Final assembly and test ride

So, it’s been a while since I last posted and it’s been a lot going on. I have had to rebuild the battery for my Radon Swoop which has taken quite some time with measuring all cells and cleaning everything up for re-use but there’s been a bit of progress on the RunBike project too.

So, this kind of is where we left things off last time.
To be able to fit the brakes on the 203mm discs I had to make some adapters. The first version I 3D-printed, until I got it all right and then I made it from aluminium.
I have come up with a way to mount the battery pack which is a bit cumbersome to get in and out of the frame – but once it’s in there it really doesn’t have to come out..
The cockpit of the bike is super clean, with just the tiny eggrider cluttering things up. There’s the domino full twist throttle on the right clustered with the front brake and eggrider display. On the left there’s the rear brake, a thumb-throttle mounted the wrong way around for regen braking and an emergency cutout which kills the controller. On the upper triple clamp I also added an ignition key which acts as the master on/off switch for the entire toy.
The controller fits super nice in the frame box. Mounted in the top of the box it’s protected from any water that makes its way inside. I’ve welded all the holes in the box but water always finds its way, so I’ll be adding a drainage to the box at the lowest part too.
The BAC2000 and BAC4000 are super easy to wire, and both use the same harness so upgrading the bikes will be super easy in the future. 🙂

Drilled a 24mm hole, sealed and added the charge connector for the battery.

The battery has 4 pieces of EC5 connectors spreading the load equally over the pack cells, so the controller needs matching 4 connectors to draw current from.
When all is connected this is what it looks like. Just the signal wires needed but those will be the last connectors I install as they’re in the way of the battery.
I printed and added grommets to all cables going into the box. Partially for sealing the holes but also to protect the wires. All grommets are printed from TPU.
The battery is finally installed and the battery box is ready to be closed. Everything will have to come out again for painting later on but first we have to test the bike out to see what modifications we have to make before paint.
So, finally it’s time for the long awaited test ride..

The bike runs super smooth with tons of acceleration and a seemingly high top speed. The spedometer isn’t calibrated yet so I have no idea how fast I’m going and the roads are covered with ice, but it feels nice! The torque makes the motor pull the rear wheel forwards though so I’ll need to add a chain tensioner to secure it in place. I also need to add brake fluid to the rear brake, which is good to have even though the regen braking is awesome! Also, footpegs will be nice to have to be able to ride standing up!

After a bit of riding I had to test the charge inlet out. Everything works as it should and I get a good bluetooth connection to the BMS inside the box.

To be continued with more awesomeness..

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..