Sn0wchyld's 12kw custom frame mid drive

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Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Sun Jan 24, 2016 8:20 am

Thought I'd start a new topic to document a project I've been working on quietly on and off for a few years now... a custom frame for a mid-drive ebike. Its been through many iterations while i've tought myself how to use CAD software, some basics on bike geometry and what hardware I wanted to utilize in the build.

Heres some of the early designs, which are almost embarrassing to show now :P. These are before i got my hands on a CNC router...

2012
Image
Image


2013 - 2015
Bought a cnc router, so the design changed as a result - this is the latest version form mid last year
Image

2016
new frame 2016 (Custom).JPG
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Larger pic
new frame 2016.JPG
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I actually prefer the look of the 2015 version, it looks cleaner and leaner, but I built it with little thought to the actual practicality of building it, and how it would perform, hence the redesign. the 2016 has far more thought given to making sure everything fits with ample room, and that its all 90% buildable with tools and skills i have right now. Most of the designs were built with John's mini monster in mind, though the Revolt RV120pro and 160s have been considered too, as well as a few others.

the current version has been made with a few criteria in mind:
Predominantly, or entirely weld-less frame
This is mainly to facilitate changes i'll probably want to make after riding it, as many parts will be transferable to a new frame, and making small tweaks to geometry wont require construction of an entirely new frame. I'll probably make a welded frame once I have some welding skills and have buit a frame or two to come to a design im happy with.

2 speed drive for both pedals and motor
I like 2 styles of riding - slow, technical trials like riding and also flying down trails. a 2 speed means I can crawl up steep terain with silly ammounts of torque, without ever stressing the controller or motor, while still enabling a good top speed.
I'll be building a 2 speed single engagement dog box for this:
dogbox.JPG
dogbox.JPG (51.07 KiB) Viewed 5694 times
From left to right is 1st speed (with freewheel), 2nd speed (both going to the rear wheel), the dog drive, the freewheel sprocket from the pedals, and the motors 1st stage sprocket.
The pedals and the motor come to a single drive shaft, that also serves as the axle for the swingarm. This will hopefully eliminate much of the pedal jack and chain growth that a high pivot swingarm would normally suffer from. 1st should get me to about 30km'h, with 2nd giving somewhere round 70.

high pivot swingarm
I've never actually ridden one, but a rearward traveling suspension ark really appeals, compared to the relative 'bang' you get with traditional geometries on square bumps. It also makes chain routing relatively easy vs a pivot point centered near the BB.

Capacity for 20s 15ah or more - based on the 4s hardcases I have plenty of right now. I'm simultaneously making sure it'll fit about 20s20ah worth of 18650's too.

Capacity for controller inside the frame, heat-bridged to the side covers.
I'll be using a MAXe (gen1) so it's ideally suited to this with its flat body.

Capacity for johns mini monster motor.
I've had it for about 4 years now! time it got used, and it looks to have the power density im after. I'll probably end up modifying it pretty extensively with an aim of getting a solid heat path to the frame of the bike to aid cooling.

'stealthy'
One thing i dont like about the stealth's, the vectors etc is the blob of triangle that (to me atleast) stands out as a ebike frame. I want to keep this thing as slim as realistically possible in profile, with as little hardware as possible visible. So everything (motor, controller, batteries, HUD etc) will be inside the frame. Also makes the bike a bit safer too as a bonus.

Not too heavy
The goal is a total weight under 45kg. Probably a bit ambitious without a welded frame or huge time spent with optimization software/simulations (which i cant afford atm). Frame thus far is shaping up to be in the 7-8kg range, which im pretty happy with given my old norko is around 5kg Should result in a empty rolling frame of about 25kg (norko was about 19kg before electrifying). With a 10kg motor, 7.5kg battery and a 1.5kg controller 1.5kg 2 speed, 45kg doesn't seem impossible, and sub 50kg should be pretty easy.

Capacity for 21" moto wheels.
This would likely take it beyond the 45-50kg mark but I'd like it as an option, since moto wheels provide so much more durability and grip. I've got some rather nice 21'' rims and tyres waiting, but i might save it for use with a lighter motor to help even things out (possibly a revolt 160s)

Bombproof
My biggest beef with all my builds to date is their lack of durability. I've been breaking spokes, overheating, or having some other issue that's meant ive never really been able to rely on my bikes, as such i've always babied them to some extent. Hence why im over building many aspects of this frame (its mostly cnc'd ally, ranging between 6 and 15mm thick). Its also why I plan to have the motor and controller 'heat sinked' to the frame - with the idea that overheating will be all but impossible even when crawling up steep hills all day.

The frame geometry is loosely based on my norko, which i quite like the feel of. The main changes (other than the swingarm) are a extended wheel base (1.3m, up from 1.2ish) and a slightly lower BB (about 25mm). Shock compression ratio remains approximately the same, with a slight rise through the range of travel, that should be around 8.5'' in total.

if this one works out ok I'll probably build a 2nd bike to be much lighter as a little tear around, but this current one is one that I'd like to both commute on and tear around on.


TLDR:
its a custom, heavily built frame with a goal of having a dual purpose (thrash and commute) ebike that'll never quit and (hopefully) rarely break down. 2 speeds, 10-12kw, 20s15ah 40-50kg.
Love to hear any feedback or ideas. Cheers all.
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Re: Sn0wchyld's 12kw custom frame mid drive

Post by magna_503 » Sun Jan 24, 2016 10:07 am

Nice

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by oatnet » Sun Jan 24, 2016 1:33 pm

Hi Sn0w!

Looks like the start of another fine build, subscribed! :D

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by macribs » Sun Jan 24, 2016 2:29 pm

*Subscribed*

That is some nice work, glad you came out of the closet snow and shared this with us (frame design that is)
Man a purpose built frame for John monsters or Revolt's. I tip my hat off to you sir.
If you can make the revolt 160 fit I sill start nagging you already to make up frames for sale :)

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Mon Jan 25, 2016 1:37 am

macribs wrote:*Subscribed*

That is some nice work, glad you came out of the closet snow and shared this with us (frame design that is)
Man a purpose built frame for John monsters or Revolt's. I tip my hat off to you sir.
If you can make the revolt 160 fit I sill start nagging you already to make up frames for sale :)
haha nah i've had these designs up on my other build threads but now seems worth while putting it in its own thread.

The current design will fit any motor up to about 175mm dia and 125mm wide, so not those massive motors john has but his smaller one that had a series parallel switch inside. I'll be locking that in high given there's no point in the series parallel with the 2 speed dogbox. I'm also considering re-terminating it in delta given this motor really needs 150v+ in its current config to make the most of its power potential. delta should make 100+ amps continuous a real possibility, and make it better suited to the 80 odd volt limit of the max-e.

Designs nearing completion - some more pics:
new bike (Custom).JPG
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new bike 2 (Custom).JPG
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new bike inside (Custom).JPG
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new bike inside2 (Custom).JPG
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shows how things fit - blue box is a maxe, black boxes are 4s hardcase batteries (the fit 3 abreast, so there's 15 there in total) Johns motor in red, and the sprockets in green.

Closing in on about 7-8kg (currently 6.5kg, but there's a few bolts to go in this one :P. Most however are the rather lightweight 10mm SS bolts often used to hold sprockets on to crank arms, and the dropouts on to my norko. Most others are m8 and m6.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by DanGT86 » Mon Jan 25, 2016 1:32 pm

Looks really great so far. I really like the shape of the frame for trials style riding. You could easily make the seat hinge at the front so it folds down and becomes a glorified shock cover like a seatless trials bike. When locked in the upright position it would be like a standard motocross bike.

I'm also a huge fan of the 2 speed gearbox for the same reasons. I am really into trials and have been trying to learn but also love high speed runs on gravel and dirt roads. Its hard to choose between the two when picking drive train components and expensive to have enough power to do it all well with the same bike. It does seem counter intuitive to remove the kv switching feature of the motor then have to build a gearbox to get similar functionality back. But you are far from a noob and I'm sure you have made the decision based on good info.

Out of curiosity, how do you and others decide the shock angle when designing a frame? Seems like the angle of the shock from tangential to the swing arm arc would give it a progressive nature. Is this factored into the design or just not significant enough factor to affect it?

Good luck with the build! Amazing cad work and design so far! I'm looking forward to watching this since I have also been dreaming for years about a mid-drive hubmonster or mid-monster build. The obstacle in my opinion has always been its just a little under powered for a full size motocross frame and to powerful for a mountain bike. A custom frame is the perfect solution for this.

oh, yeah, one more thing. This concept deserves way better than hardcase packs. I know they get the job done but after all that work on the frame it would be heartbreaking to fill it with low quality controlled batteries.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by SlowCo » Mon Jan 25, 2016 1:51 pm

Wow, very nice design!

As for cooling your motor have you seen the "Statorade" results? Might be a good idea to try:

http://www.ebikes.ca/shop/experimental/statorade.html Also read the linked posts in the product description.

I have no experience off road riding a mountain bike but I wonder if the seemingly high center of gravity isn't a problem. Or is a high CoG a benefit?

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by macribs » Mon Jan 25, 2016 2:07 pm

@Dan have you seen those Joby motors? Worth looking into if you are keen for a mid drive. Look at the video below.
First one that Joby e-bike is hammering 450 cc motorbikes at the track. Last one you get a better feel for how nimble it is. And there was also a brand new video I havn't seen before, so if you don't have either, enjoy.

Maybe you seen it and know about the motor, but if you don't take a look. They can wind the motor any way you please. Even 6 phase.
[+] Click for vids I did not wanna litter the thread
Last edited by macribs on Mon Jan 25, 2016 3:45 pm, edited 3 times in total.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by TorEddy » Mon Jan 25, 2016 3:03 pm

I love the solidwork of the 2016 frame!!

Just want to say that I prefer the 2015 frame, mainly because the chain on the 2016 frame, will lock up the rear suspension under power.
It also seems to have a higher center of gravity.

Just my two cents!

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by jansevr » Mon Jan 25, 2016 3:21 pm

Cool frame and nice CAD work. I would recommend a larger battery bay however especially considering 12kw power. At the very least mounting the conroller externally would not only provide much better cooling but also more room for batteries.

Looking forward to seeing the end result...there's very few people using johns motors which in my opinion are some of the best (in terms of quality and performance)

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Mon Jan 25, 2016 4:58 pm

sorry long post, trying to reply to everyone :P....
TorEddy wrote:I love the solidwork of the 2016 frame!!

Just want to say that I prefer the 2015 frame, mainly because the chain on the 2016 frame, will lock up the rear suspension under power.
It also seems to have a higher center of gravity.

Just my two cents!
given they both use the swingarm axle as a stage in the drive system, they'll both have the same effect on the suspension. I suspect that it will cause a small amount of squat under power, but can you explain how it would be any worse (or significantly worse) than a normal motorbike design, with the drive sprocket situated just in front of the swingarm pivot? im no expert on suspention performance particularly under load so it'd be good to know. cheers...

I had also given some thought to transfering the counter torque from the motor such that it is key'ed to the swingarm (like the reverse of a floating rear brake) that way it''d be as if the motor is mounted on the swingarm, eliminating any effects on the suspension entirely. That proved a royal pita to build though so i did away with that idea... for now :twisted:

COG is about the same between the 2015/2016 frames, this one's just got more junk in the trunk...

ps
to those interested im using fusion 360. free with built in CAM is a big selling point (its also really good software - not quite up to solid works yet, but they're constantly improving it so its geting damn close)
DanGT86 wrote:Looks really great so far. I really like the shape of the frame for trials style riding. You could easily make the seat hinge at the front so it folds down and becomes a glorified shock cover like a seatless trials bike. When locked in the upright position it would be like a standard motocross bike.
....... .It does seem counter intuitive to remove the kv switching feature of the motor then have to build a gearbox to get similar functionality back. But you are far from a noob and I'm sure you have made the decision based on good info.
......Out of curiosity, how do you and others decide the shock angle when designing a frame? Seems like the angle of the shock from tangential to the swing arm arc would give it a progressive nature. Is this factored into the design or just not significant enough factor to affect it?
........oh, yeah, one more thing. This concept deserves way better than hardcase packs....
Yea the battery choice is mainly due to thats what I have (bought quite a few when they were on sale + what i have on existing bikes) which saves me money untill i can afford (most likely) some 18650's.

re the shock angle, it depends what you want out of it. for me, i wanted it to steadily decrease the ratio (make the suspension 'harder' to compress) as it traveled through its arc. so it has a compression ratio of about 3.6:1 , but this drops a bit from about 4:1 to 3:1 as the path of the swingarm's shock axle goes from about 45 deg to the shocks compression path to more like 0 deg. I'll try to post a pic later on of what i mean, its hard to explain with words.


re the 2 speed/getting rid of the '2 speed' inside the motor, the internal 2 speed doesn't actually change anything about the motors output - it will still heat up just as much (for a given torque output) in 1st or 2nd. it only makes the motor easier for the controller to run. however, a 2 speed gearbox achieves almost as much for the controller, while generating less heat per unit torque output (vs 1st in the internal motor switching). There's a good thread on this that ill post if i can find it. basically, the kv of the motor has 0 effect on its max / cont power and torque. all the stuff about 'high torque' and 'high speed' motors is largely bunk, as each motor is capable of the exact same speed and torque, you simply need to change the ratio of volts and amps that you feed it to get the desired result.
A 2 speed gearbox however has the direct result that the motor puts more torque to the road for a given amount of heat (in 1st) while not needing to use any field weakening (an inherently inefficient process) to achieve a higher top speed. Field weakening is great, but you dont want to rely on it for any more than bursts of high speed unless your ok with wasting power.

SlowCo wrote:......

http://www.ebikes.ca/shop/experimental/statorade.html Also read the linked posts in the product description.

I have no experience off road riding a mountain bike but I wonder if the seemingly high center of gravity isn't a problem. Or is a high CoG a benefit?
yea im still tossing up between new side covers for the motor and the statoraid. I do kind of want to have the frame sealed, so the statorade wouldn't help much.

and yea the cog is a bit higher than what i'd call ideal (though its still on the line from the steer tube to the rear axle, so it wont feel top heavy) but its also a limitation of other factors (such as the high rear swingarm pivot) and wanting the bike to 'look' as much like a normal bike in profile as possible, while still leaving enough room for ample batteries etc. Enough people are pointing this out that i might look at a lower cog deign to see if its possible...


jansevr wrote:Cool frame and nice CAD work. I would recommend a larger battery bay however especially considering 12kw power. At the very least mounting the conroller externally would not only provide much better cooling but also more room for batteries.

Looking forward to seeing the end result...there's very few people using johns motors which in my opinion are some of the best (in terms of quality and performance)
yea the battery bay has a fair bit of extra room, it'd fit 20ah at a squeeze, or closer to 25-30ah with 18650's (thats with the controller inside). Moving it would free up some space, but it would probably get worse cooling given im attaching it directly to the aluminium frame (basically a giant heatsink) and i dont want to add that much weight in batteries anyway.
and yea, despite how difficult it is to use the motor (a 160s / 120pro would make the build WAY easier) i think it'll be worth it, this motor looks like a absolute beast, and quite small for its power potential.

cheers all.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by macribs » Mon Jan 25, 2016 5:16 pm

and yea the cog is a bit higher than what i'd call ideal (though its still on the line from the steer tube to the rear axle, so it wont feel top heavy) but its also a limitation of other factors (such as the high rear swingarm pivot) and wanting the bike to 'look' as much like a normal bike in profile as possible, while still leaving enough room for ample batteries etc. Enough people are pointing this out that i might look at a lower cog deign to see if its possible...


I remember a few years back (10-15 already?) some milestone R&D was done in the world of snowmobiles. For several decades the design of the frame and engine placement was a given - it was well proven and it worked. No one questioned it a bit. Then some skid doo engineer who also was a weekend dirt biker sat down at the drawing board. Changing everything. Seating position was raised several inches, and moved forward, same with gas tank, engine was moved backward. Heck even the running boards was redesigned to allow for moving more forward. It worked like a charm. Raised COG a little but also kept the weight centralized, dirt bike style. Since then it is the de facto design of all major brands.

I don't know if you can draw parallels between that design change and what we see here, but I would not be surprised if your design will work wonders.
I think SamD has been down that road with a few custom builds. Make he got something to say? Or maybe some skilled people could comment on this if that might work for e-bike frames as well.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by drewjet » Tue Jan 26, 2016 5:49 am

Very nice. I like the idea of the stealths, and others, but hate the heavy hub motor. Looks like you have nailed it.

Are you running 2 chainlines? One for the motor and one for the pedals?

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by John in CR » Tue Jan 26, 2016 8:28 am

Finally! I can't wait to see the finished rig and results, especially the high pivot that keeps the width out of the way of the cranks. You're such a mountain biking guy, why not go for the anti-squat and anti brake dive with regen by locking the motor axle to the swingarm? You'd have to put the dog shifter on the swingarm, but close to the motor that's in or near the pivot would have negligible effect on unsprung weight...virtually nothing compared to the 21's.

FWIW the Mini that I modded a bit for mid-drive is only 9.2kg and that's with sprocket and phase wires, and no changes inside, so below 9kg is a matter of simplicity. If you take one phase wire out through the hollow side where the shifter is, then you can go to really fat phase wires.

I didn't really follow the heat management plan, but I like simple, so I'd go with my already proven bladed ventilation and send the exhaust duct down and to the rear to bring a nice flow through the entire battery/controller/motor enclosure. You'd just need some kind of baffle and screen arrangement up front to make sure nothing unwanted gets sucked in.

Too bad while making arrangements to pull the money together a couple of years ago, the factory sold it's bulk stock of motor parts for the Mini's at various stages of assembly. They had about 100 complete motors worth of stuff. Half the stators were assembled and only half of those had the copper wound. We could have assembled exactly the motors we want. In high the Mini has an inductance of 300uH and a resistance of 54mOhm, so doubling the Kv would have made it a real 15kw motor at just 72V.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by Hillhater » Tue Jan 26, 2016 4:32 pm

Very nice bike,...but Is there really any point in keeping the pedals ?
No way will this ever pass as a "Bicycle" , and with 15kW or so, is the extra few watts of foot power worth the time or weight to build it in ?
For off road work , the extra ground clearance on reduced weight, it must be advantageous to just fit some pegs.?
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Re: Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Tue Jan 26, 2016 8:15 pm

Hillhater wrote:Very nice bike,...but Is there really any point in keeping the pedals ?
No way will this ever pass as a "Bicycle" , and with 15kW or so, is the extra few watts of foot power worth the time or weight to build it in ?
For off road work , the extra ground clearance on reduced weight, it must be advantageous to just fit some pegs.?
Bike will still be used on road, with power limited appropriately, so yes. I also like the appeal of getting some more exercise, even if it makes jack difference to the power output offroad, and offers some level of redundancy. Just having pegs would make the build much easier, but i wouldn't have enough places to use it (and aus registration for custom stuff is a royal pita and wallet). Weight difference is marginal, only a couple of kg on a 40-50kg bike. Beauty of the bolt-together frame however is that such a change is pretty easy down the track :wink:




John in CR wrote:...why not go for the anti-squat and anti brake dive with regen by locking the motor axle to the swingarm? ....

..... You'd have to put the dog shifter on the swingarm, but close to the motor that's in or near the pivot would have negligible effect on unsprung weight...virtually nothing compared to the 21's......

....FWIW the Mini that I modded a bit for mid-drive is only 9.2kg and that's with sprocket and phase wires, and no changes inside, so below 9kg is a matter of simplicity. If you take one phase wire out through the hollow side where the shifter is, then you can go to really fat phase wires.....

...I didn't really follow the heat management plan, but I like simple, so I'd go with my already proven bladed ventilation and send the exhaust duct down and to the rear to bring a nice flow through the entire battery/controller/motor enclosure. You'd just need some kind of baffle and screen arrangement up front to make sure nothing unwanted gets sucked in....

Too bad while making arrangements to pull the money together a couple of years ago, the factory sold it's bulk stock of motor parts for the Mini's at various stages of assembly. They had about 100 complete motors worth of stuff. Half the stators were assembled and only half of those had the copper wound. We could have assembled exactly the motors we want. In high the Mini has an inductance of 300uH and a resistance of 54mOhm, so doubling the Kv would have made it a real 15kw motor at just 72V.
I have plans where I could lock the motor torque to the swing arm (despite not being actually ON the swing arm), but the mechanics make it comparatively difficult for what will likely be marginal gains (the torque squat the motor is trying to educe in the swingarm is partially offset by the toqrue being transferred to the rear wheel, so the torque that will effect squat is about halved, or almost eliminated in 2nd). I'm looking at narrowing down the motor which might give me enough space to do that, but at this stage im not worrying about it, the common shaft on the swing arm should be enough.

Putting the motor on the swingarm also makes adding the pedals a bit of a headache vs the current design, though i might give it a bit more thought.... most of the itterations that used that ended up being too wide, or too difficult to get a good pedal chain line. If it it was an out-and-out motorbike, it'd be done already :P. Using a 160s would also make this easier, but i think this motor should be quieter and (possibly) more powerful. And I already own it too hahah.

Im considering leaving the motor sealed and just cutting some small fins into the already over-sized magnet backing steel and using some FF. The alluminium side cover would also be re-built with a far, far larger surface area both inside and out to aid cooling of a sealed motor. I'd also use a larger ID bearing, given the motor's not taking any significant weight (not being in a wheel any more) I can afford to use much smaller depth bearings, which will allow for 8+g phase wires with ease.

And yea im tossing up how much i actually modify the motor, it looks quite possible to turn it into a out-runner with only 1 supported side, so the other is open to the air and can be heat bridged directly to the frame for huge cooling... but its a lot of work that i might leave for a later iteration, given it should work fine with much simpler mods. And yea, its a real shame about the factory. I'd love to get my own stator and magnet ring and wind it myself, for a kv around 30. It'd be an absolute monster at that point, with no need for high voltage controllers.




drewjet wrote:Very nice. I like the idea of the stealths, and others, but hate the heavy hub motor. Looks like you have nailed it.

Are you running 2 chainlines? One for the motor and one for the pedals?
the pedals and motor both go to the swingarm axle, with 2 chains going from that axle back to the rear wheel, so the motor and pedals have the same ratio between them, and then they both have access to the 2 speed back to the rear wheel.
Basically the ratio between the pedals and the motor is constant, but they both have a 2 speed (with a difference of about 2.2:1) to the rear wheel. It means running 2 chains to the rear wheel, but simplifies it form trying to have 2 different gearboxes for each of the pedals and the motor.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by Hillhater » Tue Jan 26, 2016 8:58 pm

sn0wchyld wrote:
Hillhater wrote:Very nice bike,...but Is there really any point in keeping the pedals ?
No way will this ever pass as a "Bicycle" , and with 15kW or so, is the extra few watts of foot power worth the time or weight to build it in ?
For off road work , the extra ground clearance on reduced weight, it must be advantageous to just fit some pegs.?
Bike will still be used on road, with power limited appropriately, so yes. I also like the appeal of getting some more exercise, even if it makes jack difference to the power output offroad, and offers some level of redundancy. Just having pegs would make the build much easier, but i wouldn't have enough places to use it (and aus registration for custom stuff is a royal pita and wallet). Weight difference is marginal, only a couple of kg on a 40-50kg bike. Beauty of the bolt-together frame however is that such a change is pretty easy down the track :wink:
.
My point is , if you ride that bike on a publicly road, You will be noticed, but I doubt you will ever be able to win an argument that it is a legal Ebike if you are stopped by the law...no matter what "limiters" you build into it ( it would have to be "Pedalec" only, also remember).
Hopefully you have friendly, inquisitive cops over your way :lol:
....because they seize illegal bikes over here ! :shock:

And Does anyone with a powerful Ebike do any serious pedalling ...?
This forum owes its existence to Justin of ebikes.ca

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Tue Jan 26, 2016 11:55 pm

Hillhater wrote:
sn0wchyld wrote:
Hillhater wrote:Very nice bike,...but Is there really any point in keeping the pedals ?
No way will this ever pass as a "Bicycle" , and with 15kW or so, is the extra few watts of foot power worth the time or weight to build it in ?
For off road work , the extra ground clearance on reduced weight, it must be advantageous to just fit some pegs.?
Bike will still be used on road, with power limited appropriately, so yes. I also like the appeal of getting some more exercise, even if it makes jack difference to the power output offroad, and offers some level of redundancy. Just having pegs would make the build much easier, but i wouldn't have enough places to use it (and aus registration for custom stuff is a royal pita and wallet). Weight difference is marginal, only a couple of kg on a 40-50kg bike. Beauty of the bolt-together frame however is that such a change is pretty easy down the track :wink:
.
My point is , if you ride that bike on a publicly road, You will be noticed, but I doubt you will ever be able to win an argument that it is a legal Ebike if you are stopped by the law...no matter what "limiters" you build into it ( it would have to be "Pedalec" only, also remember).
Hopefully you have friendly, inquisitive cops over your way :lol:
....because they seize illegal bikes over here ! :shock:

And Does anyone with a powerful Ebike do any serious pedalling ...?
australia still has our old 'ungoverned' max of 200w. If limiting the controller counts as governing then technically any brushless motor has 0 ungoverned max output. I somehow doubt that would hold up, but the fact remains that it will have 200w max output, and that's in line with the 'spirit' of the law. And pedelec still isn't required for the 200w law. but yea, our laws make enjoying stuff a major pita sometimes, while doing little to nothing to improve public safety. But thats more a discussion that belongs in the toxic thread...

Pendragon has had his bike tested by the fuzz, its 'capable' of 6000w peaks, but it was in its legal mode when on road + confiscated so it passed fine and they gave it back soon after. I dont see why mine would be any different. I've been 'noticed' or rather had cops take 2 looks at my old norko builds, which were never very subtle for the most part, and never had an issue. I'm guessing because I never rode like a dickhead (well, not on the streets anyway :P ) so they never had a reason to bother me.

As to pedaling, absolutely, i do it all the time. helps range, keeps the motor cooler, keeps you fit(er) and lends support to the notion that the motor is there to assist not as the 'primary' form of propulsion. I generally only use a few 100 watts crusing anyway, so pedaling can have a big impact on your commuting power usage. Really I think we should adopt finlands or similars laws, where 1000w is fine with a drivers licence. I rather doubt it'll ever happen though, sadly.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by John in CR » Wed Jan 27, 2016 1:13 am

I have an extra stator from a motor I trusted to a machine shop who chucked it on a lathe and broke the magnets.

To really narrow it, once you gut the shifting mech there's space to move the bearing and get rid of the "knob" on the steel side. You'd have to weld in a new bearing support, but with steel it can be done without heat getting to the magnets if you're careful.

Heat moves too slowly through steel to count on getting much to the AL cover through that ring where the steel meets AL. Of course every little bit helps, and FF will take a nice bite. Will that get you to high power heat worry free?...I have my doubts, but it really depends on your gearing. 10-12kw geared for just 50-60kph for offroad should be low enough for low stress operation and extremely brief peak current demands even with your kind of hard riding.

I'd like to see how you could lock the motor axle to the swingarm without having it attached. Be careful not to underestimate the difference between torque squat and anti-squat with a bicycle suspension and your high pivot point.

it seems like you've really thought stuff through, so if you're sure my "watch out for's" are covered, then no need to type a time consuming response.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Wed Jan 27, 2016 8:45 am

John in CR wrote:I have an extra stator from a motor I trusted to a machine shop who chucked it on a lathe and broke the magnets.

To really narrow it, once you gut the shifting mech there's space to move the bearing and get rid of the "knob" on the steel side. You'd have to weld in a new bearing support, but with steel it can be done without heat getting to the magnets if you're careful.

Heat moves too slowly through steel to count on getting much to the AL cover through that ring where the steel meets AL. Of course every little bit helps, and FF will take a nice bite. Will that get you to high power heat worry free?...I have my doubts, but it really depends on your gearing. 10-12kw geared for just 50-60kph for offroad should be low enough for low stress operation and extremely brief peak current demands even with your kind of hard riding.

I'd like to see how you could lock the motor axle to the swingarm without having it attached. Be careful not to underestimate the difference between torque squat and anti-squat with a bicycle suspension and your high pivot point.

it seems like you've really thought stuff through, so if you're sure my "watch out for's" are covered, then no need to type a time consuming response.
2 speeds mate :P 1st is just 30km'h, the wheel is effectively 5.4 inches diamiter heheheh. it may be that its geared so low that heat is never an issue... but if it is i've at least got some ideas...

I'll do a basic mock up of the torque arm im talking about too when i get a chance, that'll explain it better than words can.

And yea, im thinking of just cutting off the magnet ring and making a new side cover for both sides... Again that said, im looking for 10kw peaks but really well less than half that continuous. the 2 speeds and some ferrofluid may make any further mods entirely unnecessary. The adaptto's got its automatic thermal rollback anyway so its even less of a issue. but if im building a heat bridge it'll be from the winding to the casing, not via the stator steel. A bit of work, but i imagine it'll make for one hell of a improvement in the cont. power rating.

The anti squat will be an interesting one, for sure. I doubt it, but it may be the case that I need to inversely couple the motors counter torque to the swingarm to nullify it. I doubt it'll come that far though....

and i always appricaite the feedback and poking at/pointing out potential holes in a design. better finding n fixing 'em now than try to after the thing's been built.

cheers.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by John in CR » Wed Jan 27, 2016 9:48 am

Cutting the steel side off is exactly how they broke my magnets. If you go to where it's flat at the perimeter the material is too thin for common hubbie orientation of the cover bolts, so the bolts have to be oriented radially like on RC outrunners. At the corner though it's nice and thick. With the brake drum removed the steel is thin enough that there's not a lot of weight to be lost, so doing it again I'd weld in a new bearing cup with the inner race just outside of access to the hole for the switching arm (to run one phase out that side.

I try to do as little to motors as possible to accomplish what I want rather than try to optimize. A bit of weight is meaningless to me, since I don't plan to go airborne, and to me your high pivot helps with heel and achilles clearance for the crank motion. For my trail riding I'll want a longer wheelbase than you probably would, so I can push the pivot high and rearward, making width almost a non-issue. That nets me more length for the battery compartment too.

I can't wait to see your results, so I hope the build is quicker than the plan. :mrgreen: Beware of my ailment, analysis paralysis.:lol:

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Wed Jan 27, 2016 4:42 pm

John in CR wrote:Cutting the steel side off is exactly how they broke my magnets. If you go to where it's flat at the perimeter the material is too thin for common hubbie orientation of the cover bolts, so the bolts have to be oriented radially like on RC outrunners. At the corner though it's nice and thick. With the brake drum removed the steel is thin enough that there's not a lot of weight to be lost, so doing it again I'd weld in a new bearing cup with the inner race just outside of access to the hole for the switching arm (to run one phase out that side.

I try to do as little to motors as possible to accomplish what I want rather than try to optimize. A bit of weight is meaningless to me, since I don't plan to go airborne, and to me your high pivot helps with heel and achilles clearance for the crank motion. For my trail riding I'll want a longer wheelbase than you probably would, so I can push the pivot high and rearward, making width almost a non-issue. That nets me more length for the battery compartment too.

I can't wait to see your results, so I hope the build is quicker than the plan. :mrgreen: Beware of my ailment, analysis paralysis.:lol:
my thought had been to use the drum break section as the part where radially mounted bolts could attach a new sidecover... Do you know what specifically caused the magnets to break? or did the guy just say 'they broke'?

cheers mate.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by John in CR » Thu Jan 28, 2016 2:00 am

I like the idea of using the root of the drum brake like that. First be sure to spin it up and use the brake to make sure it's interior is on a perfect center with the axle, since they're a welded on piece.

The guy put it on the lathe with the chuck jaws pressing out...teeth on the magnets. I wasn't there at the time. On another motor I had someone about to make the same mistake before I jumped in and said "Whoa, we can't do that." and explained why, which he still didn't seem to get. Now I'm paranoid about it.

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Thu Jan 28, 2016 5:19 am

John in CR wrote:I like the idea of using the root of the drum brake like that. First be sure to spin it up and use the brake to make sure it's interior is on a perfect center with the axle, since they're a welded on piece.

The guy put it on the lathe with the chuck jaws pressing out...teeth on the magnets. I wasn't there at the time. On another motor I had someone about to make the same mistake before I jumped in and said "Whoa, we can't do that." and explained why, which he still didn't seem to get. Now I'm paranoid about it.
at least the magnets breaking are from an obvious bad move - the pressure alone may have been enough to fracture them. I cant imagine it happening easily from clamping the outside - particularly with a 4 jaw chuck (spreads the load better). I'm guessing his lathe wasn't quite big enough for it though...

And yea good idea spinning it up and truing it first. will let you know how it goes :P

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Re: Sn0wchyld's 12kw custom frame mid drive

Post by sn0wchyld » Thu Mar 10, 2016 6:57 am

short update,

i wasn't happy where the current frame was going, mainly because it was proving very difficult to get the shock position to work well with the seat, and even then there wasn't much scope to lower the seat to allow for more body movement and positioning when riding...the basic shock attachment wasn't really doing it for me either. I basically went back to the drawing board and made a combination of the last 3 iterations. Main change is the shock has been moved below the swing arm, with some linkages to give it a progressive shock ratio from about 3.6 to about 2.4 - hopefully should work out well being the bike (particularly with me on it) is heavier than the standard downhill which usually goes from about 4 to 2.6ish in the more extreme cases (usually about 3.6 average)

Going to start designing the frame itself this long weekend (just been doing the basic sizing and positioning the last week or so). Bringing back the seat post swing arm from back in 2012 too, so the seat height can be adjusted on the fly, hopefully with a trigger mechanism that'll come later. Rise it up for street, drop it down for trials stuff!

here's the basic outline, more to come...
lowCOGlowshock.JPG
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