This is a build thread for my first ebike. My goal for this build was to have an electric vehicle I could safely use for commuting during snowy winters here in Latvia. This bike doesn’t satisfy that goal unfortunately, but I learned a lot and will learn more, so keep reading if you’re interested 
I bought this bike 2nd-hand a year ago for 750€. It used to cost ~1400€ new, but has since fallen in price to around 1000€. Hyde Pro Urban Bike - Cube Bikes
What makes this bike special is that it uses a belt drive, which I really wanted because chains can get stuck, smear your clothes, need constant maintenance (I ride my bike mostly on rainy days), and are loud. This was an excellent choice – the bike uses an internally geared rear hub to switch gears (there’s no other way to switch gearing if you use a belt, unless you really think outside the box ), and the gear switching is nearly INSTANT. It’s so fun to ride around in a high gear, stop at a red light and drop down to a low gear and then take off faster than anyone else, and switch back higher right after.
Belt drive requires a bike frame that you can open up to route the belt through, but IMO it’s a huge improvement over chains, and definitely the future. I had my belt snap over winter – turns out whoever I bought the bike from had replaced the belt for one not meant for winter temperatures 
100€ replacement later, I haven’t had an issue since. (Well, I did have my gear hub sometimes skip teeth, but turns out my gear shifter line wasn’t tensioned properly. Read the manual, adjusted, no longer an issue.)
Oh, also this bike came with pretty fat tires (3.75"), and to my surprise this doesn’t make the bike noticeably slower or harder to ride. In fact, the opposite – it eats up bumps and uneven terrain so well I can go fast on this bike no matter the ground surface 
Here’s a video of me riding on a cobblestone road in Riga that’s usually hell on anything else
As fun as the bike was, getting sweaty from cruising at 30km/h wasn’t ideal. Especially if you have a train to catch or there’s nasty headwind. 
My plan was to electrify the bike by getting a front hub motor, and keeping the rear as is. I was hoping this would give me:
- 2 wheel drive for winter
- Great acceleration from pedaling in low gear, with a high top speed thanks to the motor
- Low maintenance, because hub motor
- Easy upgrade experience
My smallest esk8 uses a 750W hub motor, and I wanted something slightly more powerful, so I got a 1500W ebike hub kit from aliexpress. https://www.aliexpress.com/item/1005004066087556.html?spm=a2g0o.order_list.order_list_main.46.36a71802qKmCGL
Turns out that ebike hub motors are severely under-rated (or maybe appropriately rated for long distance continuous riding 
) but the 1500W hub motor that arrived is not only way heavier than I was expecting (like a solid 4-6kg), but also way more powerful than I expected 
With a 12s battery and a 29" tire, I get a loaded top speed of 60km/h, and way too much acceleration for a front wheel drive – I lose traction if I push it to the max, no matter the speed 
I’m getting ahead of myself here. Step no. 2 was installing the kit. I knew I wouldn’t like the included twist throttle, so I purchased a nice thumb throttle instead, like rentable scooters have:
https://www.aliexpress.com/item/1005005288026353.html?spm=a2g0o.order_list.order_list_main.41.36a71802qKmCGL
I’m very pleased with this throttle, I give it two thumbs up 
It was plug-and-play with the included ESC with my hub kit.
I was expecting the included ESC to be crap (like how the rentable escooters are jittery), but it’s surprisingly fine! Sure, it’s really large compared to a vesc, but it comes with a screen you can attach to your handle bars to see your speed and battery level
The largest downside to the ESC is that it has no brakes! The included brake levers are meant to replace your existing brake levers with cables, and they just send a signal to the ESC to cut power 
One of them was so bad it was sending the signal even when open, so the ESC just wouldn’t work with it connected lol. My bike uses hydraulic brakes anyway, so I couldn’t use them. I also didn’t try the pedal assist parts because I have no idea how they’re supposed to work.
Speaking of brakes, here’s another downside to the large hub motor I bought – my fork is not wide enough to accomodate both the hub, and a disk brake 
So I only have rear brakes for now, which isn’t ideal… I will buy an electronic brake lever and switch to Vesc to fix this issue later on.
One thing I had forgotten to buy was a torque arm for the hub motor.
Most bike frames aren’t meant for a lot of torque on the very end of the fork arms, so the torque arm is supposed to shift that load further up the fork so that the lever effect would lessen the force. Since I didn’t have one I decided to go easy on my bike, but after a single accidental burn-out and subsequent regaining of traction, my front wheel jumped out of the fork and bent the shit out of it
I put the fork of the bike in a vice and bent them back straight lol
All of the readily available torque arms looked way too weak for the power of my hub, so I set out to design my own part for this purpose. I decided to use the threaded M5 holes visible on the fork, and designed a laser-cut piece in CAD for the job.
rasejums.pdf (78.4 KB)
torque-arm.dxf (33.0 KB)
torque-arm-cnc.dxf (23.7 KB)
I first checked if it would fit with a 3d-print by a friend:
I’m making the files available here if anyone else wants to use them for this bike, but if I were to redo this I would slightly decrease the width of the hub motor hole. I ordered these parts from xometry.eu out of 6mm thick 6082 aluminum in black (don’t know shit about materials but that’s what Sabre Dynamics uses for his motor mounts so I knew it’d be safe lol), and the hole came out to 10.2mm, which of course resulted in the hub motor having play. I assembled the mounts with some nickel strip on the sides, but I’m not sure if that will hold long-term.
Annoyingly, my bike fork has a weird lip around where the nuts usually go, which with this new 14mm axle is impossible to find a washer to go around. So I had to drill holes in some washers and then angle-grind them to the correct shape
Final assembly looks something like this:
The kit came with a hang-on pouch for the ESC, and I just hung a small backpack over the frame that’s housing my 12s4p P42A flexipack battery 
I had to remove my front mud guard until I can drill some holes in the torque arms to re-attach it. On the rear mudguard I have a go-pro claw mount and a shredlight holder
That’s it for now! Currently getting my rear brakes replaced because they were leaking and ruined the disk (god I fucking hate hydraulic brakes they’re so hard to service), and once I research how to use two ADC input methods with vesc I will order a brake lever and switch to a vesc so that I have front regen braking.
I’m currently broke, so I can’t do much more, but the long-term plan is to replace the hub motor with a much smaller and lighter one, and transfer this hub to a new bike frame but in the rear, where it can actually get enough traction to be used to its full potential. The front wheel drive works really bad in wet conditions, so I expect it to be useless once winter comes. Also I might buy a Megan so that I can log my rides and see my speed on the vesc based system. Also also I want to build a small battery inside of a water bottle for a stealth look. The backpack not only looks ridiculous, but it gets in the way of pedaling and is starting to tear
(Although it still was pretty jerky to control. Not sure if that’s due to vibrations in handlebars being inevitable, or if it’s the chinese ESC)
