E-Freeride project - Backfire LRS

So finally I'm building my first e"bike".

I've been reading a lot on es during the last year and was initially aiming for a 125 conversion but now I'm on the way with an e-freerider
and with the 125 project pushed to somewhen later I'm getting parts that I will probably be using in the bigger vehicle when it's due.

This build is most likely going to happen during the next 2-3 months.
Feel free to contribute or challenge my thoughts.

The parts I already aquired during the last 2 weeks:
The motor should end up in the frame triangle

some nice downhill rims with 203mm discs mounted (the first screws I put in - groundbreaking so to say)

Turningy Wattmeter

Good brakes

The GNG motor

A nice fork ... which will probably be switched out for a DC fork because I really don't want to go over the handlebar at high speed.

24x 38120SE Headways with 9ah



I will make 2x12S batteries as as soon as the smart bms from bmsbattery.com arrives. Also I'm waiting on some CCCV chargers
I ordered weeks ago through mistertao.com.

I will make first experiments with the GNG kit mounted (after I bend everything to the right angles) - but will later on machine
a motor mount for the frame triangle and switch to either bike or cart chain for the 1st stage reduction.

Opinions/suggestions welcome.
I will update the thread as I make progress with the build.

I'm curious where the battery gets carried. Rear rack is not so ideal for dirt. Or is this a freeride bike, to be used on street?

I hope to be able to fit those also in the frame triangle. That's why I got the 3-battery-mounts.
I haven't gotten around to playing with a carton mockup / cad design - but if I can't fit all inside the triangle
I think 1 pack could also go on the upper bar.

Yeah, that was my thought. If the motor is in the triangle, it eats up lots of your avaliable space. Then you have 24 headways, that tend to take up a bit more space. do get as many as possible into the triangle, or near the top bar or handlebars.

Time flies.
I'm still planning on having that bike done by the end of February.

So I put the bike together. Some minor inconveniences like finding the right adapters for the FSA bearings to the suspension,
getting a smaller back breaking disk because the frame only takes a 160mm disk and so on.

That's how it looks now (I now even have the back brake attached but no new pic)

That's one of the battery packs (took me like half a day to solder the silicone cables to the connector that was provided with the BMS).
But I guess it'll take another few weeks for the 13s connectors to arrive from somewhere in Asia

I got two of the Smart BMS

unfortunately the led's aren't placed anymore so I got started soldering some resistors - but am unfortunately still waiting for 0603leds
(for over a week now).

I've been busy doing quite some CAD stuff like this 2-chainwheel crank with freewheel
and a motor mount and reduction (that I will also post here as soon as it's complete enough).

The plan is to machine a whole triangle from aluminium to mount in the frame triangle to be able to omit the whole the front cover of the brushless motor I got.

That motor is rated at 67rpm/V and I got myself some nice cart chainwheels with 60 teeth and cogs with 9 teeth so that should give me
a cadence of about 2.5V*24*67rpm/V*0.9*9/60*0/60=81.4 to 3.65V *jada*=118.9
-> with 56/11 that should yield in 50kmh to 73kmh (< wow that would be nice).

I have no idea if anybody here uses 219 cart stuff - but those are really cheap and since they are specified to ~39hp I think they should
last a lot longer on my ebike.

Also by now the KBS72121,50A,24-72V with high speed motor option arrived - so I feel confident that the right things will be happening

So my freewheel-chainwheel is finally taking form.
After I did a first test run with chipboard a few weeks back - I finally managed to stay for another 7 solid hours until
the small CNC mill was done chewing away at the aluminum.

I will gladly put the files on github somewhen later - if anybody is interested.
The red chainwheel is a 219 go-cart one.



^^ those go back to back (freewheel on the right side, screwed on a trial crank, ball bearing on the left side.

With any luck I should be able to get some use out of this sucker as a regular bike the next days and can then work on the motor mount
(which will go in the frame-triangle - and will also be a milled aluminum piece.

Time flies.
I'm still planning on having that bike done by the end of February.

Click to expand...

I THINK YOU UNDERESTIMAtED WHAT IT TAKES TO BUILD ONE FROM SCRATCH.

Hope you get it running before it snows again. :lol:

dan

You could say that - you could also say I just overestimated the time I could claw away from other projects to do this build.




So now I have a "regular" bike with two freewheels. I can get rid of the one in the back wheel and even have recuperation (or at least save on brake pads). Next up motor mount.

So it looks like I stopped posting updates when I was done with the dual-chainwheel-freewheel.

I was busy working and investing a lot of time in rebuilding my local hackerspace. I had to take my remaining vacation for this year - and since I always have to work
on sth I find sensible - I went ahead completing the build.

I got my 0603 leds

back in January and soldered them to the smart bms from bmsbattery.com.
After completion I noticed that the frockers from bmsbattery programmed them for LiPo instead of LiFePo4. Since I didn't want to spend the 100$ on
the i2c programmer I got stuck and frustrated. I looked on the web for an alternative software - since the O2micro one wouldn't accept any
of the cheap USB-i2c adapters I had at hand.
I found a russion ubuntu distro - but then lost interest pursuing it any further. (I think it works if you have the right laptop - taking i2c from the external
VGA connector)

To get the sprocket on the motor shaft I had to disassemble it to machine the shaft. (few hours May 2013)
pictures of the "450W" gng motor



Lathing off the pulley

(yeah I know ...)


Ready for the sprocket



Shortening, drilling and taping the shaft with stator


I also lathed the front and back of the motor because I want to mount it directly in between two aluminium plates.
Alos you can see I started milling the axle for the 2nd reduction and the bearing mounts to also mount those directly into the aluminium plates.

The first motor test (one evening in May 2013 @shackspace

I would submit a video - but I have no idea how to get it from picasaweb albums to youtube without a hazzle.

First mockup of the motor in the frame (using acrylic because I can machine it way faster). (1 evening August 2013)


Starting working on making a square key realizing later it's just not worth putting more time in it and buying a woodruff key set on ebay.


Measuring the profile of the frame at certain positions with a Faro 3D arm (ah man ... why couldn't the frame just be made from a round tube).

Takes about a day ... + another:



So much for catching up... now to last week.

Going to town with a dremel on both axis:


Machining the first set of motor mounts (if somebody wants the set I give it away for free).
CAD will go on github sometime soon.

Motor wedged in between:

First test mounting it to the frame:

Bearings in holders mounted to the motor mount plates:


Back to making the axle:

Because I'm so lazy it pretty much all has to work on the first take. Not necessarily the milled parts - but the work you get your fingers dirty
I don't particularly like to do twice (but I cheat enough to make it work)

Lathed endcap.


Milled last missing chainwheel-holder (just slightly modified from the freewheel one):


Here you can see that I modified the motor mounts to be able to adjust the chain tension (motor-chainwheel) by rotating the axle bearings.

Also I milled circular slots to adjust the chain tension on the other side by rotating the whole motor mount.
These get secured with 6 M5x20 on both sides ... will see if that's enough (I haven't calculated it - same goes for the bearing mount rotation).

I reconfigured my battery pack because I now have more space in the frame than initially planned (see acrylic motor mount) -
also I had to connect them up in parallel for a day to even out ... frocking BMS setback.

I decided to throw money on it and ordered some more of the smart BMS (which will most likely end up in the e-kickboard I'm also working on at the moment).
and the programmer (mother of ... why didn't I just do that a lot sooner?!)
Also I found a quite nice 24S bms which I find quite nice - though not really a bargain in my opinion - but I don't want to build my own ... and I want to have a hazzle free charge-setup - so I just ordered one.

Now it's just a 24S pack

Balancing leads will be back once I have a working bms.
Also I will build an enclosure from 6mm neoprene that I just ordered.

Wiring up the throttle and kelly controller for a first ride ... I needed to just get that done.

Good old zip ties:

and 2.5m 6² leads from the battery (to put it in the backpack).


I still need to get a relais or emergency cutoff switch and will make a video tomorrow.
Don't know if I can beat the guy who claims 90kmh on a gng motor ... but I calculated the bike to 80kmh at some point.

Also I need to figure out what went wrong here:


Maybe I frocked up with the electrics ... but I only connected the thick wires (gnd, +24S) to the controller and the thin wires (gnd, +16S) as power
for the controller (so it wont get too high voltage when recuperating ... which I don't do at the moment (I still need to block the freewheel in the back wheel).
Or it happened charging the capacitors ?

I didn't notice the burnt wire till after the first ride - which was quite nice (a bit noisy because of the three chains) at around 40kmh.
I'll recheck everything tomorrow, programm the controller to 3kw, shorten the motor power wires and hopefully make some good videos and
my personal speed rekord.

Full album is here ... unfortunately I didn't capture more.

Wow, your build looks like it's coming along nicely. It must be nice having such tools at your disposal.

skyungjae said:

Wow, your build looks like it's coming along nicely. It must be nice having such tools at your disposal.

Click to expand...

"You do what you must with the tools that you have at the time"


But yes, I feel lucky. I really admire what other people get done with a lot less resources - e.g. Building a triple stator axial flux motor <- that guy is awesome.

At the moment I make use of a small non-CNC lathe and think the parts didn't come out too shaby.
What I use most is a 1.4m x 1.4m table CNC mill that's built mostly from parts from the scrapyard.

The thing is - getting access to those machines gets easier through community-run workshops/fablabs/makerspaces - you should definitely check out if there is one in your neighbourhood if
you want to have access to those kinds of machines - or they can also be built relatively cheap nowadays ... check out linuxcnc.org if that is of interest.

The 3D arm is luxury - though I would have probably been faster with drawing on paper, scanning or photographing and importing that to the 3D software.

Now imagine what you could do with a big lasercutter / laser sintering machine

Nice looking build. I really like the way that your mounts use two frame tubes for rigidity. Twisting is a problem with the stock GNG design.

Whered u pick up the headway 24s battery. Is that 72v?

danjpendleton said:

Whered u pick up the headway 24s battery. Is that 72v?

Click to expand...

I bought the cells and cellholders from lipopower.de and assembled them myself - which is really easy.
Attaching the bms is a bit more complicated - but you should definitely have one - and I'm just waiting for a new one.

very nice....so what happened. you spent alot of time to detail and machining...i like your project.

I have the same model. check out the welding near the rear drop out. it comes out sheer as a single tube weld to the alu dropout. it is weak. it cracked after 4000k when i jumped off a curb. reinforce it with 1cm of carbon fiber epoxy. Other than that i have the same bike.