Mid-Drive 80100 : my project !

Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
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Rikobonito   100 W

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Re: Specs Performance for 80-100 motor ?

Post by Rikobonito » Feb 18 2018 11:28am

:shock: wow, insane "pushing it to the limite" test !! Thanks for your feedback byte. Cool powerfull build by the way.
So adding some "S" could limite the max amps so the heating.
At 1st like you I want to pass all the power to the left side of the wheel. Your 11kW is like what, almost 15HP ?!
Its not possible to put safetly that power to the right side ?? (Or alf at least :D ) Cause the concept is pretty cool, we should help the motor according to the pedal cadence of the terrain !

My main issu was that I got less than you on the rear break disk:
Image
Image
And I can't move the disk or break mount, it already againts the frame...

Sorry for the off topic Matt, so used this motor with your hight ratio and switchable capacity, the motor will heat consume less for a better no stress mode.
Maybe a 8085 is as good in your concept configuration...
my little blog with e-sk8, e-Cruiser, e-pintail, e-MTBoard, e-Dirt Scooter and others builds
... I wish also an e-MTBike soon !! :v: Thanks DIY Power community :wink:

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Ecyclist   1 kW

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Re: Specs Performance for 80-100 motor ?

Post by Ecyclist » Feb 19 2018 4:02pm

I build something of that kind. I used 18650 cells with 10s6p config. , VESC and 6374 outrunner. I'm getting 50 km/h and have no problems.
In a couple of weeks I will change motor to 80mm and controller to get up to 60 km/h and a little more respect. :lol:
I think that the controller is the most important part of your build. If you get it wrong you will have nothing but problems.
63 or 80 mm APS motor will do fine. Do you know what controller you are going to use?
Avian.JPG
Avian
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Last edited by Ecyclist on Feb 19 2018 9:56pm, edited 2 times in total.

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Rikobonito   100 W

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Re: Specs Performance for 80-100 motor ?

Post by Rikobonito » Feb 19 2018 9:04pm

Hey Ecyclist ! So glad you came comment that cause I don't already take time to congrat' you, but know it, your build is insane !!! :P I cross many time some pic of you on esk8builder forum ;) love what you do !! Its the way I want to go too yes !

I would start with 6374 130kv sensored with Focbox, like you !.. And also already got 8085 (already used but swappable after hight 170kv.., the 8072 is not at good kv at all) and vesc6 or ESCape to go with (playing with esk8/emtboard immedialty make to have many parts..).
Actualy the v6 sensored under FOC mode is the best thing I ever ride !!! The feeling is just so good ... I know it will finish with something like that too here :mrgreen:
As we could also see some VESC-like for 18s 200Amps ... The perfect ride is possible so :idea: (I'm a LMX fan, so the ultim plan is an almost no pedal build - just in case of no juice).

I'm just sad/worry about to lost my 11 gears on the rear or can't use them all (cause here it's not flat, plus I do a lot of terrible trail ... the limite is actualy the back wheels spinnin the ground without e-power) or the part I need to change.
I know I want to do it your way or like Matt plan ... just scared cause I know nothing about bike, standard size, name etc. but I already learn a bit here and will do more.
my little blog with e-sk8, e-Cruiser, e-pintail, e-MTBoard, e-Dirt Scooter and others builds
... I wish also an e-MTBike soon !! :v: Thanks DIY Power community :wink:

Matt_92   100 mW

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Re: Specs Performance for 80-100 motor ?

Post by Matt_92 » Feb 20 2018 9:35am

Hey everybody, don't have time to reply each posts... but great compact reducer Avian ! is it an home made reducer ? do you know its efficiency ? I like the idea to have a dismontable 18650 battery pack, you can replace "easily" a cell if needed...

I like too the LMX (frenchy), but the motor is not so powered than the 80100 but I think that its efficiency is better...
...from France, sorry for my english :oops:

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Ecyclist   1 kW

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Re: Specs Performance for 80-100 motor ?

Post by Ecyclist » Feb 20 2018 1:49pm

It's great to see Esc8 forum enthusiasm moving to ES. We definitely need more of that.
I'm happy that I'm not the only one who thinks that VESC is a good, soon to be great, option for a LMX.
Until now, I've been running my bike on VESC 4.12, but I have ESCape from Stewii coming my way and I'm waiting for ESK8 1.1 to be available so I can test it as well.
I've been running hall wired throttle and ACKMANIAC-ESC Monitor on the same UART connector without any drama. I might be the first one doing that. I just hope that someone will develop app for VESC for android that looks like the one from Power Velocity.
Power Velocity.jpg
Power Velocity.jpg (16.68 KiB) Viewed 1309 times
I can always dream.
I built the transmission myself, and it is as efficient as two stage belt/chain type, but takes only 1/3 of the space.

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Re: Specs Performance for 80-100 motor ?

Post by Matt_92 » Feb 21 2018 9:46am

Ecyclist wrote:
Feb 20 2018 1:49pm
I built the transmission myself, and it is as efficient as two stage belt/chain type, but takes only 1/3 of the space.
Do you plane to create an more strong reducer for the 80100 ? can this reducer pass the 80100 torque ? What is the ratio ? How does it cost to you ? do you have machinery for mcahining ?

Is it the same reduction process than that ? :
https://www.youtube.com/watch?v=8DYuSvJ-CUw

Sure that it's really more compact that with belt/chain !

Great job ! :wink:
...from France, sorry for my english :oops:

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Ecyclist   1 kW

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Re: Specs Performance for 80-100 motor ?

Post by Ecyclist » Feb 21 2018 6:57pm

My reducer is already strong enough for 80mm motor, but I'm planning on a couple changes to make it better. At this point the ratio is 19:1. I machined it all excluding bearings and pins. I built other one that is 16:1.
You can visit my thread for details.

Yes, my reducer is based on the same principle, but is much better.
My reducer at no load is using about 100 W of power.
Tangent is using $700 Astro Flight ,very efficient motor, and is using at no load about 350 W.
This is a clear sign that something is wrong with Tangent. Can you guess what?

Obviously, you have technical skills and you should have no problems with building high quality and compact belt reducer.
The most important part for you will be to make it structurally rigid and running true.
I reworked GNG belt drive kit and have it still running strong on my wife's e-bike.
I'm looking forward to seeing your build developing.
Good luck.

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Re: Specs Performance for 80-100 motor ?

Post by Matt_92 » Feb 22 2018 7:38am

Thanks Ecyclist for your encouragaments :)

But if you plane to "commercialize" your reducer, I could be interested :wink:
I have to confess, that I prefere have a small reducer as yours that a multi belt drive reducer, in terms of space, but I know too that it's a compromise between cost/space...

Great job ! :wink:
...from France, sorry for my english :oops:

ScooterMan101   1 MW

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Re: Specs Performance for 80-100 motor ?

Post by ScooterMan101 » Feb 22 2018 12:04pm

Matt_92

I see a picture in one of your posts of a full suspension bike that is single pivot , with the swing arm going up and over the crankset/chainrings. it looks much like the Santa Cruz Bantam / Butcher / Bullit / Superlight, and other Bikes that have the same design.
And
You say you want to build your e-bike for the purpose of going to work, and you want to ride a sustained speed of at least 50 kph.
And
You want to do all that for around 300 Euros.

300 Euros will not get you a system with a reduction drive, ( I have been pricing a system for my bike as well )
I am wanting the same performance as you, however even more/faster speed for me .

I have looked at and want one of the great designs that are new like the the one from Ecyclist / Mike at LightningRod's / Tangent / PaulD

However
I am wondering ... for those of us that only need one speed , ( Fast ) and have the type of bike frame that will accept a large outer chainring, I am thinking that perhaps we can eliminate a reduction between the motor and the crank/chainring by ...
having a very large chainring made along with a very low KV ( 50kv or so ) Motor ?

Par Exapmle : Have a very large chainring custom machined that goes on the outer side of the existing chainring by using spacers to put it outboard of the existing chainring , by a good 4 mm or so .
Then just connect the motor directly to that large outer chainring .

And not even use a freewheel crankset since the bike is for using on the Road for Commuting or Traveling longer out of city distances .
It is ok to ..not use the motor when freewheeling to a stop and when going down hill.

Anyone wanting to use a bike off road on the trails , and anyone with a bike frame that will Not accept a large chainring , Will have to get a reduction system like one from Dave ( Tangent ) / Mike ( LightingRod's ) / Ecyclist / or PaulD .
However
For someone like me, and perhaps you who only wants to use a bike for higher speeds just on the road for commuting / traveling , the Idea I list above might just work fine. Then get a different bike with a reduction system for off road use.


Low KV motor with very large chainring with lower voltage battery 6/5/4 s pack , ( Note you can Parallel many 6, 5 or 4 s packs together to get the total watt hour pack you want for the distance you want to go )

I have been thinking about that combo on a good quality Road Bike for Pro Peloton type speeds for a while now. With the Right style of Full Suspension MTB like the single pivot design with the swing arm coming up and over the crankset you could make it work as well, for Road Use .
Last edited by ScooterMan101 on Feb 22 2018 3:12pm, edited 2 times in total.
My first conversion ...

https://endless-sphere.com/forums/viewt ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

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Ecyclist   1 kW

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Re: Specs Performance for 80-100 motor ?

Post by Ecyclist » Feb 22 2018 3:00pm

I just hope that we all build our own stuff. It is more fun and rewarding. Plus, it helps to push an envelope a little farther.
Saying all that, if you're only after single speed for flat road, then the hub motor is the way to go. Simple, inexpensive and effective.
For roads with some hills, two speed hub is a very good choice. I normally don't recommend Chinese products, but on rare occasion, I do.
In that case, I will go with Xiongda 2-speed hub motors. I installed it on my son's trike. You will get a lot of value for $250 shipping included.
Xiongda 2 speed motor on Gekko 1.JPG
Xiongda 2 speed motor on Gekko 1.JPG (196.89 KiB) Viewed 1225 times

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Re: Specs Performance for 80-100 motor ?

Post by ScooterMan101 » Feb 22 2018 3:38pm

Ecyclist,

I agree that for simplicity and low cost the Hub Motor is the best for most people, ( I have a 6T Mac Rear Motor that runs great at up to 25 mph / 42 kph , and it will go up hills up to around 8 % grade, but it prefers only up to around 5
% grades ) it will go 50 kph , but to make it go that I have to pump more amps through it than I like, that is not something I want to do for many miles continuously because of high battery draw and heating of the motor , at 50 kph and over 30 amps to 35 amps at 52 vols needed to do so ...I question how long the motor would last .

It looks like Matt_92 has to go up in altitude 130 meters on his route , if the % of slope is high enough a high speed hub motor is not the best for him. It's possible but he would have to use a very heavy DD Hub Motor and then he would have a very high cost of big battery pack needed in order to run it at the speeds he wants.

I looked into getting a Xiongda for myself in the past ,
However

The Xiongda will not get up to the speeds some of us want, and it is very wide , people have to spread out the rear triangle of their bike in order to make it fit, I will not do that to any of my bikes.
so
for those two reasons it would not work for what he , and I as well want to do , too bad cause I think a stronger/bigger version of it would be good as long as a custom frame was also offered to buy in order to fit it properly into a frame.

I look forward to all the new development work that you and others are doing with RC Motors.
My first conversion ...

https://endless-sphere.com/forums/viewt ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

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Ecyclist   1 kW

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Re: Specs Performance for 80-100 motor ?

Post by Ecyclist » Feb 22 2018 7:26pm

Xiongda 2-speed will fit in standard 135 mm rear dropouts without any modifications. That option has been available for at least a year.
That is exactly what I installed on my son's brand new trike. However the max rear gearing is 6-speed freewheel. With three up front, his total is 18 speed. He will have to live with that. :D
Plenty of guys forced larger 145 mm motor into 135 mm dropouts without a problem, but I didn't see the point in doing that. Kind of goes against my grain. That small (250W and 730W peak) motor will get you up a very steep hill with half the speed on the low gear. Top speed is 35 kph (22 mph).
It is not a neck breaking speed, but perfectly fine for a reasonable person or European regulations. The only problem is how many of us want to be reasonable. :mrgreen: I guess my son is because he is happier than shit with his new toy. I kind of like riding that trike as well. It sort of feels like being in amusement park.

Matt_92   100 mW

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Re: Specs Performance for 80-100 motor ?

Post by Matt_92 » Feb 23 2018 9:06am

Hello everybody :D

I don't plane to use it off-road
We are speaking about a potential 7000w mid drive, not EC 250w.... :mrgreen:

Just to have an idea of the price, in this case with 70kv motor (inclued) and one stage belt drive system :
(I just made a copy/adaptation of the 2 stages belt drive system, for 70kv motor with 18/60T pulleys)

-Aluminum pipe Ø10x2mm for spacer : 15€/m
-Threaded rod M6 : 10€/m
-(16x) locked nuts M6 : 8€
-(3x) laser cut 3mm thickness steel sheet : 80€ about (I suppose less)
TOTAL : 113€
transmission-primaire_c80100_22b.jpg
transmission-primaire_c80100_22b.jpg (26.26 KiB) Viewed 1175 times

-C80100 APS 70kv : 160€
-Pulley HTD5M-20 18T : 12€
-Pulley HTD5M-20 80T : 70€ (I suppose, seen on customized Aliexpress prices)
-Belt HTD5M : 20€
-Free wheel 14T 3/4" : 35€
-Keyed shaft 3/4" : 25€/m
-(x2) Circlips 3/4" : 4€
-(x2) Flanged bearings 1-3/8"OD, 3/4"ID : 10€
-(x3) bearings (for belt tensioner) 24x8x8 : 9€
TOTAL : 345€
transmission-primaire_c80100_23b.jpg
transmission-primaire_c80100_23b.jpg (30.85 KiB) Viewed 1175 times

-Crank + free wheel + chain : 80€
-Clamps (to attach to the frame) : 10€
TOTAL : 90€
transmission-primaire_c80100_24b.jpg
transmission-primaire_c80100_24b.jpg (36.69 KiB) Viewed 1175 times

TOTAL 548€ :mrgreen:

You're right Ecyclist, difficult to do less than 300€ :idea:
Last edited by Matt_92 on Feb 23 2018 3:59pm, edited 1 time in total.
...from France, sorry for my english :oops:

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Re: Specs Performance for 80-100 motor ?

Post by Matt_92 » Feb 23 2018 9:27am

Visual comparative between 1 stage and 2 stage belt drive :

(bottom brackets are 68mm standards, not large)
transmission-primaire_c80100_25b.jpg
transmission-primaire_c80100_25b.jpg (50.64 KiB) Viewed 1171 times
Last edited by Matt_92 on Feb 23 2018 4:14pm, edited 2 times in total.
...from France, sorry for my english :oops:

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Re: Specs Performance for 80-100 motor ?

Post by DanGT86 » Feb 23 2018 10:21am

Obviously the single stage of reduction would be ideal. But you have to remember that the power of the motor is closer to 7kw at 7000rpm or more. If you go with a lower kv motor you have to feed it lots of volts to get the rpm back up. If you want close to 7kw you are pretty much stuck with 7-8k rpm for an 80100. The pedal drivetrain being overdrive means you need tons of reduction to get from 7k rpm to about 100rpm at the crank.

Assuming you want 7kw:
If you are running an 18 tooth freewheel and a 40 tooth chainring then you need to use 2 stages of 18:80 tooth belts just to get you down to 150rpm at the pedals.

Also the 2nd stage of belt reduction is going to have lots more load on it than the first stage. Its handling the same power but at less than 1/4 of the speed. If you look at the gates belt selection charts for power handling and belt choice you will probably find that amount of power at 1500rpm is beyond the recommended range for the 5mm belt.

Usually each reduction needs to be stronger than the one before it. You may need to use 8mm pitch belt for the second stage or a considerably wider 5mm.

Hope that makes sense. The models look great. Keep up the design work!

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Re: Specs Performance for 80-100 motor ?

Post by ScooterMan101 » Feb 23 2018 12:40pm

Matt_92

548 Euro"s , or more is like what I was thinking it would at least cost with a reduction .

I did not see a listing of the cost of a controller , Vesc's are 100 and more Euro's each

So now it is really 650-700 Euro's , still good as the one's I would like to buy , that are made here on the West Cost of the U.S. cost that amount or a little more ( factoring in the exchange rate ).

For me and many others the hose clamps / hose clamp mount would most likely need to have a slightly different design,
I do not have a round down tube, and most people with a full suspension MTB do not have round down tubes.

What do you think would be a low cost way of having the clamping force's distributed over a larger area ?

I am thinking about a block of Delrin that is machined on the inside to match the frame and with grooved outer in order for the hose clamp to wrap as far around the downtube/delrin as much as possible . Think there is a cheaper solution ?

DanGT86 is making a case for using 2 stage reduction , However I think it would be best to buy a motor with a lower KV in the first place this would make your life/design easier I would think.
Also
Regarding reductions , 100 rpm cadence at the cranks is too fast for my legs and cardiovascular system. 80 rpm and down to 70 rpm is more in the comfort zone. As we age we need to keep the Heart Rate down lower and the Cardiovascular System working with less stress.
My first conversion ...

https://endless-sphere.com/forums/viewt ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

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DanGT86   10 kW

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Re: Specs Performance for 80-100 motor ?

Post by DanGT86 » Feb 23 2018 1:02pm

ScooterMan101 wrote:
Feb 23 2018 12:40pm

I am thinking about a block of Delrin that is machined on the inside to match the frame and with grooved outer in order for the hose clamp to wrap as far around the downtube/delrin as much as possible . Think there is a cheaper solution ?

DanGT86 is making a case for using 2 stage reduction , However I think it would be best to buy a motor with a lower KV in the first place this would make your life/design easier I would think.
Lower motor RPM is always easier but it cuts the power handling a lot. Just keep that in mind. You can't cheat the physics. The miracle power of these tiny motors is from the rpm. At any given time the load on the motor is low because there are so many RPM to share that load for a given power. If you slow them down then the load and the current go up really fast and you have a nice melted motor on your hands. The RPM is why 3kw hubs weigh 10kg and 3kw rc motors are only 2kg.

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Re: Specs Performance for 80-100 motor ?

Post by Matt_92 » Feb 23 2018 2:19pm

DanGT86, you're totally right, for the 2 stages belts drive, about the pitch of the second belt ! I didn't find (or not good searched..) charts with Power/RPM - HTD5M/HTD8M for 20mm wide belt... but I thought about it !

My thought on this is :

-1st stage : not enough resistant torque, it's ok for HTD5M, for sure !
-2nd stage : less RPM, same Power, so more torque ! If I suppose have a resistant max power during a very short time, I suppose it could be ok during all the rest of the ride, but yes it could be a problem ?! After, I reassure myself by telling myself that I never saw HTD8M mid drive (or only one but with very higher power)....

After, for the choice of 1 stage or 2 stage, depending of the KV... we have to imagine at same power :

-Diesel engine (as a low kv) : low RPM, big torque, low ratio
-Gas engine (as a high kv) : high RPM, low torque, high ratio

Remember that if the reducer, reduce the RPM, it improve the torque, and vice versa...

Mechanical Power = RPM x Torque
Electrical Power = Volts x Amps

The question is : what is the most efficient choice, between : 70kv/1 stage Vs 130kv/2 stages ? Electrical efficiency Vs Mechanical efficiency ? I keep in my mind that Alien Power System always told me that efficiency 130kv is better than 70kv, but he never gave me the charts...

I know that I can suppose a loss of 3% by belt drive stage....
But I don't know what is most efficiency motor at 44v between 70kv vs 130kv ? maybe 85% vs 95% ? I really don't know !

What I think I have seen too, is that it's more complicated to manage a low kv motor ? It could create some trouble at very low RPM ?

I plan to use a low cost Flier controller like that (about 150€/200A and 200€/300A):
Controller.jpg
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...from France, sorry for my english :oops:

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DanGT86   10 kW

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Re: Specs Performance for 80-100 motor ?

Post by DanGT86 » Feb 23 2018 10:13pm

I found a Gates Belt selection HP chart once. I'll look for it.

I think in your case you are stuck with 2 reduction stages before the chainring. You want as much motor rpm as possible so even at 16s with the 70kv you are going to need 35:1 reduction to get a reasonable pedal cadence of 100rpm or less. 16s battery is 60v.

So 60v x 70kv=4200
Loaded you get about 85% of that. 4200 x .85=3570rpm
HTD belt 18:80 tooth= 803rpm at the jackshaft.
13 tooth mini bmx freewheel driving a giant 60 tooth chainring gets you to 803 x 13/80=130rpm pedal cadence

In this case the motor is spinning too slow to make anywhere near 6-7kw and the bike chain reduction is not ideal because of the 13tooth freewheel driver. So the worst case scenario for the motor and chain still has you pedaling at an unrealistic 130rpm and that is with a giant and rare chainring.

If you are dumping heat into that small motor trying to make power at low rpm its going to be way less efficient overall than a setup that allows it to spin at 6-7k rpm. Try to stop thinking about different windings and just target the ideal speed for that motor size to make its rated power. With this motor that speed is over 6000rpm.

Generally, lower kv motors are easier on controllers than higher kv motors. I may be getting that confused because WYE tends to be easier to drive than DELTA and is lower kv for the same windings. So Im not sure if its the KV or the winding termination that makes it easier on the controller.

Also, you can buy a common 130kv motor which will likely be terminated in Delta. You can separate the 3 phases into 6 and re-terminate it in WYE. This will drop it to 80kv and make it slightly easier on controllers. So if you wanted to try both the single and double stage reductions you could do it all with the same motor. While you are in there add a temp sensor. This is the best thing to do when experimenting with an RC motor because when these small motors are not happy they let you know pretty quickly in the form of heat.

Matt_92   100 mW

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Re: Specs Performance for 80-100 motor ?

Post by Matt_92 » Feb 27 2018 9:29am

DanGT86 wrote:
Feb 23 2018 10:13pm
Loaded you get about 85% of that. 4200 x .85=3570rpm
Hey dan, you mean that when loaded, I have to consider 15% of losses between loaded/not loaded ?

Here is my brainstorming to calculate the kv following speed, crank rpm, and battery :

If I consider 50km/h with a 26-1.00 tyre = 436 rpm at the rear wheel
If I consider last chainring stage ratio with derailleur 42/11 = 3.8:1
It results : 436/3.8 = 115 rpm at the crankset
If I consider a 2 stages mid drive ratio of 1:33 (60t/18t)²x(42t/14t) from the crankset to the motor : 115x33 = 3795 rpm at the motor
If I consider 15% of losses, theorical motor rpm are : 3795+15% = 4364 rpm
If I consider my Lipo battery at 44v (12s) : 4364/44 = 99kv

I have to ask a near of 99kv winded motor ? it could be a 11 turns ? do you agree with that ?

Turns - Kv
1 - 1060
2 - 530
3 - 353
4 - 265
5 - 212
6 - 177
7 - 151
8 - 132
9 - 118
10 - 106
11 - 96
12 - 88
13 - 82
14 - 76

I realize that if I only change my 18t HTD 5M by 16t, it's ok for standard 130kv... :

115 rpm at crank with mid drive of 1:42 (60t/16t)²x(42t/14t) : 115x42 = 4850 rpm + 15% = 5580 rpm /44v = 126kv

But I dislike the idea to have an pulley under 18t, each engaged tooth around this pulley is important to pass the torque...
I prefere have a 72t/19t instead of a 60t/16t... 72t stay as standard pulley !

Thanks for your help and involvement (everybody) :wink:
Last edited by Matt_92 on Feb 27 2018 12:06pm, edited 6 times in total.
...from France, sorry for my english :oops:

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Re: Specs Performance for 80-100 motor ?

Post by ScooterMan101 » Feb 27 2018 10:41am

Matt_92

Professional Bike Racers ride with a crankset Cadence RPM of 80 or more, they have to keep the Latic Acid from building up in their legs, and when going up hills they need to have 80 or more RPM Cadence to keep their speed up.
However
How long can you do that ? and/or is it comfortable to ride at those Crank RPM's for your legs and Hips ?

With a motor that helps you legs , by quite a large amount , 65-70 RPM is what I find is more reasonable on the body.
Even
On my non motorized bicycle an average cadence of just under 70 rpm is about perfect .
My first conversion ...

https://endless-sphere.com/forums/viewt ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

ThierryGTLTS   100 mW

100 mW
Posts: 45
Joined: Jan 10 2017 8:10am

Re: Specs Performance for 80-100 motor ?

Post by ThierryGTLTS » Feb 27 2018 10:45am

Ecyclist wrote:
Feb 21 2018 6:57pm
My reducer is already strong enough for 80mm motor, but I'm planning on a couple changes to make it better. At this point the ratio is 19:1. I machined it all excluding bearings and pins. I built other one that is 16:1.
You can visit my thread for details.

Yes, my reducer is based on the same principle, but is much better.
My reducer at no load is using about 100 W of power.
Tangent is using $700 Astro Flight ,very efficient motor, and is using at no load about 350 W.
This is a clear sign that something is wrong with Tangent. Can you guess what?

Obviously, you have technical skills and you should have no problems with building high quality and compact belt reducer.
The most important part for you will be to make it structurally rigid and running true.
I reworked GNG belt drive kit and have it still running strong on my wife's e-bike.
I'm looking forward to seeing your build developing.
Good luck.
Very interesting Ecyclist.

I plan to have the lowest possible losses for my project.

Rewound Maxon EC 90 flat + 12:1 Neugart reducer + 36/17 chain reducer draw only 600mA at 24V or about 15W with no load.

I wanna use the motor only to help in high slopes.

That will allow me to bring safe low weight battery packs.

Motor + reducers + ESC + Battery Weight = about 2.5kg.

Thierry

Matt_92   100 mW

100 mW
Posts: 39
Joined: Feb 09 2018 9:59am

Re: Specs Performance for 80-100 motor ?

Post by Matt_92 » Feb 27 2018 11:12am

ScooterMan101 wrote:
Feb 27 2018 10:41am
Matt_92

Professional Bike Racers ride with a crankset Cadence RPM of 80 or more, they have to keep the Latic Acid from building up in their legs, and when going up hills they need to have 80 or more RPM Cadence to keep their speed up.
However
How long can you do that ? and/or is it comfortable to ride at those Crank RPM's for your legs and Hips ?

With a motor that helps you legs , by quite a large amount , 65-70 RPM is what I find is more reasonable on the body.
Even
On my non motorized bicycle an average cadence of just under 70 rpm is about perfect .
ok for 70 rpm, but how fast ? 50km/h ?

I understand well your point of view, but I consider that the ratio 42/11, with 26" wheels, at 50km/h, is not something "difficult". I use to do it without motor when I can do it. But for sure, I consider 50km/h as the max speed, and it will be certainly without pedaling...

But if I have to consider the 70 rpm at crank at 50km/h (as you propose), I have to put the last chainring stage ratio at 11T/68T (instead of stock 11T/42T) and have to reduce after to the motor at 1:60... !! :shock: :shock: :shock:
...from France, sorry for my english :oops:

ScooterMan101   1 MW

1 MW
Posts: 1626
Joined: Oct 06 2012 4:45pm
Location: South of San Jose, California.

Re: Specs Performance for 80-100 motor ?

Post by ScooterMan101 » Feb 27 2018 2:30pm

Matt,

My post is meant to have you think about having to always peddle with your legs at a cadence of 115 rpm. ( a few people might be comfortable spinning their legs that fast , but not me , 65-85 rpm cadence is my comfort zone )
If
You are not going to be peddling when going 50 kph, then that changes the design and the math for the design .

When it comes to figuring out reduction ratio's I am sure you all are better at the math than me.
Otherwise I would be designing and experimenting and building one of these RC motor drives myself.
That and the fact I do not have a shop / tools/ machines to make my own . So I have to ask those of you who are designing these drives to think about as much of the operating parameters as possible before paying for Machine Costs.
And hopefully cut down on those costs as much as possible .

What cadence are you comfortable at for long times ? and at what speed that you are designing your reduction to be running at most of the time ? if at 50 kph you are not going to be peddling .
My first conversion ...

https://endless-sphere.com/forums/viewt ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

User avatar
DanGT86   10 kW

10 kW
Posts: 599
Joined: Sep 06 2012 9:18pm
Location: Saint Louis MO

Re: Specs Performance for 80-100 motor ?

Post by DanGT86 » Feb 28 2018 12:05am

Matt_92
Here is a great calculator to figure out speeds and drive ratios.

http://www.recumbents.com/wisil/e-bent/ ... ulator.asp

The 15% loss i mentioned earlier is just an estimate for the difference between the unloaded and loaded speed of a motor. A motor rated at 130kv will actually only give you around 105-110kv under moderate to high load. It helps to build in a little extra speed so you arent dissapointed. You can gear it down later if you want it slower or more torque.

I personally would try to avoid using the 11 tooth rear sprocket on a bike gearset. The lower tooth count gears wear out sooner than the higher ones. Its just like how you want to avoid low tooth count belt pulleys on the other end.

The higer the power gets compared to human legs the harder it gets to design a system that will survive human cadence. Bike chain and gears just arent designed for 10x human power but if you spin them at 10x the speed you can get away with it. Torque and Current break everything.

If you want to run 6kw and pedal along at 80 rpm at the cranks at all speeds then you are going to wear out normal bike gears really fast. That is unless you can really avoid using high power when on the 11 tooth rear gear. The chain line is usually not straight when on the 11 tooth so blasting it with 6kw is not going to end well.

Now if you want to run 30-45 tooth rear cassette and allow a small front chainring (3O-34 tooth) to spin 200rpm then you will have a much more durable setup. You just wont be able to pedal along with it at most speeds and feel resistance.

If you are building a 750-1000 watt system then normal cadence 60-90rpm and the 11 tooth rear sprocket will be ok at 50km/hr.

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