Custom frame for HUB MIDDRIVE_ fully

Finished Bike:

[youtube]N6I05G5x81Q[/youtube]
[youtube]9nxg4TUhBmM[/youtube]

Hello Guys,

My name is Jacob and I live in Vienna Austria. At home I have my workshop. Since my childhood I loved to build vehicles. The first builds were all with combustion engines like go-karts, trikes, gas powered bikes … the random fun- vehicles
During a project last year on the technical collage were I graduated, I realized how awesome E- vehicles could be. My team and I were developing a new intelligent force measuring system for electric bikes.

Here’s a video:
http://www.youtube.com/watch?v=CiYBd66nIM0

Well in fact I love to ride downhill or endure bikes, so I started to build a random hub motor converted e- bike.

I rode my bike about two years after I decided to build another NON HUB e- bike. The problem for me was that I live in a hilly area so the Motor braked the bike when I went downhill and didn’t accelerate enough when I went uphill.

Then I converted my Hardtail to a hub motor MID DRIVE.
I used a cheap 36V 500W gearless hub motor with reduced axle:

 
Here is the motor mount:


Later on I also added some steel bracing to the crank.

After some weeks of riding this bike I found out that the frame is flexing a lot and sometimes the chain jumped out in reason of that.
I made a lot of reaserch to find the “perfect” NON HUB frame but now I think there is nearly no frame that fits perfect for a NON HUB setup.

A really god one is shown in this topic from bzhwindtalker:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=37805&start=30
You were even pushing 200W through this!


Now I will start to construct and build my own frame. I bought a Centurion NO POGO as a geometry reference.


My plan is to make double down tube in two layers. So the motor is placed inside the frame. This should solve the problem that the force of the motor is pushing with a big force because of the leverage effect.
I’m still wondering how the frame of bzhwindtalker could withstand this huge force.

After my first sketches and measuring and calculating I started to make 3D CAD drawings



The first prototype of the frame will be made out of steel because it is easy to work on and also cheaper than aluminium
I will update my new constructions / drawings. It is very hard to calculate all those angles and notches on the tubes and i worked a long time to do the first drawings :?

But the basic drawings are there and I will continue soon.


Greetings from Austria
Jacob

Willkommen! Dieses projekt sehr interessant aussehen.

Thanks,

I made a little bit progress today. Here is where the motoro will be placed. I have not considered where the battery will be placed.



As in my previous build I will use my cheap 500W hubmotor and this 36V 10Ah (360Wh) Batteryy in the aluminium case.

I want to use the slide and lock mechanism of the battery system to remove it when I dont ride the bike.
I already constructed other parts of the frame. tho upper tube is alittle bit to long yet but geometry is now just a reference:



Any suggestions where would be a good place for the battery?

... jacob

jackjetful said:

Hello Guys,

My name is Jacob and I live in Vienna Austria. At home I have my workshop. Since my childhood I loved to build vehicles. The first builds were all with combustion engines like go-karts, trikes, gas powered bikes … the random fun- vehicles
During a project last year on the technical collage were I graduated, I realized how awesome E- vehicles could be. My team and I were developing a new intelligent force measuring system for electric bikes.

Here’s a video:
http://www.youtube.com/watch?v=CiYBd66nIM0

Well in fact I love to ride downhill or endure bikes, so I started to build a random hub motor converted e- bike.

I rode my bike about two years after I decided to build another NON HUB e- bike. The problem for me was that I live in a hilly area so the Motor braked the bike when I went downhill and didn’t accelerate enough when I went uphill.

Then I converted my Hardtail to a hub motor MID DRIVE.
I used a cheap 36V 500W gearless hub motor with reduced axle:
View attachment 5
 
Here is the motor mount:
View attachment 4

Later on I also added some steel bracing to the crank.
View attachment 3
After some weeks of riding this bike I found out that the frame is flexing a lot and sometimes the chain jumped out in reason of that.
I made a lot of reaserch to find the “perfect” NON HUB frame but now I think there is nearly no frame that fits perfect for a NON HUB setup.

A really god one is shown in this topic from bzhwindtalker:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=37805&start=30
You were even pushing 200W through this!


Now I will start to construct and build my own frame. I bought a Centurion NO POGO as a geometry reference.

View attachment 2
My plan is to make double down tube in two layers. So the motor is placed inside the frame. This should solve the problem that the force of the motor is pushing with a big force because of the leverage effect.
I’m still wondering how the frame of bzhwindtalker could withstand this huge force.

After my first sketches and measuring and calculating I started to make 3D CAD drawings
View attachment 1


The first prototype of the frame will be made out of steel because it is easy to work on and also cheaper than aluminium
I will update my new constructions / drawings. It is very hard to calculate all those angles and notches on the tubes and i worked a long time to do the first drawings :?

But the basic drawings are there and I will continue soon.


Greetings from Austria
Jacob

Click to expand...

Go to 'here' on the shead haven't seen he rest and i'm subscribing now so this thread!

All the best buddy not a race to build it take it steady and this will be a pearler i hope!!

KiM

also read http://endless-sphere.com/forums/viewtopic.php?f=28&t=37805&start=100#p569072

ok yeah, I red the topic.
I think there is nearly no normal bike frame which would be suitable for high powered mid drives.

After his frame filed he just upgraded his it but in long time use i think the whole frame could collapse (weldings, thin tubes).


I still don't find a solution where i could place the battery. The problem is that the motor needs a lot of space. So ther is not much place left. I defenitly want to make the battery removable so the best place would be on the down tubes. But the upper tube would make it impossible to slide the battery out of the frame.

Looks like the fork angle is very slack in the last drawing unless its only going to be used for street riding. How about having the top tube more of a "V" shape into it. Slide the battery way up closer to the head tube area to also clear it from the front wheels suspension travel. Also if you are still shopping for a different battery pack the cell man 48v 14ah has a nice size to it that looks shorter than your drawing in proportions. Also with the orientation of your batery in the last rendering if you flip a cell man 14ah on its side it is not too wide to sit comfortable between the legs, even up high in the bike.The 14ah may sit OK with its widest part sitting flat and slide it closer to the head tube and clear of the front wheel.
The edit to your drawing attached here shows what I am trying to describe with the red rectangle showing battery placement and the other red lines showing posible changes to tube layout.

Good luck. I am following your build with interest.

Thanks for the nice imput. I made new calculations and measurings on the Centurion frame. I will copy it's geometry.

I would like to have a low center of gravity. So the battery should be as low as possible. The "V" shape on the top tube would be a great solution but I decided to make the frame in a different way. These are my latest drawings:
View attachment 2

All tube pieces on the frame will be straight which means that I have to weld a lot but I think it would be easyer ( also becaus I have no tube bender )

The top tube will be cut and two steel plates will be used to connect the top- tube to the fork- tube.


Here are the steel plates. The idea is, that the battery (a good choice would also be the 48V setup ) will be placed on the double-down tubes. I think this is the best way (for stbility reasons and to have a low sitting battery). So on the battery will be slideableover the handlebar.


The plates will be hard to build but I think this is the best solution. Geometry of them is not perfect now. If the handle bar will be mointed it would be imposslible to slide the battery out; but I will work on them next. They will also be heavy (5mm thick mid steel )

That looks like it could work for you. One more idea I was thinking if you had that junction of the side plates etc (where you plan to attach the top of the seat tube to the top tube) a little lower down on the sloping down tube, like say even mid way down the down tube length may be better. I think with your design things would still be strong enough with this slight modification. I only recommend this as I think it may look better but mostly because it will give you more stand over room if you are using it on the trails. I have found once a bike gets a bit top heavy with the electric stuff on board the extra stand over height is nice to have.

jackjetful said:

The problem is that the motor needs a lot of space. So ther is not much place left.

Click to expand...

Hi Jack,

Taking the flanges off of the motor would gain you a bit.

Hello Miles,

Yeah I also thought of that but I heared this could impact on the stability of the motor housing.
I have still not decided if I raly use the 500W motor. The first prototype of the whole frame will be mad put of steel. So it will be very heavy ... maybe 500W won't be enough to build a "well" powered e- bike.

I think you are missing one critical part of the equation.
Why design a frame around a motor like this? a hub motor is the heaviest and one of the least efficient ways to design a mid drive.

You need to start thinking about dual or triple reduction drives of vastly lighter and more efficient motors.

It all depends what you want to have... a very powerful, light but very noisy RC-Drive ... or a heavy but qiet and more efficient HUB-middrive.

I decided to build my bike wirh a hub motor as a middrive because I think it is a better solution for long time use. I already built a bmx with an RC motor and the transmission was very lout and after a short time I recognized the heavy wear on the setup.

BUT: If my frame will work fine I also plan to built in a RC- Drive. So im going to design it for various motor types (the down tubes give me a lot of space ) maybe the second version will be bade out of aluminium with an Cyclone motor built in.

.. Jacob

mid drives are nice but i think rc are under powered and over complicated for ebikes. although a hub might be a fairly affordable and efficient to run, why not use a more powerful motor as a mid drive like john's

way more copper = better power and efficiency



http://endless-sphere.com/forums/viewtopic.php?f=31&t=40859

http://endless-sphere.com/forums/viewtopic.php?f=28&t=16807&p=255181&hilit=big+ass+outrunner#p255181

Hi,

My frame will designed for several Motors. Previosly I thought to built in a Crystalyte Motor but the first prototype will be powerd with my "small" 4kg hub.

There are plenty of motors between the RC world and the hub world.
RC motors can be super quiet with the right controller and a belt drive primary.

Hub motors hang out in the 79-86% efficiency zone. RC and low kV chain drive motors hang out in the 86-97% efficiency zone. The hub you are going to use is in the low 80% efficiency range.

If you have heavy wear on a setup, you have used gears with too small of teeth and/or the wrong pitch. An RC setup should last a very long time.

jackjetful said:

It all depends what you want to have... a very powerful, light but very noisy RC-Drive ... or a heavy but qiet and more efficient HUB-middrive.

I decided to build my bike wirh a hub motor as a middrive because I think it is a better solution for long time use. I already built a bmx with an RC motor and the transmission was very lout and after a short time I recognized the heavy wear on the setup.

BUT: If my frame will work fine I also plan to built in a RC- Drive. So im going to design it for various motor types (the down tubes give me a lot of space ) maybe the second version will be bade out of aluminium with an Cyclone motor built in.

.. Jacob

Click to expand...

"Hub motors hang out in the 79-86% efficiency zone. RC and low kV chain drive motors hang out in the 86-97% efficiency zone. The hub you are going to use is in the low 80% efficiency range.

If you have heavy wear on a setup, you have used gears with too small of teeth and/or the wrong pitch. An RC setup should last a very long time.
"

But there is a difference in one chain to my freewheel crank and a whole second transmittion to reduce the higk KV of RC motors and this could also cost eficiency!? .. I don't want to speak in a bad way abot RC drives. I also think tey are awesome ... but for my use it is much more easy to use my cheap hub.

If you have a lot of time, cnc machines and enough money I think a well constructed RC drive ist the best.

Back to frame construction:


I made the last Pro Engineer drawings you saw yesterday.

So today there has also been some progress:


Here is where the rear shock absorber is mounted. the plates are also used to provide the stability for the seat- tube.


I nearly needed the whole day to redesign the two side- plates.
Now they look like this:

You can see the handle bar on the front. It is now possible to slide the battery over the andle bar and remove/ charge it.
.

The top tube is now a little bit higher and the side plates bigger.
The wholes inside them will be used to weld it onto the tubes behind them.

I hope this will be solid enough.

jackjetful said:

But there is a difference in one chain to my freewheel crank and a whole second transmittion to reduce the higk KV of RC motors and this could also cost eficiency!? .. I don't want to speak in a bad way abot RC drives. I also think tey are awesome ... but for my use it is much more easy to use my cheap hub.

If you have a lot of time, cnc machines and enough money I think a well constructed RC drive ist the best.

Click to expand...

If you use a belt drive setup for the primary stage, it can be very efficient.
There are about a dozen ~70kV motors out there which can be set up with a single 5:1-6:1 stage, and still be light and simple to set up.

AND i like planetary gears the most. in fact this motor is quite large and it limits your frame building liberties. why not use a smaller motor and spin it faster? A middrive can not regen, so there is no need to keep speeds very low. You just have to know how many stages of motor->crank reduction you want. Is it one, two or three? This is what decides on the motor you will chose. If this number is one, you should get friends with your motors dimensions. Otherwise, rethink

There are about a dozen ~70kV motors out there which can be set up with a single 5:1-6:1 stage, and still be light and simple to set up.

Click to expand...

the bafang BPM and MAC come with 6:1 reduction if converted. It is has even lower KV. As I said, you cannot use regen in a middrive. So why not use a converted geared hub? Is low noise really so important in a DownHill bike?

I don't want to hi jack this thread getting side tracked on noise but for me its a huge huge deal. I feel the whole point of an electric bike is the quiet.

The friendly greeting you get when riding around is in my opinion because of a quiet bike. I even think the wind noise at speeds of over 25mph is too noisy. I am in the minority I am sure on this one, but for me its all about the quiet. I have had some unbelievable times on the trail hearing the birds chirping away and the grass under the tires, there is nothing like it and being able to climb steep hills is the real bonus.

Why even bother with electric if it makes noise? It would make as much sense to just plop a stinky gas motor on board and be done with it.

The MAC hub is 5:1, i am not sure about the bafang.
The KV ultimately is low after the reduction, yes, just like a DD hub.
However the efficiency of both of those motors is in the 80-82% range, and they are still a bit heavy.

This would be better than the larger DD hub though, yes.

All i'm saying is that if you're building a custom frame from the ground up, building a sweet dual reduction drive into it could be done about 5x easier than on any other premade frame. It could be made very quiet and efficient by using belts.

Just a suggestion is all.

crossbreak said:

the bafang BPM and MAC come with 6:1 reduction if converted. It is has even lower KV. As I said, you cannot use regen in a middrive. So why not use a converted geared hub? Is low noise really so important in a DownHill bike?

Click to expand...

neptronix said:

a hub motor is the heaviest and one of the least efficient ways to design a mid drive.

Click to expand...

It's also the quietest, simplest, lowest in maintenance, and most reliable. There is nothing that makes sense about a triple reduction once you make realistic assessments of the efficiency and maintenance costs of each stage. Now that you can get hub motors of well over 80% peak efficiency, you can't significantly beat them in the real world by using multiple haphazardly engineered reduction stages.

Motor mass, like structural mass, buys you fault tolerance and a wider operating envelope. It takes a much, much longer duration overload to burn up a 1000W hub motor than to do the same to a 1000W RC outrunner. So while the hub motor may be heavier, it's not simply dead weight.

Chalo said:

Now that you can get hub motors of well over 80% peak efficiency, you can't significantly beat them in the real world by using multiple haphazardly engineered reduction stages.

Click to expand...

There are not many available, the ones that are high efficiency are very large and very heavy. Then there is the falco hub motor - if you can find it at a non-ludicrous price. But i believe that you end up in proprietary controller land then..

Reduction stages don't have to be haphazardly engineered , look at the awesomeness that is the ecospeed mid drive and optibike's mid drives.

Chalo said:

Motor mass, like structural mass, buys you fault tolerance and a wider operating envelope. It takes a much, much longer duration overload to burn up a 1000W hub motor than to do the same to a 1000W RC outrunner. So while the hub motor may be heavier, it's not simply dead weight.

Click to expand...

Yes, it does take a longer time since you have more thermal mass, but the overheat happens eventually and over the long run, the continuous power handling of most hub motors ( cept the 40mm-50mm statored ones which weigh 18-32lbs ) is pretty poor due to the low RPM they operate and the fact that they are sealed.

A RC outrunner with a fan on it changes everything, one example is my transmagnetics motor - 3-4kw output continuous but only 11lbs, thanks to the fan. but i'm not suggesting a RC motor here at all because they're loud and difficult to control. I'm talking about the half dozen excellent ~70kv motors out there which can turn into wonderful light mid drive setups with the right frame.

[youtube]PcyKhL6sb4A[/youtube]

But in terms of RC motors, here is a 5 pound astro motor with a fan on it hitting 66mph. It's the best mid drive setup i have ever seen on this forum.