Electrical bike, nuggets style...

So I'm building an electric bike...

Sorta like @sailah but different...

I am using regular bike as a starting point. It's way overpowered...

More to come...

A tease...

Ok I'm in!




Sean

Ok,

So I'm using this motor kit:

It's a 3000 watt cyclone motor kit. From here: https://lunacycle.com/cyclone-mid-drive-3000-watt-planetary-kit/
The motor mount itself is shit. We'll cover that...

3000 watts isn't a lot in motorcycle terms, but it's a lot in bike terms.

Roughly the same as having two of these drug fueled fuckers pedal for you, except these dudes can only sustain that output for about a minute...


And bonus, an electric motor will not hit you up for drugs...

Forgot to add...
The motor kit is a mid drive kit, so the motor hangs out by the pedals, and puts power into the bike drive train. So you can pedal along, and use the gears to get the power going at the speed you want. If you are following sailah's build, he's got a hub motor (a big nasty one).

For a mid drive, the motor sprocket has a freewheel, and the main front sprockets also have a freewheel. The motor drives the sprockets, and you can shift gears like normal. This gives you the ability to move the torques around with the speeds and tear up bike components that were never designed for this shit...

"tear up bike components that were never designed for this shit..."

I'm in

Let's do this...

I acquired a nice entry level GT backwoods comp. It was the best deal I could find for a front suspension MTB with hydraulic brakes and mounting points for rack and fenders. All the equivalent bikes were at least $600, with the same level of components. This one ended up being $380, since performance took an additional 15% off for presidents day... (Fuck, it's been that long... )

Here is the victim:




Here was my plan.

Practical mods:

• Rack
• Fenders (This will get ridden in the rain).
• Headlight
• Taillights (I'll use taillight tape to make these red).
• LED Flasher - so I can make the taillights blink.
• Voltage converter so I can get 12V for lights.

E-Bike mods.

• 180MM rotor upgrade for the front brake.
• 52V 14ah Battery from Luna cycle

Original plan was to stiffen the motor mount like so:


I was so excited, I even made little models of the major components...



Once I got the parts, it didn't actually take that long to get to a little shakedown ride...

There were definite issues, but it quickly became clear that I was building a beast*




*for a bicycle. I mean obviously, this is no KTM 1190 or hayabusa or anything like that. But it has way more go than the chassis is meant for.

This kit's not exactly bolt on(I knew this). Notice how the chain tensioner for the motor is. That's not my hack job, that's what comes with the kit. The motor mount that comes with the kit is not strong enough. Even running the bike with no load on the bench, there was significant flex.




This is my proof of concept tensioner prototype.




Works like so:



So, I put the throttle on the bike, and threw the battery and controller into the frame bag that came with the battery. That was good enough to take it for a spin. Power wheelies in the lower gears. Hydraulic disc brakes and a larger front rotor were good to have.

It won't have pedal assist installed, just throttle.

Chain tensioner v.2



So the bike went back on the bench after test riding so I could sort out the controller mount, battery mount, fenders, lights...



The first thing I did was to disassemble the controller in order to add a cycle analyst (fancy e-bike computer) connector and to lose all the extra connectors...


I got rid of the brake, cruise, PAS, and hardwired the 3 speed switch for max speed. I didn't buy the cyclone for low speed!

The bench test was a success. I setup the speedo, and the motor spins the wheel up to 52 MPH unloaded. Not bad.

Nothing bolts on this bike, I even had to make little stay extenders for the rear fender.... And a few other fender mods... Haven't added the front fender yet.

Like where your head is at man. No talk yet of aesthetic, will you be going for a stealth look like the guy on the right, or balls out like the guy on the left?

More like so...

So the motor mount that comes with this motor is a pathetic joke, it has multiple issues.

I held the brake and applied power, in order to test the mount.
1. the mount will flex side to side.
2. the mount twists.
3. under power, the mount is pulled up to the frame, and crushes the rear brake line.
4. the mount falls down when you hit bumps.

I'm not going to use the cheesy giant hoseclamp and zip ties that come with the kit, just too hokey, and the zip ties are guaranteed to fail over time.

This shows how the mount was supposed to work. The thing that looks like a fat black tube is the bottom bracket on the bike frame.



So, I set out to beef up the mount.

I initially planned to do something like this, but I don't think that will help much with the fact that the mount twists under load.



After a lot of head scratching and false starts I laid out some lines and curves on some metal and started cutting.



I'm using 3/8th 7075 plate.

I used some tricks to match the curve to the motor...





Once I got the curves right, I laid out the mount holes. The little blocks you see are what come with the motor. Nowhere close to strong enough.



And drilled them, and test fit them...



Then I added the holes for the mount brackets...



Then I made up a third plate from 1/4 plate. Then I test fit the mount again. Here you can see the weak and cheesy mount blocks that my plates are replacing. The two 3/8 plates, and one 1/4 plate were not quite thick enough, so I had to add a shim plate from 0.030" sheet. It already feels much stiffer.



The new motor mounts are close to complete, and they look like this.



I asked a guy I work with to bend me a small bracket from 0.090" plate. It will bolt onto my mounts, and then bolt to the black brackets. Then the motor will be highly resistant to twisting with respect to the bottom bracket. Here it is mocked up.



I'll drill and tap the mount plates from this direction.

Drilled and tapped to tie the motor mount to the bottom bracket mount.


And I added these braces.


Another angle...


This whole thing is put together with a collection of random fasteners, so I will have to buy the correct fasteners.
Here it is mounted on the bike. I had to change all the fasteners on the sprocket side to low head socket screws since the hex heads intererfered with the sprocket and the chain.


Once everything spun well without power, I turned it on and throttled up. Previously, the mount would twist just spinning the wheel under no load. It doesn't do that anymore. I used the brake to hold the wheel, and applied power. The motor twists... WTF?!

I look at it some more. It's not the mount. As it goes when you strengthen one thing, you find the next weak thing. It turns out the mount does not twist anymore, it's actually twisting the bike frame. The cycle analyst says that I put 100 amps into the motor to do this....

The good news is that the mount is strong enough. I'll see how long the frame holds up...

POWAH!!!!!!!

I've got to add a bracket to tie the motor into the down tube so that the motor won't rotate down when I hit bumps, and so the motor won't rotate up when it pulls on the chain. Once that is built, I'll finish all the motor mount parts, and be done with the motor install.

Absolutely loving this! Plan on doing something very similar to a fat bike after I move in a few weeks.

...still more powerful and lighter weight than a CRF250L Rally...

Nice fab work.

Have you actually tried doing this with your legs? Bicycle upright, sit on it, hold the back brake on hard, push down hard on one pedal. See how much it moves? I wouldn't worry too much about the frame, you'll not be putting that much torque into it that often.

"tear up bike components that were never designed for this shit..."

"it's actually twisting the bike frame"

I'm in times 2

I've ridden the CRF250L, so I know what you mean. Why the fuck couldn't honda at least but the bigger motor from the CBR300 into it?

Thanks for the fab work comment, I'm a lowly hacker compared to most guys here, but I get better as I go...

I'm not a worrier...


I made this white plastic block to prevent the motor rotating upward under power.


And I made this strap to prevent the motor rotating down when hitting bumps. The strap looks nice, and works well. A bitch to bolt on though...


I've also built my controller mount.


Holes...


I replaced the rack bracket with the mount. I think it is pretty well integrated in that spot. It has good airflow, and the wiring passes through between the seat stays, so it will help prevent the wiring from being too eye catching.



Yes, I am missing fasteners. I didn't have enough M5 hardware, so I will have to order some. Once I am finished with all the prototyping, then I will order hardware.

Also, I learned a lesson about battery safety. I was mocking up the battery location in the triangle when the charge connector brushed against the sprocket. There was a tremendous flash, and the charge connector got burnt, and one of the sprocket teeth got ruined. I should be able to save the sprocket with some careful file work. Now the battery connectors are bagged, and I have to order new XT60 connectors.

Notice the tooth with the gold material from the connector welded to it. THe sprocket that doesn't have the chain on it...

I took the damaged sprocket off and cleaned it up. You can see the violence of the arc in the smoke pattern on the sprocket.




A little grinding, and the sprocket is salvaged.




A few more shots of the motor mount.








I ground a notch in the mount to provide clearance for the rear derailleur cable.

I got busy with the lathe to make a few spacers. All for the motor mount.




First I cut a spacer for the bottom bracket. I was having an issue where the bearings could move side to side inside the bottom bracket, so I cut a spacer to make the outside bearing stay in place. The axle for the pedals was loose and sloppy because that bearing was moving around, the spacer made it nice and tight.



Next I cut a couple of spacers so that I can replace the weird 4 bolt setup on the motor mount with two long and strong through bolts. Here's all the spacers.



The long spacers will replace this threaded piece... See how I have set the spacer there.

..............................