I made an E-Bike - With Pics

[BillyJ]

I've been meaning to post about this for a while now, using a 15kW 120V controller with a 72V battery and MXUS 3k Turbo motor rated for 3kW continuous. I can comfortably reach about 10kW peak.
Bike weighs about 30kg.

She's.. umm... rapid! haha and range is pretty great!
At 30mph with no pedalling I predict approx. 35-40 miles.
Should get 20-25 miles of "hard riding" but brakes get hot quick as I've got no regen at the moment due to my investigation into a previous failure - details at the bottom.

The rough schematics (these changed a little but I ended up not updating the schematic and moved directly to wiring tables for the connectors):
https://i.ibb.co/d5RSt1Z/EBIKE.jpg

Late stage CAD design with 3D scanned bicycle frame and 3D modelled battery, BMS, controller shelf, controller and contactor.
https://i.ibb.co/PM31FXV/Whats-App-Image-2020-05-14-at-23-50-41.jpg

Ally frame fitting:
https://i.ibb.co/tzNf6TL/Whats-App-Image-2020-05-14-at-23-50-42.jpg

Battery pack post-welding:
For anyone in the know, yes all the cells had their internal resistance measured and matched in similar parallel blocks with the highest IR in the centre of the pack to reduce total heating in the pack - although this was an insignificant difference between parallel blocks. Oh and its 20s6p.
https://i.ibb.co/LNCW45Q/Whats-App-Image-2020-05-14-at-23-50-41-1.jpg

Battery pack with BMS attached:
BMS can handle 300A bursts, I have it programmed to cut at 150A and I have a hard fuse at 125A which has been well matched to the setup so far.
https://i.ibb.co/7Shw2P2/Whats-App-Image-2020-05-14-at-23-50-41-2.jpg

BMS software is pretty good actually:
https://i.ibb.co/pQxMzZ1/BMS.jpg

Custom spoked wheel (by me) to the MXUS 3kW motor. (I learnt to spoke a wheel the same night I made it haha):
https://i.ibb.co/pr0mzTX/Whats-App-Image-2020-05-14-at-23-57-36.jpg

Almost finished product with the carbon side plate removed:
Changes made after this were the dash, wiring finished and big gel saddle.
The battery pack is yellow because it's wrapped in fire proof kevlar fabric.
https://i.ibb.co/Fq5zLxq/Whats-App-Image-2020-05-14-at-23-50-42-1.jpg

Here is the 3D printed dash:
Note, the battery percentage is wrong, that's the only sh*t thing about the BMS software. But I know the percentage roughly based on cell voltage.
https://i.ibb.co/41GkCH4/Dash.jpg

Some fun challenges:
The motor is so wide that I had to angle grind the 3mm ish thick logo plates off the casing so they didn't hit the brake calliper... (the calliper still grinds a little )

Had to make a torque arm to transfer the motor torque from the dropouts (can be seen in above image of the bike side on) and instead into the swingarm of the bicycle. Without this the dropouts would just get ripped apart. There's similar torque in this to my gsxr 1000 according to my dyno print out (of the gsxr)

First and only "big" failure so far was at about 55mph when I lost all power and what had happened was a FET short circuited in one of the phases that required extensive open heart surgery to swap out that complete leg of MOSFETs. Since then it's limited to 30mph for range and reliability but I'll start turning up again soon. The worst outcome of this was that after the failure, the short circuit meant that the motor was cogging (dragging) so badly I couldn't even pedal. The first upgrade was adding a connector to disconnect the motor if this happens again so I can at least pedal.

The front flexes quite a lot under heavy braking and turning... a bit like a CB500 haha. I can't do too much about that... meh.

Regarding legality, it can be turned down a lot.

Feel free to ask questions.
____________________
Had: '06 CBR125R + '01 GSF600 + '07 SPRINT ST 1050 + '80 CB250 RSA + '93 Ducati 900SS
Have: '13 GSXR-1000 + '01 CB500S
"The aryan confuser"

[Easy-X]

Impressive, I build one with a 1.5kW rear hub motor similar to yours. Schwalbe tyres FTW I see...

Mine only cruised to about 30, max 35 on the flat - nothing dramatic - but the torque still scared the shit out of me!

My tips: oversized disks, hydraulic brakes. BIG difference Also, what sort of throttle you running? Bit hard to see from the photos. I found a really nice full-twist throttle from China that was practically invisible:

https://www.ebay.co.uk/itm/Ebike-Throttle-for-bafang-BBS01-BBS02-BBSHD-1000W-BAFANG-Part-Accessories/253940399025

...referring to the chunky bit on the end most cheap throttles have.

As to legalities, don't try fooling anyone here. It's a 3kW motor and restricting it to 17.5mph is irrelevant. It's over 250W, no certified throttle, overspec battery and controller: straight to jail, do not pass Go, do not collect £200; if the Police ever bothered you which TBF is unlikely.

I went with a downhill racer frame which was the longest wheelbase I could lay my hands on at the time and - regardless of having less than half the power of your beast - I came to the conclusion that the geometry didn't suit that level of power. Just my personal opinion. So I got a real bike instead

That being said I'd be highly tempted to buy some steel and a tube bender and make up a longer wheelbase custom frame... if I didn't have a million better things to do
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[BillyJ]

Thanks a lot and yeah the tyres are so good! Worth the extra money for the much higher demands they see than pathetic human pedalling haha
Now it's turned down, it cruises super easily at 30 and with very little effort tops out at 40.

It's got hydraulic brakes and I went up 20mm on the already decent size discs. I'd go larger if I had the balls to stack 2 disc spacers on top of each other.
I originally had a thumb throttle but ended up changing it for a nice hall effect full twist throttle from China. Not dissimilar to what you linked actually and it's a huge upgrade.

[stinkwheel]

I wonder if you could fit a set of speedway leading-links to it? That would eliminate the flex and lengthen the wheelbase. You'd need to add some way of fitting a brake though.

Is there a risk of the tyres slipping on the rim with that much torque? Or are you tubeless? Do they need a rimlock device like they use on trials bikes?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[BillyJ]

[Gazza M]

Is the braking on the rear purely through the hub motor then or do you have mechanical brakes as a back up? I'd imagine that takes a fair bit of tweaking so it doesn try to harvest too much when you roll off the throttle

I wonder if there's a way of mounting a second caliper on the front as well to improve the bite
____________________
Past: '07 YBR125, '00 GPZ500S, '99 ZRX1100, '98 CBR600 track bike, '97 ZX9R
Present: '05 R6 track bike, 140 pit bike

[Riejufixing]

[BillyJ]

[Gazza M]

Fair enough, how much do you actually end up harvesting?
____________________
Past: '07 YBR125, '00 GPZ500S, '99 ZRX1100, '98 CBR600 track bike, '97 ZX9R
Present: '05 R6 track bike, 140 pit bike

[Easy-X]

TBH the regen you get back is pathetic - once you get on one of these things the thought of "energy efficiency" flies completely out the window Way too much fun!

However it does make for a good alternative to wearing out brake pads and discs so well worth having. I did toy with various ways of employing it to simulate ICE-style engine braking but I never managed to perfect it.

As an aside, I can't think of anywhere with eBike regulations where 3kW is legal. I'd be curious if anyone could correct me...

Regarding frames: I know what you mean! The suspension arrangements of most downhill racers zap most of the internal triangle. I was only running 48V but even so I still had to weld up a custom shaped pack to fit the space available.

Here's some mad ideas if you have the yen to do something new:

An electric cruiser: take some inspiration from the beach cruiser style, stretch it out a bit but just drop the pretence of pedals and just leave it 100% electric hence skipping the problem of having a massively long chain. A 20 inch fat tyre on the back, standard 26 or 27.5 on the front. Yes, I'm totally insane, ask around.

An electric trike: single electric hub motor at the back and two wheels for steering up front? Far to easy! How about having the both front wheels with hub motors! Twin throttles - you'd need Jedi skills to control it but it'd be a fast way to A&E!
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[BillyJ]

[BillyJ]

[Easy-X]

Here you go:

https://i.imgur.com/79Lwjar.jpg?1

No pictures of the battery pack in a state of undress but then they all look the same really.

Controller's in the top bag, batteries in the bottom one.
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[RhynoCZ]

[BillyJ]

[sickpup]

[BillyJ]

[Easy-X]

Well this is where we go from motorising a bicycle to making an actual motorbike!

The best home made ebike examples I've seen tend turn out more like e-dirtbikes (geometry wise) than push-bikes.
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[BillyJ]

[Easy-X]

If I ever build another ebike I'll just stick with super-stealth.

Unless you swing for big bucks the largest hub motor I've found is 350W that'll tuck behind the cassette to the point it's barely noticeable. Couple that with a light alloy frame and battery/controller tucked in a toolbag one might manage a respectable 20 to 25 mph without actually looking like an ebike.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[BillyJ]