Advice Please -Had my old 12 year old Bafang Build back! Spokes/controller/Display?

[bilabonics]

HiView attachment 7

I built a 36v/500w geared hub (I think) rear hub over 10 years when Bafang were the only guys easily available from BMS Battery Onlne.

I sold it after getting a prebuilt Khalkoff mid drive that I never liked tbh and I’ve now had it back!!

Several spokes are broke and I think they are 12g and 190mm long so I will replace these.

I’m astounded at what is now available and so t know which way to proceed.

I ideally want a KT LCD8S, 1500/2000w and 52v.

I’ve give it a clean and it all works as should all be it the wheel is way out of true, the battery is a small lithium ion I think, it’s 36v/11 ah or less wrapped in blue heat shrink.

I have it mounted in a gritty triangle bag with styrofoam bits in it.
The controller is a basic 36/48v u select 48v be disconnected red wires and I don’t think there’s an output for an LCD.
I extended the cables and sat the controller in a rear Top Peak pannier type case that attaches to the seat post.

I only have fitted a pressure sensor and all I have for monitoring battery level is a cheapy voltmeter.

What should I do here guys?

Should I just fix the wheel and run the battery into the ground and then upgrade?

Or should I get a new KT controller and LCD8S combo and fit that set at 36v if that’s possible until I go to 52v?

Sorry for the long diatribe but I’m ew to all the latest gear, there’s even waterproof plug/play plugs now that I like especially the boxed controllers and unplugable motors!

Pics added for some reference, the bike will be rebuilt/cleaned/tuned/bearings cleaned and regreased etc so like new.

Cheers all.

 

[bilabonics]

Looks like I need 12g spokes and 190mm long.

Can anytime confirm this?

Plus do I replace them all and ‘true’ the wheel myself if I purchase a digital spoke tensioner.

Anyone recommend a seller on Ali Express.

Thanks.

 

[Chalo]

You'll melt your reduction gears if you feed that motor 2000W, unless the hall sensors or phase windings burn up first. If you want to flog a motor way past its rating, use a direct drive hub.

12ga spokes are always a mistake for bicycle rims. For best results, even the replacements for broken spokes should be 14ga. Use 2mm washers to keep them from pulling through the hub holes. Likewise use nipple washers to keep the nipple heads from digging into the rim.

Don't buy anything important from AliExpress. Sellers don't have enough accountability there to keep them honest.

 

[bilabonics]

Thanks for the reply.

I will keep it as it is then as it has run for years with the current set up.

Think I had all the gear from BMS Battery.

It’s a 500w controller and geared hub that is 500w. I recall when purchasing it that there where two types with differing windings and it was pure luck if you had the one with higher torque due to differing windings.

So I may as well fix this up and run it until it dies I presume?

Or fix it up and sell all the gear which is only a controller. Thumb throttle. Cheap Voltage LCD and the wheel itself.
I think I also fitted a 10 or 11t ring on the freewheel.
Plus the block battery that I think is 9 or 11Ah not sure how I can find this out?

I can’t believe I fitted x2 torque as to it as well. :x

Is there anything I can do to get better battery monitoring o en am I just wasting money as I KNOW I will get bored of it at its current spec.

Cheers

 

[bilabonics]

By upgrade I mean could I fit a KT36 and LCD8S with the current 36v set up?

I presume you can set the LCD to 36v for better monitoring but can you set the KT36 to 36v or will it run ok at 36v?

I’d so I can just ride it until the battery dies and upgrade wheel and battery as needed.

Cheers

 

[bilabonics]

Ive just manged to log back in to BMS Battery and all my order are on there -the battery is-

--------------------------------------------------------------------------------
Product Quantity Unit price Total price
36V 15Ah Li-Ion Shrink Tube EBike Battery Pack
Reference: BP00064
1 £139.13 £139.13
Subtotal £139.13
Shipping and handling £40.63
Total £179.76
--------------------------------------------------------------------------------
Product Quantity Unit price Total price
KU123 500W 12Mosfets High Speed Controller
2 $23.00 $46.00
Thumb Level Throttle
2 $4.00 $8.00
1 pcs 12G Stainless Steel Spoke with a Brass Nipple - Length of Spoke in millimeter : 210mm
30 $0.20 $6.00
Bafang BPM 36V500W Rear Driving Bike Conversion Kit - RPM : 201
Reference: MT00016
1 $189.00 $189.00
Double Wall Aluminum Alloy Rim - Wheel(rim) : 26"
2 $8.58 $17.16
Subtotal $247.07
Shipping and handling $132.90
Total $379.97
--------------------------------------------------------------------------------------

 

[bilabonics]

Great advice there, I live on a steep hill/mountain so can’t see it lasting plus I’m 100Kg.

It’s my own bike build from years ago and I had a 48v/17Ah battery in it, when I sold it the battery died and new owner fitted a 36v/15Ah.

That’s going to be ‘buzzing’ like mad up my hill even with a run up and me pedalling like crazy!!

I’m also confused by the using smaller spokes on big/heavier wheels? This wheel is way out, it’s been left on the floor flat and stepped on.

I don’t know for any wheelbuilders near me, I did take one to local Halfords (or Halfrauds as it’s known in the U.K.). The old gent was allegedly good at wheel building. A week later nearly all spokes were loose and it was a waste of time.

I’ve been looking at doing it DIY, they even have digital some tension gauges now!

What I tend to find is that spokes continually become loose.

Can I put up with a 36v bike is the question or can my hill!
:lol:

I REALLY want a 52v/colour LCD/brushless motor, I think the double rim MTX wheels are good and have great reviews.

Cheers guys.

 

[Chalo]

12ga spokes are always a mistake for bicycle rims. For best results, even the replacements for broken spokes should be 14ga.

Chalo, can you discuss why you always recommend 14ga versus 12ga for hub motor builds? Do you have a motor power relative to spoke gage correlation you adhere to? For example, for a 5-10K watt hub motor build aka enduro style ebike or emoto, do you still recommend 14 ga...or only for less than 2K watts? Most motorcycles for example which push considerably more power through the rear wheel and even small motorcycles weigh over 200 lbs...most common spoke gauges are 8, 9 and 10ga which vary in spoke thickness from ~3.2mm to 4.0mm.

Torque forces in a wheel get divided by 36 spokes, so they're really not significant to spoke choice. Also, these forces are inversely proportional to the distance between the projected spoke line and the axle centerline, so large diameter hub motors have less torque-related effect on spoke tension than, say, normal low flange pedal bike hubs. So motor torque really isn't a factor.

It's not motor power, but the kind of rim you use that should guide spoke gauge selection. Most bicycle rims that have a spoke tension rating specify between 90 kgf and 140 kgf maximum tension. Use too much tension and the rim can pucker, crack at the holes, or pull nipples through. Motorcycle spokes need motorcycle rims to work correctly, but then the hub flange can be damaged if it's not also motorcycle grade.

To carry riding loads without problems, the spokes must be tight enough that they have enough stretch to follow flexing in the rim without becoming slack when the wheel is loaded. Even a 1.4mm (18ga) spoke is thick enough to carry a bicycle rim's maximum rated tension, but also elastic enough to remain taut in almost all conditions. A 2.7mm (12ga) spoke needs almost four times as much tension to have the same elastic range, but a bicycle rim can't tolerate that kind of tension.

That hotebike.com link doesn't really get at the issues. Riding hard and smashing into things doesn't demand thicker spokes, at all. It demands a stronger rim. Of all the loads placed on an intact wire wheel, the only ones that increase spoke tension very much are side loads on the wheel. Weight and in-plane impacts can cause some spokes' tension to go to zero, but they can't increase tension by much unless the wheel is already broken.

Here's a diagram of the change in spoke tension from a weight load applied at the axle. Note that the reduction in tension on the lower spokes in this example is up to about 15X the increase in tension on the upper spokes:

The thicker the spoke, the more deeply spoke tension will fluctuate under load, because the stiff spoke can't track the changes in the rim's shape.

Bottom line is, the thicker the spoke, the sooner and more often it will go slack when ridden, allowing the nipple to unscrew, the elbow to chafe at the hub hole, and the nipple to chafe at the rim. The result is frequent maintenance to tighten and replace spokes, and a rim that's easier to bend because it lacks support where spokes are loose.

The reason Chinese hub motor wheels have big fat spokes is because people who don't understand how a wire wheel works (most people) think bigger spokes make a stronger wheel. In reality the result is stronger spokes but a weaker wheel.

 

[bilabonics]

Wow. That makes sense and I totally agree with 12G spokes coming loose!

I have seen a tension tool/meter that basically bends the spoke by attaching to 3 points.

Some reviews say they are essential others state you just tighten a spoke until it starts to distort the rim then back off slightly.

I’ll be watching some videos on how to go mine as I need to convert it from a rectangle to a circle.

 

[calab]

Use boiled linseed oil or spoke prep lube or any lube.
Use brand name components Sapim spokes, brand name rims, no no name stuff or generic stuff.
Do proper lacing
Should last a long time if the rider is of average weight, if rider is severely obese, the extra weight will cause problems on a badly laced wheel and it snowballs to failure very quickly.

I have done hundred of miles of a laced hub with 6 broken spokes, the key point for 245lb man is when theres 8 spokes it starts to wobble and my spokes are not even close in any respect. Seems to straighten out when I go faster.

 

[bilabonics]

I have ordered 12G Sapim stainless spokes and 5mm nipples to get me back on the road.

@Ebuilder what do you suggest on mounting components? I only used a triangle bag as that was all that was available back years ago.

Ideally i would like the controller is a controller WP box, and the set up to be all WP plug/play, especially the rear motor cable for when replacing inner tubes etc, but i don't think its capable on a 52v set up as the cable would be too small and the controller would overheat in a box.

My brother has a cheapy Cyclotricty 48v/11Ah/1000W Rear Hub Chinese pre made bike and it's neat, controller is under frame in plastic box, all connections on loom and waterproof plus easily disconnected even the motor but the frame/brakes are awful..

What's your unconventional approach to mounting battery, i've seen things you can add extra mounts etc.

I gave the frame a good clean today, all cables are frayed, bottom bracket is a bit loose/needs grease, breaks definately need bleeding as well but i suppose i can ask on a standard bike forum for help on that?

Thanks guys, can't wait to get back on the road the hill is killing me it's known locally as 'Death Hill'..... :lol:

 

[amberwolf]

Chalo, can you discuss why you always recommend 14ga versus 12ga for hub motor builds? Do you have a motor power relative to spoke gage correlation you adhere to? For example, for a 5-10K watt hub motor build aka enduro style ebike or emoto, do you still recommend 14 ga...or only for less than 2K watts? Most motorcycles for example which push considerably more power through the rear wheel and even small motorcycles weigh over 200 lbs...most common spoke gauges are 8, 9 and 10ga which vary in spoke thickness from ~3.2mm to 4.0mm.

FWIW, my very heavy (400lbs+ plus my nearly 200lbs as rider) SB Cruiser trike uses wheels I built with Sapim 13/14G butted spokes in a radial lacing (no cross possible in this situation) on both rear 20" wheels. I carry up to hundreds of pounds of cargo (or up to a couple of St. Bernard dogs) in the trike (and can pull even more than that in a custom trailer). I don't have spoke problems with it, even when I have had rims damaged by potholes and had to retension them, even with all the sideloading these wheels see in turns and whatnot.

If I were building them again I'd use thinner 14/15G spokes to even better support the loading of the rim.

After my experiences with other motor wheels that came with 12G spokes, and others I built with them before I understood more about spokes, I definitely wouldn't use 12G or larger spokes. (unless I was building using motorcycle rims that are designed for those, but those are a lot heavier as are the tires for them; I'm already using moped tires for their thickness against punctures from road debris, and those are heavy enough).

 

[999zip999]

With the age and miles. Just get the spokes you need even if 12ga.from bms battery as you should only need a few . So buy 10 of them run it. Learn to true a rim. Use a steel front fork as you may need to widen to fit for a truing stand. Get the bounce out first then side to side. Don't sink money in it ride it.
When you have to buy a new 52v 15ah battery and a motor kit next.

 

[999zip999]

Looked at bms battery website they don't look like a deal after remembering there shipping cost.

 

[bilabonics]

With the age and miles. Just get the spokes you need even if 12ga.from bms battery as you should only need a few . So buy 10 of them run it. Learn to true a rim. Use a steel front fork as you may need to widen to fit for a truing stand. Get the bounce out first then side to side. Don't sink money in it ride it.
When you have to buy a new 52v 15ah battery and a motor kit next.

I’ve ordered x10 spokes locally from EBay.
BMS Battery delivery prices are ridiculous!

I did have the battery in ma triangle bag and the controller is a Top Peak rear rack/bag that attached to the seat post. It is now in very poor condition.

Since i now have a smaller battery can I just put the both the battery and controller in the the triangle.
There’s plenty of room.

I’ll ride it until until it dies then get a shark style 48v or 52v with high output battery 30a or 45a with a 2000w induction motor. Not the plastic geared one I have.

The battery bag looks very grubby as well and zips are knackered.

 

[bilabonics]

With the age and miles. Just get the spokes you need even if 12ga.from bms battery as you should only need a few . So buy 10 of them run it. Learn to true a rim. Use a steel front fork as you may need to widen to fit for a truing stand. Get the bounce out first then side to side. Don't sink money in it ride it.
When you have to buy a new 52v 15ah battery and a motor kit next.

Spokes have arrived.

I've looked at a few videos on how to true a rim and it's all specialist gear, i don't have a steel front fork to hand either.

So a truing stand is something that connects to an old front fork i presume?

By the 'bounce' i think mean the altering the circumference/circle so it does not ride up and down...

I'm going to stick them on the rim later and see how good i can get it just on the rear forks with disk/caliper removed.

Is there a cheap 'tool' to do this and a relevant guide?

Thanks

 

[999zip999]

OK I will show you a homemade one weld each wheelstand ki
And a angle grinder it an old bed frame with a center support.

 

[999zip999]

More pics later goin my ranch. No pics of ranch ever. My church. Sacred grounds.

 

[bilabonics]

OK I will show you a homemade one weld each wheelstand 1662508676775585086825.jpg ki
And a angle grinder it an old bed frame with a center support.

That looks brilliant.
I have access to plenty of angle/flat so could easily whip one up.

Is there one I can copy online?
I can see the wheel sits in the rear but from the pic I can’t see how you check the wobble in the wheel (left to right) and the how the height/circumference is measured, I know that’s named the ‘bounce’ feom being mentioned above.

Thanks for helping.