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\\ Ebike [1.0] - 18KW Urban “Super Cruiser” E-Bike \\

Taking it back to the beginning! This is the first ebike I had ever made and it’s a bit over the top. This all started because a few friends at work said they wanted to make their own ebikes and prior to that I wasn’t particularly interested in bikes or ebikes for that matter. I used to love riding bikes as a kid but had for the most part grown out of that. I of course had to out-do my coworkers so I decided to build a pretty crazy ebike for my first one.

I started doing ‘some’ research (but obviously not enough as I’ll get into later) and I was very impressed by the (at the time) powerful motors from Cyclone. I read an article on the 3000W mid drive kit and it was relatively cheap for the power that you got and the reviews were favorable. After I was looking into that I discovered that they even offered a 7500W version and I saw a guy take his mountain bike on the freeway! (!!!) I FOUND THE VIDEO! I knew that I wanted the 7.5KW version so when I went to purchase it I realized that they even made an 18KW version! My god look at the power! I debated for a while because I know even 7.5KW was over the top, and the 18KW was considerably more expensive, but I figured if I was going all out with the 7.5KW version I might as well go all the way, so that’s what I did!

I built this bike long before I ever thought I would ever be creating videos or content so I don’t really have any footage of the bike in action, but I did take a lot of pictures along the build. Maybe it will inspire you on your own builds.

I did learn a lot as one would expect from their first ebike build. What I didn’t realize at the time was that just because your motor can handle a ton of power, it’s a bit meaningless unless your battery can supply that power. I figured a battery is a just a battery, but the battery is as critical of a component as your motor and controller. All of these components need to be balanced to achieve the best performance.

It’s the same as matching your components for a computer, it doesn’t make sense to put an Nvidia RTX 3090 in a system running an Intel Pentium III processor, you’d have a severe bottleneck! You want all of your components to be matched otherwise it’s a bit of a waste as your system is only as powerful as its weakest link, much like a chain. The same goes for ebikes.

I had to get a custom battery pack made and they asked me “how big of a BMS” I didn’t even know what a BMS was, so I just said “standard” and they put a 50A (80A peak) BMS in the battery, also it’s only 25AH and for a very powerful motor you need a battery large enough to offset voltage sag, all of these things I had no idea about when I initially was dreaming up this build. Because of the battery the output is more likely in ‘only’ the 4000-5000W range, which is nowhere near 18KW! But it’s still a ridiculous amount of power for a regular bicycle frame, and although I never did a full speed run (was too scary really) I estimate the top speed to be between 45-50MPH which is plenty fast for a bike.

Another thing I realized is that if you put 18KW through a regular bike chain, it’s going to snap, for that amount of power you most likely would need a motorcycle chain, something strong enough to handle that power. The bike does have gears (7 speed) so I was still able to utilize the gear ratios to adjust for torque or top speed, which is pretty cool, although when you have this much power it’s a bit unnecessary. This is when I learned that hub motors were the way to go for me. There is a lot of debate over which is better, hub motor or mid-drive, and it really just depends on what you’re going for and your specific application. To me, once you get into the higher wattages, the advantages of hub motors starts taking over. It’s direct-drive so there is no chain to break, the axle will handle whatever power you can put through it, they are also simpler.

One more thing I realized is that when you’re going faster on an ebike, having a suspension becomes a necessity. When you’re peddling a regular bicycle you’re only going 20-25mph tops and it’s not fast enough to notice how bad the roads are, but once you start going 30-40mph the bumps in the road become much more harsh and frequent, I knew that for my next build a full suspension was a must.

\\ Parts list: \\

1. The Frame

Made by the company SIKK, this giant steel frame fat tire beach cruiser has cool ‘chopper’ style ape hanger handlebars and a matte black finish. They call it the UFO and I guess it’s because it’s so unique for a cruiser. I wanted a frame that would be strong enough to handle the power and large enough to house all of the components. SIKK UFO Fat Tire 7-Speed Bike

2. The Motor + Controller Kit

Made by the Taiwanese company Cyclone Ebikes, this behemoth of a motor is a 72v (up to 104v??)
18kw Triple chainwheel kit

The controller is a 150A sinewave controller. It looks like they now include an LCD display (my kit did not include it).

3. The Battery

This is where I made my ‘noob mistake’ - I should have bought a much bigger pack with a much higher discharge rate - it’s a 72v 25AH battery with a 50A BMS (80A peak). To utilize the full power of the motor I should have had at least 50AH pack with a 150-200A BMS.

The link to this product is no longer up from the seller, but any 72v 25AH pack would give you a similar experience. The pack I bought did have Panasonic cells.

4. Miscellaneous Other Parts

\\ The Build \\

I was able to find this frame I was looking for semi-local on CraigsList and scored it for about half as much as a brand new one, and it even had an upgraded seat and was in excellent condition.

Acquiring the massive 18KW motor! 24.5LBS!

This was one of the biggest pains of the build! The threads on the bottom bracket were basically welded shut with rust, so after a day or two of frustration, I finally was able to break it free using a tool I made to clamp it and also of course the blowtorch.

Getting a rough estimate on where to place the motor.

Started creating the mounting brackets with some aluminum flat bar and u-bolts to attach them to the frame bars. The motor originally comes with a bottom bracket mount, but to me that was not enough. This shouldn’t allow it to move at all!

Using some (modular) angled steel to create the shelf for the battery.

Making my own brackets to actuate the rear brake light. When you squeeze the brake it releases the switch and the light comes on. Release the brake and it engages the microswitch and turns the light off.

Modding the ammo can battery box. Adding the hall sensor for the LCD voltage display.

Wiring up a custom ‘switchback’ circuit for the turn signals, two relays and a flasher does it. I was going to just buy a circuit that does this but they were too expensive so I built my own. Wiring up the RGB strip lights.

Looking pretty good with the lighting!

All of the major components wired up and ready for a test ride. It runs excellently!

Time to dissasemble and start painting everything blaaaaaack!

After painting now it’s time to reassasemble everything.

Have to go with a custom acrylic dashboard featuring a Nexus 7 Tablet

And it’s finally completed! It came out awesome! You can adjust the LED lighting on the bike through the tablet via the bluetooth controller, so cool! The giant GPS speedometer looks really cool and is functional.

I did learn a ton of this build and it has been the foundation of knowledge for all of my subsequent ebike builds. I had a lot of fun putting it all together and it came out incredible!