Downhill/jump bike to 5000w hub motor conversion

[user27]

I was casually looking at ebikes after a friend got a 1000w one recently.

I have a pretty decent spec hardtail that I built using a bulletproof nsbikes jump frame a decade ago; I was living near mountains at the time and I didn't want the bounce of full suspension on the way up them; also didn't much care for comfort value I really just wanted to hammer the forks on the way back down. That bike hasn't seen any use for a good while; here's the original parts list:

Fork: Fox 36mm '09 TALAS RC2
Stem: Truvativ Team 1.125 x 75mm (black)
Handlebar: Truvativ Team Riser 31.8 x 680 x 35
Headset: FSA Orbit MX 1.125
Cranks: Truvativ Stylo 3-ring 175mm
Bottom Bracket: Truvativ GXP (included w/Crankset)
Front Brake: Stroker Trail 8"
Rear Brake: Stroker Trail 6"
Tire - Front: Maxxis High Roller 26x2.35 Foldable
Tire - Rear: Maxxis High Roller 26x2.35 Foldable
Tubes: Maxxis Ultralight
Seatpost: Truvativ Team DC x 350mm
Saddle: FL white
Grips: ODI Cross Trainer X 
Cassette: SRAM PG980 11-32
Rear Shifter: Sram X9
Front Shifter: Sram X9
Rear Derailleur: Sram X9
Front Derailleur: XT
Chain: KMC z9000



Given that I had most of the push bike type bits I started leaning towards a DIY build; started getting a shopping list together and with every iteration the wattage got a little higher than the 1000w I started at... Eventually settled on 5,000w, got excited, and ordered a motor for £349 here:

https://www.amazon.co.uk/dp/B07ZVP7YL6/ref=cm_sw_r_cp_apa_glt_i_XAT8T434N20QC21K4Q2R?_encoding=UTF8&psc=1

I have since seen the same for less money on Ali... But this way I had the Amazon buyer protection and it did actually show up.

Now that I'm living in relatively flat North Essex, I'm feeling old in my mid 30's, and full suspension comfort seems like a really good idea.

I ordered this frame just because it ticked all my boxes for a bargain price; £190 with an eBay voucher.

https://www.ebay.co.uk/itm/224524021545

Then this DNM shock, £85

https://www.amazon.co.uk/dp/B08R8NYGCT/ref=cm_sw_r_cp_apa_glt_i_FY1YJH7YQFRRVCBF9V7B?_encoding=UTF8&psc=1

30 MOSFET Greentime controller, £123 with delivery and tax:

https://m.aliexpress.com/item/32961621169.html

Found the guy on here selling pretty high spec 20Ah lipo cells for relatively affordable prices, decided to go for 32 of them in pairs so 16 pairs in series, 59.2v-67.2v since the controller has a low voltage cutoff at 40v it wouldn't really want to be any lower voltage.

This 16s BMS has Bluetooth etc and I ordered it for £45

https://www.ebay.co.uk/itm/165030161142

This throttle and voltage display £9:

https://www.ebay.co.uk/itm/353868797445

Charge port, £2.50

https://www.ebay.co.uk/itm/254180444408

Stem mounted holder for an old phone with Bluetooth to BMS:

https://www.ebay.co.uk/itm/275120241619

Then an 8A charger for £85

https://www.ebay.co.uk/itm/255329580844

Have to swap my nice SRAM cassette out for a crappy freewheel, £23

https://www.amazon.co.uk/dp/B09BNFFK2N/ref=cm_sw_r_cp_apa_glt_i_75E6WBAZ3X672WJNF5XP?_encoding=UTF8&psc=1

My wheels had the wrong number of spokes for the motor and they were going to have to be replaced anyway; I did consider small diameter motorbike tyres or fat bike tyres but they didn't really appeal; I'd much rather it looks like a push bike so I don't get pulled over and/or banned from MTB trails etc... so I ordered white powder coated Halo T2's for £90

https://www.halowheels.com/shop/components/rims/t2-26-rim/

Then had to do the front 20mm through axle for the fix forks to match, another tenner.

So the long and the short of it is I'm into it for a grand plus batteries; which is currently a fair bit less than buying a 5000w ebike I think?

Hopefully enough of you read this with enough knowledge and experience to tell me what mistakes I have made so far and which to avoid going forward?

Thanks for reading

 

[calab]

You do know that sellers will claim anything to get a sale right?

Its all to common for bigger motors to be listed as lower power to get a sale. Some of the bigger motors downgraded and listed as 250w to get scared brits like you to buy. Just saying your a brit, not that your scared, I commend you for standing up and going big. It does go the other way around for people who dont really know what they want but want the most power they can get. Most likely you have a 35h or 45h motor with an inflated price, not a 55h motor more commonly generalized to be 5kw, the others being 3kw and 1.5kw. Its easy to check once you have the motor, even a quick measurement of the flanges you'd know.

https://www.amazon.co.uk/dp/B07ZVP7YL6/ref=cm_sw_r_cp_apa_glt_i_XAT8T434N20QC21K4Q2R?_encoding=UTF8&psc=1
Not that the info can be trusted, with an unknown seller as far as I can tell.
Item weight 12.8 Kilograms
Oh my bad it is listed - still, best measure it when you get the motor. Hopefully you got good lamination thickness, an aluminum innards.
V3 5000W Ebike motor
50H magnet
Damn even a kv is listed - good stuff
KV:9.3KV
Interesting note I hope you paid attention to
Drop out : 147mm
Axle size : 10mm x 16mm

The flanges do look wide, I hope you open it up and measure the laminations, count the laminations and take some pictures. Its always good to get more in depth knowledge on unknown sellers. I never heard of NBPOWER before. 2 pages of search results
https://endless-sphere.com/forums/search.php?keywords=NBPOWER

 

[user27]

Thanks for reply and good info, I did check the spec a bit since I have some minor brushless RC experience to know I should look at kv number.

Also it is here... And I opened it.... But you're wrong about one thing I'm afraid... I still have no idea what I'm looking at!



Got some legal stickers too:



Controller does indeed have at least 30 MOSFETs as listed that I can see and serious heat sinking which does appear to have heat transfer paste.



You're right to mention dropout since I had to machine a quite specific spacer to get the clamping surface out beyond the freewheel as below. Is there any other reason I should be concerned about the dropout? Axle is roughly 200mm long overall.






Do I need a torque arm? (Or arms)? Or just the tabbed washers the motor came with?

Thanks again

 

[user27]

This post seems like good info regarding NB motor seller; also recommendation to do what I'm doing in that it's best to buy a motor alone and get it built locally with a good name brand rim and spokes.

https://endless-sphere.com/forums/viewtopic.php?f=3&t=112206&p=1660970&hilit=NBPOWER#p1660970

Would be interested to know if it's really a 5000w motor based on photo above.

 

[SlowCo]

That will work fine together. :thumb:
By the look of it that motor can take way more peak amps than your controller and battery/BMS are capable at feeding it. If you're worried then search for "Statorade" or "FerroFluid" on this forum to keep the motor cool enough. As you've opened up the motor already, see if there is a temperature sensor in there. If not, put one in. That way you can keep an eye on the heat in the motor with your use.
As you seem to be able to machine stuff, I would consider making a torque plate that fits in the rear swing arm. Or weld a ring and nut at the back of the drop out so you can clamp the drop out together.

 

[user27]

Hooked up some little RC lipo packs in series for testing; but the motor is with the guy who's building wheels etc for me so I can't actually test it yet. Nothing went bang or let the magic smoke out though.




Should have the cells, bus bars, and BMS here next week to start the real 16s 40Ah battery build.

Anybody know what these type of plugs are called? I'd like to get a selection pack of sockets to match so I can just crimp them to my loom.

 

[E-HP]

With the route you've chosen, you will only ever use 2 or 3 gears, maybe only one, so the freewheel is overkill. You could skip the spacers and get a 5 or 6 speed freewheel.

 

[user27]

Which two or three gears? I'm assuming that I'll run the battery flat or blow something up at some point such that I'll want low gears to get the heavy beast back to base.

Then something high geared to actually contribute at 5000w speeds?

Already made the spacer and bought the freewheel so that's definitely what's going on there; I'd have to fit a spacer of the same design, perhaps shorter, to do anything more than a single cog.

 

[E-HP]

Which two or three gears? I'm assuming that I'll run the battery flat or blow something up at some point such that I'll want low gears to get the heavy beast back to base.

Then something high geared to actually contribute at 5000w speeds?

Already made the spacer and bought the freewheel so that's definitely what's going on there; I'd have to fit a spacer of the same design, perhaps shorter, to do anything more than a single cog.

The smallest 2 or 3. With a 30 pound direct drive motor out back, you will never pedal the bike without power. Maybe you'll last 50 yards before you decide it's easier to push it. You're still thinking bicycle, when you've chosen motorcycle. Ride it for a year, and you'll see that the bigger cogs will now see use during your initial testing, and look brand new. You're basically adding more baggage/weight.

 

[user27]

I figured 27kw was motorcycle; 5kw isn't going to lift the front wheel with a fat bloke on the saddle right?

So what size cog do I put on the front?

 

[E-HP]

5kw isn't going to lift the front wheel with a fat bloke on the saddle right?

If you feed it the power it needs, you be on your back the first time you twist the throttle, if you're not ready.

PS. your thread subject is a bait and switch. the conversion sounded interesting, but it isn't a conversion. Got suckered.

 

[user27]

Is that so, where do you draw the line? Presumably the electronics is all conversion stuff so it stopped being a conversion for you when I changed the frame?

Any guesses what those plugs are called so I can stock up?

Thanks

 

[E-HP]

Is that so, where do you draw the line? Presumably the electronics is all conversion stuff so it stopped being a conversion for you when I changed the frame?

Any guesses what those plugs are called so I can stock up?

Thanks

You're salvaging part from an old bike to build a new one.
It' s not like a house, where you tear everything out, and keeping one wall turns it into a remodel instead of new construction.

The white are Molex, the black and JST, the green are bullet, the small yellow are XT60, the big yellow is just a connector junction.

 

[user27]

Fair enough; I figure I'm keeping more than have the components; maybe now that I have had to change the wheels it's a salvage and rebuild situation!

It is my understanding from working with IT stuff that these are molex; square pin into square tube:





...and indeed searching for molex on eBay shows those square pin ones:

https://www.ebay.co.uk/itm/Molex-4-2mm-2-to-24-Pin-Way-Multi-Plug-Connector-Sets-male-Female-Terminal-/283463643697?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

However these plugs and sockets on the controller, including what seems to be standard for the haul, are flat blade type pins?

 

[user27]

Maybe these, although it doesn't say what they are?

http://electricscooterparts.com/whitewiringconnectors.html

I'm going to order these 2.8mm ones below and hope they fit; was hoping there would be a brand name like "molex" or "jst" that would work to search for the correct thing but neither of those show the right thing.

https://www.amazon.co.uk/dp/B07K9PKCVX/ref=cm_sw_r_cp_apa_glt_i_66SCT3E5FH5XKPSHT5EC

 

[E-HP]

Look for Molex spade:

https://ebikes.ca/learn/connectors.html

 

[user27]

Good link! I'll be saving that for future reference! Seems like adding 2.8mm to search finds them.

Cheers

edit:
Confirmed those connectors fit; search for 2.8mm terminals found them.

 

[user27]

Since it seems hard to find; here's the English 16s ant bms manual with wiring diagrams:

View attachment C2071542 ANT16S-ZY .pdf

Required passwords:

View attachment 说明.txt

My one... Still currently lights out no leds, no sound, but no magic smoke released either.