Rear frame, shock- and motor mount

So, it’s been a while since I updated the project but it’s been a slow progress.

Started by building a mockup for the subframe to test fitment and how it’d look on the frame.

I’m pretty happy with how the mockup looks and fits on the frame, and it seems to be sturdy enough and kind of not too heavy (this isn’t going to be a super light-weight bike anyhow) so, on we go.

After having upgraded the CNC plasma with a better Z-axis it’s good to cut steel sheet with pretty good precision, so I cut the brackets needed for making all the subframe parts from 2mm steel sheet.

The result is pretty awesome for a low-cost DIY contraption..

After a little bit of polishing with the grinder the final result is more than good enough.

Unfortunately the 20×20 square tube mounted on the side of the frame interfere with the rear shock, the way I were planning on mounting it so I needed to come up with a new bracket.

I milled the rear mount/cover for the motor from 13mm aluminium and secured it to the frame.
Then I made a bracket from 20mm aluminium to support the motor mounts and double as the lower mount for the rear shock.
Bolting it all together with M8 bolts, adding a bolt in the lower “ear mount” on the motor too, everything sits solidly in place.

So I cut a couple of “ears” from 3mm steel sheet and welded the upper shock mount onto the frame. Now the stance of the bike is decided and it feels pretty OK.

The motor/shock mount is easily removed from the bike with just 9 M8 bolts. This is great for service and painting later on. If I may say so myself it looks frekkin’ awesome! 😀

Making the subframe

I decided to make the subframe from 20×20 square tubing as it’s strong enough, not too heavy, cheap and easy to get.

I started with printing paper templates from the CAD drawing and cut tubing to size..
I drilled the holes for the mounting screws where needed in the subframe and now had enough parts for 2 complete setups.
Brackets and frame tubing for the 3 subframe sides needed on top of the mockup I’ve got on the bike already.

When this was done I just had to quickly weld everything together, drill and tap the mounting holes on the frame and make the joining parts for the subfrtame. The subframe goes under the bottom of the frame to be able to fit the footpegs.

Now I can fiddle with the bike “bicycle style”, putting it upside down on the workbench. This makes it a lot easier to fiddle with the motor mount and chain tensioner and so on. 🙂
It looks OK and feels OK to sit on too.

Battery and seat

So, that’s about where we are for now. What’s left is a few fairings, the seat, battery and electrics.. (And the brakes of course)

I made a quick CAD of a seat to see what it’d be like. I’m printing the seat core from PETG plastic and the seat cover from TPU. Experimenting a bit with getting the cover cushioning enough so we’ll see where we end up.

While the 3D-printer is making seat parts I’m finishing up the battery.

Since this battery will have to push north of 200A I’m building it as a copper/nickel sandwich. The configuration is 20s10p, ie 72V nominal. The cells I’m using are Samsung 30T, 3Ah capable of a continuous 35A. The BMS will be a 300A ANT BMS with bluetooth capability. In the picture you can see my new kWeld setup with kCap ultra capacitors. It works flawlessly and gives much more consistant welds than my car-battery setup did. Super happy with this.
To fit the pack in the box on the frame I’m making it fold, so at the moment I’m welding the outer sides and soldering the BMS wires to it. It’s going to be a tight fit but if it gets too wide I’ll just make new brackets and covers for the frame box, so that’s going to be alright.

Well, that’s all for now. To be continued.

Milling and more prototyping

So, since recovery from the fatigue syndrome is super slow so will updates on the project be. That’s just due to most of my afternoons being spent resting and trying to get the brain to recover. But some progress has been made lately, both recovery- and project wise.

I’ve iterated the motor mounting plate design a bunch of versions and am pretty happy with it. Time to make some proper parts.

After some CAM-work in Fusion360 I cut some sheet aluminium and got to milling.

The mill really makes a mess throwing shavings everywhere, but since I built the enclosure at least it doesn’t fill the entire workshop with metal shavings. 🙂

The result when milling aluminium is pretty amazing. This part looks even better IRL than in the pictures and being made from 13mm thick plate it’s super sturdy!

Bolting it down to the frame and mounting the motor everything fits super snugly and I’m starting to question the decision to make a mounting plate on the rear side of the motor too since the motor seems rock solid as it sits now. Buuut, it’s better to make it to tough so we’ll make one just for the fun of it.

Test fitting the chain again with the proper motor mount. I’ll have to make one last prototype of the rear sprocket adapter but now I get proper clearance to both the wheel and the frame so the next adapter is just to get the chainline straight. Right now I’ve got the largest sprocket I’ll use mounted to make sure the chain doesn’t strike the frame in the worst case scenario.

I’ve been getting parts for the second bike aswell. I’m going to build it up to use as a template for checking the geometry so as not to mess anything up when customizing the bike. It’s a chinese clone frame so the geometry probably isn’t perfect to begin with but it’s good to at least know what I’ve changed when re-designing it.

Winter is coming and right now the garage/workshop is a mess with all the projects and stuff that needs storing and protecting from the cold. It’s a bit annoying trying to get stuff done in there but it is what it is. I’ve got to move stuff out when using the plasma cutter that I need for the coming project of making a seat and upper shock mounts..

So, what’s next?

Since footpegs seem utterly expensive I’ve started mocking up custom footpegs for the bikes. I yet have not decided on how and where they should mount to the bike but I know I don’t want them sitting on the swing as the original pedals were mounted on the bomber frame.

The 21700 cells have arrived so I’m looking at making the batteries for the bikes. It’s going to be a 20s10p pack made from Samsung 30T cells at 3000mAh and 35A.

For the first time ever the build is not restricted by the available space in the frame as the bomber box would fit a HUGE pack if filling it up. I’ve decided to go with 200 cells per pack due to cost and weight. This pack is going to be around 14kg just in cells so it’s going to be heavy enough as it is.

72v nominal at 30Ah yields about 2,2kWh which should let us have fun for at least 100km at a time I hope, of course depending on how we ride. =)

I’m using the same method of building the packs as I do on regular bike packs but as with the avant battery this is going to be a CU sandwich type pack as to be able to deliver 300A of peak current..

Here I’m printing the cell frames, three at a time, on my “Stoorn v2”-printer. The next step in the battery process is making cell spacers, measuring the voltage on the cells and starting to put the cells into the pack before welding.

I’ve ordered a pair of ANT 300A BMSes as I’ve used them on all my avant packs and am super happy with the way they work. I’m looking at getting some 10A+ 72v battery chargers to charge the packs in a reasonable amount of time but we’ll see what we end up using.

This is where the CAD is currently at. I’ve printed the first iteration of the back plate and am going to fit that on the bike today as I’m milling the adapters for the rear wheel.

I’m trying to make shorter and more frequent updates but as  it is now the project stands still for huge amounts of time while I CAD and design and print stuff, and then I’m making progress that shows in a few days.. so I’m doing my best to keep everything updated.

Thanks for reading and if you’ve got questions or comments please post a comment on here or reach out on facebook, instagram or discord.

To be continued..

Mockup and motor mount

Having done the mockup for the wheels and mounted the brake rotors and made a mockup for the rear sprocket adapter the next step is mounting the motor.

Since the frame is designed to fit a hub motor and we’re going to use mid-drive motors we need to figure out a good way to mount the motor on the frame. I’ve considered quite a few different positions for the motor but they all have drawbacks. I decided the best solution is to make a motor mount right in front of the rear wheel, making the shortest possible chain line while still keeping the motor as close to the pivot as possible as to limit the unsprung mass momentum of the bike. The tricky part is that this is where the rear shock sits.. So I started by mounting the 200mm shock I’ve got and made the bike sit in the fully extended position on the bench. I then removed the shock, cut the lower shock mounts off and did some measuring.. The CAD turned out like this.

There is going to be a bracket on the left side of the motor too but as of now I’m not sure wether to simply make a motor/shock bracket or to make a new custom endcap for the motor. The right bracket prototype is being printed right now and I’ll use that to check more clearances and get a better feel for the solution. In the CAD I’ve moved the shock all the way to the right to limit the forces on the M8 bolt that holds the shock but where it’s going to go is not yet decided. The upper mount might screw right into the frame or I’ll make it a part of the seat.

I’m going to try to make this modification without welding anything to the frame so it’ll be easier to reproduce if anyone else wants to build a similar “bike”.


New project yet again

Winter is coming and last winter me and the kid agreed on needing fatbikes to ride on the snow..
Of course they’d need powerful motors enough to propel them through the snow and not bog down even when hitting deeper pockets of powder. At first I planned on building my own frames, but as summer came and went and I didn’t have time to get going I decided to get a test frame to start building on to see if our planned setup would pan out..

So, this is what I got:

It’s a chinese clone of a “Stealth bomber” type frame, made entirely from 2mm steel, making it both heavy (20+kg) and sturdy. We’ve got 20″ fatbike wheels on there and personally I think it looks sick. 🙂
The rear suspension I just stole from another bike we’ve previously built and gutted, and the front suspension is a 190mm travel air-sprung fork made 100% from chinesium, but it still seems of rather OK quality.

To get enough power to have fun on these we’re going to use LightningRods BigBlock motors, good for somewhere in the vincinity of 14kW. We’re going to build a couple of hefty 72v battery packs with at least 30Ah capacity and using either ASI BAC2000 or BAC4000 motor controllers to translate the battery DC current to pure joy on the rear wheel.

And yeah, there probably won’t be any reason to put pedals on a bike like this, so we won’t. Footpegs’ll have to do. Since this frame is originally built for hub motors and we’re not using that there are modifications to be made. We’re probably going to fit the motor right where the rear suspension sits right now and move the suspension upwards. A single stage 219 chain reduction will translate the power from the motor shaft to the rear hub. Then we’re building motorcycle style seats to go on the bikes too, some kind of twist throttle, hydraulic brakes, probably have to make my own studded wheels, lights (since it’s mostly dark in the winter) and possibly a kickstand..

Well, that’s the plan. We’ll see how it works out and if we get to ride it this winter. As it sits now the frame, wheels and suspension is in place. I’ve got the motors and controllers but no batteries or other electronics needed. Next week I should get the chain and prockets to be able to start manufacturing adapters to mount stuff where it’s not intended to go and I’ll post updates whenever I get around to it.
First I’ll need to do some modifications to the CNC plasmacutter though to be able to precision cut the parts I need for this project, so that’s next..

Summer, injuries and battery build

So, early this summer season I did something really stupid. I replaced the brake pads on my ebike and took it out for a test.. Riding 50m on the street outside our house being a little bit too tired. The bike was in second gear, I thought it was in third so when I pushed the throttle it wheelied.. a little too much.. Tired as I was I slammed the brakes.. both of them.. so when the front wheel hit the ground it was locked sending me over the bars. Never let go so when the neighbor found me in the ditch I had scratches on the outsides of my hands, my elbow was bleeding badly and I had hit my head pretty bad which knocked me out for a bit. Since I was just going to test the brakes I was not wearing a helmet.. :/
When I regained consciousness I was pretty out of it and after talking to my brother a bit asking the same question over and over he sent me off to the ER. A few stitches, a couple of shots and a complete brain scan later I got to go home with orders to REST.. which of course I did not.

My daughter turned 15 this summer and she got an electric moped for her birthday. Since the bike can fit two batteries I of course had to build one from cells I’ve reclaimed from old scrap ebike batteries..

These are Samsung 30T 3000mAh 21700 cells, good for 35A a piece.

Since the moped and charger says 60V I built this 16s10p pack which would fit the battery compartment in the moped easily.. but then I checked the voltage of the charger and realized it’s a 17s system.. :/ So, I had to put an extra 10s cell on top of the pack making the fit pretty tight, but it still works.

I’ve made the pack in such a way that there’s a SuperSoco connector connected to the 60A BMS and I’ve got 2 XT90 connectors that bypasses the BMS so that I can use the same pack on my future LightningRods BB builds..

The problem is that the SuperSoco uses a serial connection to talk to the battery to display the correct charge state and such which makes this pack show 5% charge even when fully charged.. I’ve ordered a connector that should solve that problem, still waiting to test it.

So.. since I didn’t rest enough after the head injury it kind of never got better. I’ve now been diagnosed with ‘fatigue’, when the brain kind of gets overloaded way too easily. This can happen after a serious head trauma I’ve been told, so I need to let the brain rest A LOT for some time to come. This totally sucks. I have not been able to ride my bike this summer as my brain has not been able to keep up with offroad riding..

In order to be able to get some 2-wheel action me and my wife got one of these each.. not as quick or agile as the Swoop, but it’s super cozy and quite fun to glide around on!

So, it’s been quite a boring summer due to me not wearing a helmet and having a bit of bad luck.. So, if you’re reading this – take it from me.. wearing a helmet when riding is a super good idea, like EVERY time!

Keep safe – have fun. I’ll soon have more fun projects to share!

Running the Evant, frying the controller and finishing up with replacement

So, yes, this happened.. :/

After running the evant for two charges the controller died. It starts, I can connect to it using the USB dongle but as soon as I give throttle input I get an overcurrent error.

Measuring the phases it turns out that one phase is shorted to B-, typical mosfet failure. QSmotor, that I bought the motor and controller from, was reluctant to send me a new controller even though they state there’s a 1year and 3 month warranty period. Somehow they say I damaged the controller but it’s virtually impossible to damage the controller in this way except when assembling it. In the end they offered for me to send the controller back to be repaired, or pay half the price for a new controller.. I chose to send it back, which it turned out was not a viable option at all.. so..
The problem with buying a new controller at half price is that Shanghai is shut down due to Covid and the factory is closed.. so QS couldn’t really tell me when I could get a new controller, so the Evant project halted..


I’ve already started planning my next project. It’s going to be a couple of awesome dirtbike replacements.. powerful LightningRod bigblock motors and matching ASI BAC controllers. More on this later. The thing is, I’ve already bought and got the motors and controllers. So.. I started out connecting my 50A VESC to the QSmotor, just to try it out, and sure – it runs. Wierd that the 800A APT96800 controller got damaged from pushing the same amount of power that a 50A VESC can handle.. well well..

For my build I’m going to use the ASI BAC4000 controller. It can handle 400+ phase amps but is limited to 72V max nominal voltage on the batteries. Since I’ve already built the 48V packs that’s going to be utilized in future projects as well, I’m running the Evant on two 48V packs in parallell yielding 60Ah and 2,9kWh. After discussing the matter with mr HV on the HV discord I connected the BAC4000 to the QSmotor and made connectors to precharge and connect the two packs in parallell.

One problem with this setup is that the QS motor uses an encoder to keep track of the rotor position while the ASI BAC only supports hall sensors.
But it turns out the BAC4000 actually handles the motor better in sensorless mode than the APT96800 did using the encoder. 😀
With the APT the motor sometimes stalled, loosing sync, requiring me to turn the machine off and on again for it to regain sync. The BAC4000 hasn’t lost sync once during the hours of use I’ve put it through.

Well, now that the machine runs again it’s time to finish the project. Until now I’ve been driving the Evant with an android tablet in one hand keeping track of the battery status..

The ANT BMS is super with it’s bluetooth connection and app showing all the data you need, but it’s a bit cumbersome driving around holding a tablet all the time.

I got a display that connects to the BMS in the battery..

Printed a sealed backside and TPU gaskets for it..

And viola, the last piece of the conversion is in place! The display shows the voltage of the battery, the temperature of all four temp sensors in the pack, the highest and lowest cell voltages and the current draw. Since the display connects to one BMS in one of the two batteries the actual current going to the controller is actually double what the display shows though. But now I can keep track of the battery status while driving the machine with two hands!

Today I’ve been moving heavy wet snow from our lawn just to test the Evant out. Turns out I can drive it for a little more than 50 minutes on a full charge..

.. and then it’s time for charging. I got two of these Eltek Flatpack 1500 from a friend and they’re able to push a little more than 30A each into the packs.
Unfortunately one of them had a problem with the voltage regulation and died after charging one pack but with these chargers I can charge one set of batteries in approx 45 minutes. This means that with 2 sets of batteries I should be able to run the machine back to back assuming the motor or controller doesn’t overheat.

So now the build is more or less complete.

I’ve got a few panels to remount that I need to repair first but the machine is definitely ready for use again.

Testing the limits of the battery I ran out of juice in the middle of the driveway..

So I had to get the charger and charge it for 10 minutes to be able to drive it back into the garage. =)

When stuff goes sideways like this it truly helps having good people to turn to. The Evant is running again thanks to the awesome help from Captain Codswallop and mr HV on the HV discord. They helped me tune the BAC4000 for my setup and have been super helpful in making the right decisions and making a wireloom that fits my needs. If you want to build a high power ebike or just make any kind of electric conversion I really recommend joining the High Voltage Light Electric Vehicles discord server.
Also, check out the HV channel on youtube:

Well, that’s that. I’ll post further updates if the controller or motor fails, but for now this project is more or less finished! Hope you’ve found it interesting!

Making the puzzle fit

Started yesterdays work with welding the new controller mount. I decided that it was better to use the existing mounting holes in the motor than to build something around the motor, especially since fitting the battery packs and all leaves very little space around the motor. So I made a bracket that mounts on top of the motor. To fit the M12x1.5 screws I had to mill the heads down on them to be low profile enough to not protrude from the mounting holes.

This mounts rigidly to the motor and with the threaded M6 holes for the controller to mount to everything is snugly and firmly in place.

One advantage to mounting the controller like this is that I can shorten the phase cables quite a lot leading to less losses.. even though the cables are thick enough to withstand all the current the evant should need in the future – less is still more in this case.

Time for the next piece of the puzzle. Since I don’t have all the parameters for the plasma cutter perfectly dialed in yet there is quite some slag buildup on the parts, requiring some grinding and sanding to get them ready for welding..

This is where the battery box is going to sit that’ll house one of the two battery packs in the evant..

.. and this is what it’ll look like from behind. Quite awesome if you ask me.. Still everything needs primer and paint so the warning symbol won’t be as visible, but I’ll try to remedy that somehow..

And this is how the battery sits inside the machine..

I want the pack to sit as far forward as possible to make sure it gets as little abuse as possible from the wheel and whatever debris that might throw at it. I’m going to make a side plate for the battery compartent to protect it further..

The second battery pack is going to go the other way in the machine, sitting as far forward as possible in front of the motor.

Something like that. I’ll add padding to the cover to push the packs firmly in place and to cushion it somewhat – even though the batteries themselves should be able to withstand quite some abuse.. (hopefully)

The only problem now is that the packs actually won’t fit under the “hood” – which is also the mount for the seat, so..

Getting the grinder out and squaring up the problematic part. I just love working with steel, it’s such a forgiving material. If something’s wrong, just cut it up, make a new part and weld it all together, and it’s strong as ever! Add some paint and it looks like new..

So with that modification the battery fits in the machine. Now it’s just a matter of making the pieces I need to cover all holes I’ve made and welding it all together.. After that I need to take care of the electrical wiring, adding the 12V DC-DC converter and installing the BMS displays (whenever I get those from China).. So, quite a lot more to do but the hardest part is done I guess..

So far it’s been a super easy and super fun project.. Let’s just hope it works when all is complete.