nut on the left is perfect for maximum friction against the frame. The one on the right is narrower so I used it as the spacer to separate the frame from the freewheel. Its actually a little too large, so I had to adjust the cable going to the derailer, but in the end it works perfectly. I opted for a nut instead of a spacer because I want both the nuts and the axle to meld into one solid piece, to help the torque washer prevent the axle from torquing around. A washer or spacer wouldn't grab the axle to prevent it from spinning as much.



I'd still really like to know the proper way to do this. I plan on building and selling ebikes, so hopefully I will be doing this a lot. I still don't understand how its done normally. When people buy one of these motors, the axle on the freewheel side seems to have nothing to brace against the frame. What gives? That half nut works fine, but obviously most people don't have access to that exact part. What is the typical part used?



Hey otherDoc, I have a question for you:

Are you called otherDoc because you specialize in giving second opionions?

Eric

 

[lbz5mc12]

All you needed for that was a thick washer. The nut might be spreading your dropouts too far apart and messing up your rear frame alignment. Also if the gap is too large your chain may slip off and get wedged in between the frame and the gear.

 

[docnjoj]

Hey otherDoc, I have a question for you:

Are you called otherDoc because you specialize in giving second opionions?

Eric

Nah! When I joined in 2008 or so there was only one other doctor and he is DrBass! I retired from practice in about 1986 or so, but when it comes to E-bikes, he is the real doctor! I'd accept his 2nd opinion (or his first, for that matter)anytime! Glad to see you active again, beagle123.
otherDoc

 

[Beagle123]

Thanks lbz5mc12. I see what you're saying. I'll try that. The fit was very tight, I need to really push on it to get the extra few mm of separation.

Thanks doc. So you guys are real doctors. Very impressive. I thought you were just using the names i.e. Doctor-is-in-the-house, doctor-of-love etc.

I think it might be time for this thread to die a natural death.

 

[-dg]

I found these nuts at a fastener super-store called "King Bolt."

Good so far.

The nut on the left is perfect for maximum friction against the frame. The one on the right is narrower so I used it as the spacer to separate the frame from the freewheel. Its actually a little too large, so I had to adjust the cable going to the derailer, but in the end it works perfectly. I opted for a nut instead of a spacer because I want both the nuts and the axle to meld into one solid piece, to help the torque washer prevent the axle from torquing around. A washer or spacer wouldn't grab the axle to prevent it from spinning as much.

Yikes! Beware. I have underlined the scary bits.

I'd still really like to know the proper way to do this. I plan on building and selling ebikes, so hopefully I will be doing this a lot. I still don't understand how its done normally. When people buy one of these motors, the axle on the freewheel side seems to have nothing to brace against the frame. What gives? That half nut works fine, but obviously most people don't have access to that exact part. What is the typical part used?

I can't tell precisely from your photos, but this does not look like a secure or durable arrangement to me.

Where are the torque washers? You never received any and there are none visible in the photo. So all that is preventing the axle spinning is the clamping force of the nuts. This is probably not enough for big motor like the BPM. It will spin and damage both the motor and the bike frame. You need at least the torque washers and possibly also anti-torque arms. Here is a photo of the anti-torque washer that you did not get. These go where you have the half nut.

Also, when they use half nuts on real bike hubs they are jammed against the bearing cone nut so neither of them can rotate. A nut on each side of the same dropout as you show cannot prevent the axle from spinning, it can just move sideways through the bike as it turns on the threads.

 

[Beagle123]

Hi dg:

I'll show you how I did it, and you can let me know if I can improve it. First, I found a torque washer form an old bike. It is on the left side with the half nut:



So on that side it has a torque washer and the steel frame.

On the other side, the derailer has a black "C" shaped fitting that goes over the axle. Its also made of steel, so it should be very strong. It fits the axle snugly, and has a bolt that tightens it in place:



I think its pretty good. I'm planning on only running about 750 watts, so I doubt it will spin. However, I'm open to second opinions. (otherDoc?? )

 

[d8veh]

I've been away for a few days, so sorry I didn't reply earlier. BMSBattery supply the nuts and washers in a separate little bag in the box with the controller or sometimes just thrown in the main carton, so have a good look through all the stuff they sent.

To space the free-wheel from the frame, I usually use two standard 12mm washers with the O/D filed down to fit, or two 10 mm washers (I think) with the hole opened out to 12mm.

With those type of drop-outs, you need at least one torque arm. I wouldn't personally use those type of drop-outs for a high-torque motor like the BPM. I'd prefer one where the axle is fully home - not stuck in the middle of a long slot.
http://www.bmsbattery.com/450-a-pair-of-ebike-torque-arm.html

If your thinking of selling them, get a disc brake bike and fix the torque arm to the disc-brake mount like this:


You'll find your gearing is too low with that free-wheel, you''ll need a 52T chain-wheel or a free-wheel with 11T top gear.

 

[-dg]

With those type of drop-outs, you need at least one torque arm. I wouldn't personally use those type of drop-outs for a high-torque motor like the BPM. I'd prefer one where the axle is fully home - not stuck in the middle of a long slot.

At least turn the torque washer the other way so the axle can be slid all the way back in the dropout. I think replacing the half nut with another torque washer on the inside might be a good idea too, so that there would be two torque washers, one on each side. A torque arm on the outside is good too.

D8veh, I got a pair of the torque arms from greenbikekit and they are ... not very nice ... thin, bad fit on the axle... the cheapest possible stamping with old worn dies... is the bmsbattery one any better? Are any of the usual suspects making decent ones?

 

[d8veh]

With those type of drop-outs, you need at least one torque arm. I wouldn't personally use those type of drop-outs for a high-torque motor like the BPM. I'd prefer one where the axle is fully home - not stuck in the middle of a long slot.

At least turn the torque washer the other way so the axle can be slid all the way back in the dropout. I think replacing the half nut with another torque washer on the inside might be a good idea too, so that there would be two torque washers, one on each side. A torque arm on the outside is good too.

D8veh, I got a pair of the torque arms from greenbikekit and they are ... not very nice ... thin, bad fit on the axle... the cheapest possible stamping with old worn dies... is the bmsbattery one any better? Are any of the usual suspects making decent ones?

The axle is is in the middle of the drop-out because it's one of those really cheap bikes. With the derailleur fully home on the other side, the axle has to be half-way up the slot for the wheel to be straight.

The BMSBattery torque arms are excellent. You can't drill them with a HSS drill, you need a 5% cobalt drill as a minimum. They do two sizes: 12 x 10mm and 14 x 10mm. For Bafang motors like this one, you need 12 x 10mm, which are a perfect fit like the Bafang anti-rotation washers.

 

[Beagle123]

The axle is is in the middle of the drop-out because it's one of those really cheap bikes. With the derailleur fully home on the other side, the axle has to be half-way up the slot for the wheel to be straight.

That's exactly right. I can't believe you knew that!

Those torque arms look excellent. The setup you have looks very good, but I might separate the two pieces, and only use the part that goes over the axle. I'd use the hole in it to bolt directly to the frame. On my bike I have a nice flat surface to bolt to. I don't think it would work on your bike.

While I have you're attention, I'd like to get your opion on my current plan for my first model of ebike. Right now I'm thinking of building my bikes with the following components. Let me know what you think:

Battery:
48v, 10ah. This is what I have so far because its the only battery that is easy to install, and looks professional. I'd like to do more, but its very difficult to produce a polished finished product with cells duct-taped to the frame.

I'm about to try this one:

http://elifebike.com/peng/iview.asp?KeyID=dtpic-2011-1J-9479.18EUD

Motor:
Q100 rear. I'm about to buy this one:

http://elifebike.com/peng/iview.asp?KeyID=dtpic-2011-3Y-12GE.4Q2HX

Is the same very slow wind motor as BMS Battery's 201RPM motor? It says "36v 237RPM" What worries me is that it says its for 16-20inch rims at the bottom of the page. I want a slow wind motor running at 48v in 26 inch rim. If this motor is too small, I can switch to BPM in a slow wind.

Controller:
I hear that the 9 mosfet controller frys the Q100 motor, but I'm going to try a different 9 mosfet controller:

http://elifebike.com/peng/iview.asp?KeyID=dtpic-2012-7Q-P96D.9KNYX

I believe that this one will only output 17amps. I think that't good. They're sold out of the 6 mostfet 48v controller.

How does this set-up sound? Please advise me. I'm frustrated dealing with stupid Chinese companies. All I do is ask questions and get off topic answers. It always smells like B.S. Then I wait for a long time to get any products, and generally I learn nothing.

Please steer me in the right direction. This is painfully slow.

Here are a couple of my other issues:

1) I need a Battery Supplier!!!! Not Ping. Too expensive. I need a solution to mount a good battery onto the bike.
2) Finding spokes. I need 230mm to 323mm spokes for the Q100 motors.

I've decided to build the wheels myself to save shipping and time.

Thanks for all your help!!
Eric
[/size]

 

[-dg]

2) Finding spokes. I need 230mm to 323mm spokes for the Q100 motors.

I've decided to build the wheels myself to save shipping and time.

Good idea, plus you can make better wheels.
For spokes, these from Danscomp are about as good as it gets and amazingly cheap. Sun CR-18 or Alex DM-24 rims and a spoke calculator will have you all set.
ps: could you please stop using such huge fonts, it makes it hard to read.

 

[d8veh]

It seems to me that you've got a bit of a mismatch between your components. At 48v, you're on the limit at 15 amps, so a 9 FET controller will blow that motor very quickly. 15 amps and 48v is OK for yourself, when you understand not to abuse the motor, but if you want to sell them, you need reliability, which means 36v and 15 amps that the motor's designed for.

Most vendors sell the Q100 in two flavours: 201 rpm and 328 rpm at 36v. The 328 rpm one is only suitable for small wheels unless you're a sporting cyclist that will only use it at high speed. It'll waste a lot of battery and get hot below 15 mph.

You didn't say why you wanted 48v. It'll push the 201 rpm motor's speed up from 15 mph to 20 mph on the road - maybe a bit more for a light rider.

Those battery racks look ugly to me. I prefer this one that has a plate that fits to any rack. You can even make your own rack out of 4 pieces of aluminium tube, which would not only be much cheaper, but would look nicer too. It comes in a range of voltages/capacities.

http://www.bmsbattery.com/36v/326-24v-lithium-ion-little-frog-abs-shell-ebike-battery-pack.html

Why not get the whole kit from BMSBattery, which saves a lot of messing about with wheel-building. It's probably cheaper too. You can sell the controller on Ebay and get a nice one with LCD display from Kevin Fang (BTN) if you e-mail him with your requirements. Make sure you ask for one with a wheel speed sensor because many take the speed reading from the motor, which doesn't work with the Q100.

http://b-t-n.by-trade-shows.com/contactinfo.html

Here's a thread about how to make a rack. This method allows you to get the battery as low down and as far forward as possible, so that it doesn't affect the handling. Disk brake bikes are better because you don't have to leave space for the brakes:
http://www.pedelecs.co.uk/forum/electric-bicycles/14308-how-make-rack-battery.html
Here's one mounted to a normal rack:

 

[Beagle123]

Hi dev:

Thanks for the help:

It seems to me that you've got a bit of a mismatch between your components. At 48v, you're on the limit at 15 amps, so a 9 FET controller will blow that motor

I was under the impression that it could handle 17 amps at 48v. Now I'm leaning towards the same setup with the BPM. how does that sound?

You didn't say why you wanted 48v. It'll push the 201 rpm motor's speed up from 15 mph to 20 mph on the road - maybe a bit more for a light rider.

That's exactly what I want. My gut feeling is telling me that taking a slow wind geared motor and running it at 48v with a 20mph top-speed would be a good bike for hills and flat terrain.

Why not get the whole kit from BMSBattery, which saves a lot of messing about with wheel-building. It's probably cheaper too. You can sell the controller on Ebay

I don't much like BMSBattery. I bought a torque sensor from them that is a fraudulent product. It has no hope of working on any bike. I think its really dishonest to sell it.

I just received a cheap Chinese battery today. Its labeled as a 48v 10ah lifepo4. I'm actually very encouraged by it. It arrived at 48v, and it took over 3 hours to charge it up to just over 54v. It was using a 1.8amp charger, so I think its holding juice just fine. Since its charging to 54.4 volts, I assume that it is a 15s lifepo4 battery. Right? I tried to open it, but its all stuck together with epoxy-board so I can't see anything. I intend to do a good test on it later. My biggest challenge is mounting it on the bike, and finding a good solution for building multiple bikes. The rack that came with the battery has two problems:

1) The front of the rack must attach to the seatpost area of the bike, but its a dual suspension bike where the seatpost moves in relation to the back end. If you look at the pictures I'm sure you'll understand:





Your thread about building a rack gave me great hope. I was thinking about making four legs for the mounting plate that holds the battery and attaching them to only the back (white) portion of the frame. I could also attach the controller to the underside of the plate. Whatever I do, it must be saleable:



Also, the frame is made of steel, so if it was easier, I could weld steel to it. Imagine making 10 sets of these pieces and installing all of them. That's the plan. In fact, I'd like your advise on how you'd try to run this business. At this time my plan is:

BPM (Code 13 or 14)
17 amp controller
48v, 10ah lifepo4 battery
Some kind of LCD screen would kick ass

Order spokes and motors from chinese supplier, mount motors in bike's rims.

Somehow mount the battery and controller.

Sell bikes myself.

Anyone have any input?

Thanks,
Eric

 

[d8veh]

My comment about 17 amps and 48v being too high was in relation to the Q100. The BPM can go more than 30 amps. If you don't like BMSBattery, you can get a complete code 10 kit from Greenbikekit.com, which saves wheel-building, but you still have to check and tighten the spokes, and probably dish the wheel. The 350w kit has a 22 amp controller, and the 500w one has 30 amps. It's always difficult to fit a battery to a full suspension bike. I think that with yours you can make a rack that fits to the rear sub-frame, but don't forget that you need an additional diagonal piece to stop it from going backwards/forwards. Alternatively you can use a seat-post mounted rack. This is the one I use because it's steel. Aluminium ones break after some time. Search through your own Ebay for exactly this one with the red cord and the same plastic base. They come from China. You have to cut the ends off the plastic piece to make it flat:
http://www.ebay.co.uk/itm/BIKE-SEAT-POST-BAG-RACK-MOUNT-pannier-light-weight-steel-body-with-plastic-shelf-/400479880187?pt=UK_SportGoods_CyclAcces_RL&hash=item5d3e7603fb

 

[Beagle123]

Hi Y'all:

Here's what's happening. I mounted the battery, and took it for a test ride. It is very slow. On flat ground, I get exactly 16 mph. The good news is that I get 15mph up a 4% hill, This is a BPM Code 14 motor. Shouldn't it be faster?

I'm using a battery that was sold to me as a 48v 10ah Lifepo4 battery, but I'm pretty sure the woman who sold it to me lied. In fact I beleive that its a li-ion battery. The charger says li-ion charger and charges to 54.6v. That's a lipo right?

I'm using the K123 controller. I think that the speed is being limited somehow. I tried a different controller, and its seemed about the same. It seems like the energy just stops at at 16mph. Is it possible that there's some rpm limiting in the motor? Do these results seem right? Is the controller limiting the speed?

According to my calculations, a Bafang BPM Code 14 motor should be about 222 RPMs @ 36v. Therefore at 48v, you should expect around 296 RPMs. My bike is getting about 16mph which is about 205 RPMs. I read that your RPMs on flat ground should be about 80% of your no-load RPMs. If that's true, I should be getting about 236 RPMs, or 18 mph.

How many amps do you think the controller is putting-out? Is it going to damage my 10ah battery?

I have the battery mounted, but I'm not too happy with it. I used the battery's mounting plate as the structure for the back rack, and secured it with two pieces of aluminum. It is solid, but there is so much play between the mounting plate and the battery that it rattles like crazy. It sounds terrible and must be fixed. I'm not sure what tot do about it. The battery must be removable, and the loosely fitting plate on the bottom doesn't grab it in any way:





I'd really like to find good solutions for these problems. I've invested a lot of money in these parts, and I have a rattling "bucket of bolts" that goes 16 mph. Help!

Eric