OpenEMoto

trazor said:
minde28383 said:
would you write your front and rear sprocket tooth number and speed you reach with your ebike. Also controller settings, batt and phase amps.
Did you ride hub before?

With the "big block" motor at 72v, with 12t sprocket and 92t drive, I get 55Km/h. The torque is "a lot".
I use a Kelly KBS 80AMP with all settings at "maximum" :)

Altough not the same frame, the transmission is the same and sounds like this https://www.youtube.com/watch?v=7YO6QAL7AyU&t=112s

I ride a MXU3k hubbie too. If a hub sounds 1 and an MX dirtbike sounds 100, I would say that my bike sounds 10. My chain bike does not bother anybody, even if I pass at 1 meter.

It's so hard to tell from video sound what it actually feels after an hour ride. I'm little bit custom to hub silence with sine controller. It must be I'm spoiled, therefore, envy to those who have mid drive with a belt.
 
I'm researching mid drives recently...
If you will ever feel like more power and ready to destroy your bicycle rear hub get Denzel (Cyclone) 7.5kw motor (7.2kg 4500RPM 72v 50Nm on motor axle, 120A batt short peaks).
 
Nice build!

A Fox40 fork is pretty tough in my experience. The pitbike forks are super cheap and heavy and have a really poor suspension feel IMHO.

If you're going to be jumping it huge, rather than a pitbike fork, a real motocross fork is the ultimate in winning strength and performance.

KYB SSS forks are as good as it gets for dirt suspension, and due to being used on a bunch of Yamaha and Kawi 250cc-450cc motocross bikes they are cheap and abundant on ebay.
 
minde28383 said:
I'm researching mid drives recently...
If you will ever feel like more power and ready to destroy your bicycle rear hub get Denzel (Cyclone) 7.5kw motor (7.2kg 4500RPM 72v 50Nm on motor axle, 120A batt short peaks).

Yeah, I would like to get a Denzel motor to try. Will require to to design the two plates that fix the motor to swingarm. And that will be the ultimate test for the 'poors man' rear hub that i've crafted. I will need to call my machinist to make it fit the 219 sprocket. I don't remember where, but I heard that the 219 transmission can keep up with 20HP maximum, so we are safe.

As a side note, I'm starting to build another frame, but in this case the swingarm will be for mi MXUS3K, so it will have structural differences and 12mm wide dropouts. Hope to make OpenEmoto compatible with different motors. BigBlock, Denzel, Hubbie and maybe the golden motor that cames with the Sur-Ron.
 
liveforphysics said:
Nice build!

A Fox40 fork is pretty tough in my experience. The pitbike forks are super cheap and heavy and have a really poor suspension feel IMHO.

If you're going to be jumping it huge, rather than a pitbike fork, a real motocross fork is the ultimate in winning strength and performance.

KYB SSS forks are as good as it gets for dirt suspension, and due to being used on a bunch of Yamaha and Kawi 250cc-450cc motocross bikes they are cheap and abundant on ebay.

A FOX40 is over my budget, and I don't really think that it is much more strong as my current Marzocchi (but of course is way better in suspension characteristics)

I would be interested in trying MX forks. What are the sizing standards? I don't think those can fit 1 1/8 headsets. For what I searched, those forks use some kind of roller bearings. Are the mating cups standard? are they press fitted on the headtube? What is the headtube diameter? Sorry, I'm a complete noob on "real" dirtbikes. I will need to buy a second hand MX and study it.
 
You can easily lathe up whatever head tube you need.
 
pit bike and bicycle head tubes are a different diameter. Maybe it's possible to lathe apaters / cups which fits bicycle headtube and fits roller bearings of the pit bike fork, not sure though.

I too tend too to pit bike forks but I don't see good bicycle forks to brake, even cheap knockoff double crown Zoom for 120usd 3,5kg is holding up for fast and heavy ebikes. Therefore I can't justify few additional kg for my calm riding style, yet.

added some pics comments.
 

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very nice project!

your BOM links to a DNM shock w/ 550 pound spring. is it too soft for your build? i'm curious because i'll be using a 550 pound also, but 220mm

check out the Rockshox Domain dual-crown. these have steel stanchions. should be quite tough

dla3ph2.jpg
 
Overclocker said:
very nice project!

your BOM links to a DNM shock w/ 550 pound spring. is it too soft for your build? i'm curious because i'll be using a 550 pound also, but 220mm

check out the Rockshox Domain dual-crown. these have steel stanchions. should be quite tough

dla3ph2.jpg

Thanks!

About the shock... It isn't as easy as droping a a shock on the bike and expect to be soft or hard. On my previous bike I've done that mistake and ended with a super short rear wheel travel, impossible to compress after first inch. With OpenEmoto i've taken a more scientific approach.

I warn you that I'm not an expert on the subject, and maybe I'm about to say nonsense based on reading blogs.
The suspension characteristics will depend on your shock compression/rebound system, shock spring, shock travel, linkage system, intended wheel travel, intended force curve.

For OpenEMoto I aimed to:

- 210mm rear wheel travel
- about 2400N force in maximum compression
- enough space to fix the swingarm mounted motor
- monopivot lynkage system (simplicity)
- 18 inch wheel swingarm lenght
- 550 pound spring / 240mm shock lenght / 76mm shock travel (default DNM shock characteristics)

And the result was this shock eye positioning and force curve:

2018-05-04 01_08_04-Linkage X3 (Eduardo Roldan).png

The screenshot is taken from Linkage software (http://www.bikechecker.com/news.php) I've brought the 25usd version and it is awesome. This sofware can design sophisticated bicycle suspension systems, much more difficult than our monopivot setups, so there is a lot of stuff to just ignore. Check this video https://www.youtube.com/watch?v=Ozlu1I_BHLo

At the end after all this research, i've a bike that has a plush rear suspension that everybody likes. I would liked to have more "progressivenes" (instead of the very linear curve) , but looks impossible with a standard shock and monopivot linkage.

I hope this helps in your build. If it is too late to think about this stuff you can source a local spring maker and probably have a good enough suspension if you are out of luck with the standard spring.
 
haha yeah it's too late for me to change my leverage ratio :lol: my swingarm has more leverage on the shock than yours so i might need a harder spring:

https://em3ev.com/shop/dnm-burner-rcp3-spring/?currency=USD

BTW when you sit on your bike what % of sag do you get at the rear shock? i'm actually aiming for something like 30 to 35%. i want something soft-sprung. the fork i'll be using has rockshox SOFT spring in it. i won't be doing any big jumps anyway...
 
You're a great rider, nice video and nice build.
 
Somebody asked in private about what happened to the Marzocchi fork after the nasty crash (https://endless-sphere.com/forums/viewtopic.php?f=2&t=92618&hilit=nasty+crash) and I think it is worth sharing:

The Marzocchi is still running fairly well. Since one leg was slightly bent, the stanchion was stuck. I had to take it out, and remove one of the bushings of that leg. One similar to this http://marzocchimoto.blogspot.com/p/buy-bushings.html
Now the fork is running with 3 bushings instead of 4, and it is pretty solid anyway. Probably did 50 hours with it and no signal of malfunction.

BTW, my second OpenEmoto build is finished (as always, bare metal, no paint yet), posting photos soon.
 
I got bored of riding alone and built a second OpenEmoto, with improvements:

  • Higher seat
  • EVA Rubber fenders
  • Modular battery
  • Improved dashboard
  • Alternative hub motor swingarm (I had a mxus3000 clone lying around)
  • Machined headtube, for semi integrated headsets
  • JBD Smart BMS

Here are some photos:

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As always, source files on github https://github.com/eroldan/OpenEMoto/tree/1.1
 
After who knows how many hours of joyful riding the drive sprocket gave up:

IMG_20181111_033618.jpg

This process was slow, and the last time I checked the tooths were a hair of steel.
Luckily, I've purchased couple 12 tooth when ordered the motor from lightningrod's store, so no downtime :)

I've found that https://azusaparts.com/product-category/sprockets/b-type/for-219-chain/ carries these sprockets at better price. I think they are the same but not received them yet so maybe I purchased paperwheights :lol:
 
Great.
That of having 2 electric bikes in which only varies the motor gives to make a good comparative.
Then share the differences between the two at the level of driving, that should be interesting :)
 
Antenor said:
Great.
That of having 2 electric bikes in which only varies the motor gives to make a good comparative.
Then share the differences between the two at the level of driving, that should be interesting :)

The differences between mid drives and hubs is well understood. Basically:

Hubs are an anchor in your rear weel. That is ok for street driving but not good for offroad.

Hubs pros:
- Almost zero maintenance
- Quiet
Hubs cons:
- Easy overheating since stator is gapped in air
- Less efficient than higer rpm motors
- So heavy that deform your rim in a crash, pothole, etc.
- Impossible to achieve a good suspension system
- Power/weight ratio is lower than inrunners
- Mechanical advantage is fixed: no trade torque for speed

Mid pros:
- Don't have all the Hubs cons
Mid cons:
- Transmission requires maintenance (previous post)
- Noisy

My friends really enjoy the hub bike since they don't have high "driving standards" and can follow me in the trails without doing jumps or stepping over logs.
 
Pls also add "noise"
This is a huge issue when comparing hub vs mid drive
 
Nice vid! Thats about all ive done on my kuberg so far also. It climbs hills like a champ but im no trials rider...only in my dreams
 
trazor said:
About the shock... It isn't as easy as droping a a shock on the bike and expect to be soft or hard. On my previous bike I've done that mistake and ended with a super short rear wheel travel, impossible to compress after first inch. With OpenEmoto i've taken a more scientific approach.

I warn you that I'm not an expert on the subject, and maybe I'm about to say nonsense based on reading blogs.
The suspension characteristics will depend on your shock compression/rebound system, shock spring, shock travel, linkage system, intended wheel travel, intended force curve.

For OpenEMoto I aimed to:

- 210mm rear wheel travel
- about 2400N force in maximum compression
- enough space to fix the swingarm mounted motor
- monopivot lynkage system (simplicity)
- 18 inch wheel swingarm lenght
- 550 pound spring / 240mm shock lenght / 76mm shock travel (default DNM shock characteristics)

And the result was this shock eye positioning and force curve:

2018-05-04 01_08_04-Linkage X3 (Eduardo Roldan).png

The screenshot is taken from Linkage software (http://www.bikechecker.com/news.php) I've brought the 25usd version and it is awesome. This sofware can design sophisticated bicycle suspension systems, much more difficult than our monopivot setups, so there is a lot of stuff to just ignore. Check this video https://www.youtube.com/watch?v=Ozlu1I_BHLo

At the end after all this research, i've a bike that has a plush rear suspension that everybody likes. I would liked to have more "progressivenes" (instead of the very linear curve) , but looks impossible with a standard shock and monopivot linkage.

Very cool project! Nice work.

The easiest way to get more progression on your bike would be with an air shock.

That's great you are using Linkage for your build! I've used it a bunch over the years. What's the leverage ratio look like?

On single pivot (no linkage) bikes I found that using a longer 267mm long 89mm stroke shock was easier to get the feel I was after. This was due to lower leverage ratios allowing the use softer spring rates 350 or 400 which gave a better rebound range too. Even then I never had enough progression to get the ideal balance of supple for traction and then firm for big hit support.

You could make your bike more progressive feeling with an air shock. Air shocks are more progressive than coil shocks anyway and modifying an air shock to be even more progressive is very easy. The theory is that if you reduce the size of the positive air chamber with spacers or rubber bands then you increase the compression ratio of the airspring meaning that it will be softer at beginning stroke and harder at end stroke when compared to a coil shock. An additional benefit is the nearly infinite spring rate adjustments.

Your frame design looks like there would be room for a scissor link or moto pro link style something to get more mechanical progression if you didn't want to spend money on a high end DH air shock. If you did go that direction then I think a good starting point would be a around 3:1 starting leverage ratio down to 2.1:1.
 
Buckow said:
trazor said:
About the shock... It isn't as easy as droping a a shock on the bike and expect to be soft or hard. On my previous bike I've done that mistake and ended with a super short rear wheel travel, impossible to compress after first inch. With OpenEmoto i've taken a more scientific approach.

I warn you that I'm not an expert on the subject, and maybe I'm about to say nonsense based on reading blogs.
The suspension characteristics will depend on your shock compression/rebound system, shock spring, shock travel, linkage system, intended wheel travel, intended force curve.

For OpenEMoto I aimed to:

- 210mm rear wheel travel
- about 2400N force in maximum compression
- enough space to fix the swingarm mounted motor
- monopivot lynkage system (simplicity)
- 18 inch wheel swingarm lenght
- 550 pound spring / 240mm shock lenght / 76mm shock travel (default DNM shock characteristics)

And the result was this shock eye positioning and force curve:

2018-05-04 01_08_04-Linkage X3 (Eduardo Roldan).png

The screenshot is taken from Linkage software (http://www.bikechecker.com/news.php) I've brought the 25usd version and it is awesome. This sofware can design sophisticated bicycle suspension systems, much more difficult than our monopivot setups, so there is a lot of stuff to just ignore. Check this video https://www.youtube.com/watch?v=Ozlu1I_BHLo

At the end after all this research, i've a bike that has a plush rear suspension that everybody likes. I would liked to have more "progressivenes" (instead of the very linear curve) , but looks impossible with a standard shock and monopivot linkage.

Very cool project! Nice work.

The easiest way to get more progression on your bike would be with an air shock.

That's great you are using Linkage for your build! I've used it a bunch over the years. What's the leverage ratio look like?

On single pivot (no linkage) bikes I found that using a longer 267mm long 89mm stroke shock was easier to get the feel I was after. This was due to lower leverage ratios allowing the use softer spring rates 350 or 400 which gave a better rebound range too. Even then I never had enough progression to get the ideal balance of supple for traction and then firm for big hit support.

You could make your bike more progressive feeling with an air shock. Air shocks are more progressive than coil shocks anyway and modifying an air shock to be even more progressive is very easy. The theory is that if you reduce the size of the positive air chamber with spacers or rubber bands then you increase the compression ratio of the airspring meaning that it will be softer at beginning stroke and harder at end stroke when compared to a coil shock. An additional benefit is the nearly infinite spring rate adjustments.

Your frame design looks like there would be room for a scissor link or moto pro link style something to get more mechanical progression if you didn't want to spend money on a high end DH air shock. If you did go that direction then I think a good starting point would be a around 3:1 starting leverage ratio down to 2.1:1.

Thanks for your support! :)

You are right. The best way to bring some progression will be to use a shock with progressivity, and usually that means air shocks, right. There is a nice article that talks about the "linkage vs PDS" on the dirtbike industry. Basically, is what we are talking about: https://dirtbikemagazine.com/ktm-suspension-shootout-pds-vs-linkage/

About shock sizes, I'm using the DNM 240mm with 76mm travel, 550 lb/inch spring, similar to what you suggest. I would love to play with alternatives but it is the only good enough low budget shock (around 130 dollars). This project is about DIY and keeping costs low, but please if you have brands and models that you think can fit on this build post them since I would love to try new things (at least when I get the budget to spend in high priced shocks).

About adding a pro-link style to the frame... I don't think it is an option. Too difficult to manufacture and it adds weight. Weight reduction is my first objective since start. I've spent long nights thinking on how to make things simple to build and keep material usage (weight) to minimum.

If you have your linkage software installed you can check by yourself my design, all sources are open. Linkage file is here: https://github.com/eroldan/OpenEMoto/blob/master/Linkage/OpenEmoto%20v1.1.ltx

Currently the leverage ratio goes from 2.6 to 3.0 in a 209mm travel.

Seems that you have experience building bikes. Contributors are welcome, like any other open source or open hardware project.

BTW, welcome to Endless Sphere! Don't forget to subscribe to topics that you are interested (like this) using the wrench icon at the top of the page, so you get a mail when the topic is updated. Don't be shy and post your bike build photos ;) Byebye
 
usertogo said:
trazor said:
I've a new video but isn't something cool. I had a crash and broke my Marzocchi 380.

Check this topic https://endless-sphere.com/forums/viewtopic.php?f=2&t=92618

The crash was big, but only impacts with the floor. Still my fork left bottle is bent in some way, and the stanchion can't slide. I feel that DH stuff is very expensive and not so strong. Should I go to pit bike forks? They are 1 1/8 compatible? recommended brands? Other ideas are welcome.
I looked at the design and thought it is ideal for that type of front suspension where no tubes have to slide like a double A arm front suspension for example with a mono shock like in the back... I remember there was a discussion on the endless sphere facebook page with lots of videos about alternative front suspensions (Those long tube suspensions appear simple but they are expensive and very vulnerable) Needless to say there is no way finding a direct link to those facebook posts, what I found is a free scientific papwer about alternative front suspensions: https://www.researchgate.net/public...tive_front_suspension_systems_for_motorcycles

I also thought that battery space could become a bit more linear to fill that belly with batteries more evenly...

Thanks for your ideas. For now, designing my own front fork is out of my reach. Do you want to do it? I gladly build your cad files if you provide them :)

The battery compartment is not something I'm proud about. The last moto have a modular (4 screws) battery so in theory is possible to put more batteries in a cage below the belly. I think I will do it at some point. Maybe at the next hobbyking lipo sale :lol:
 
Update on new battery design. I wanted to make it splash proof and probably able to clean it with a hose. Set on a thick rubbery paint designed to paint the floor facing side of cars.

IMG_20181219_190128.jpg
IMG_20181225_170642.jpg
IMG-20181219-WA0012.jpg

I'm happy with the outcome:
- Probably not worsened thermal transfer capacity (no air gap added)
- Almost no weight penalty.
- Splash proof
- Smart BMS bluetooth still works (left the bluetooth module inside, of course)


More updtes soon: My kelly controller melted after phase wires shortened (it signaled the fault about 10 times and I ignored it). Got a Denzel 4500 motor kit. The price is awesome including motor, controller, shipping. MXUS300 go out, Denzel goes in. Same swingarm size.
 
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