Help me choose a motor / battery set up :)

[jetzki]

This is the bike I want to convert, I know it's not ideal but I would prefer not to have to buy another bike and I have my heart set on using this one. It was my first proper bike, I now have other nicer bikes than it but I still want to use the frame for something.



I know someone will come and tell me to buy an old used mountain bike to do the conversion on, but sadly I'm not interested in them.

Don't worry I will not be riding the bike fixed gear when electric

I will add a rear brake to the bike, possibly even front and rear hydraulic disc brakes, this fork has disc brake mount on it already and I have ordered an adapter from AliExpress for the rear to see if it will fit my frame.


I saw these builds by @electric_hakan on instagram and really liked how clean stealthy his ebikes looked.


He is using the P160 all in one motor from Keyde on both bikes.


However I decided that the P160 didn't meet my power requirements and many people here said having batteries inside the hub is bad. I started looking at Keydes other motors and saw that they all have the controller and torque sensor built into the hub, so you only need the hub, one cable and your battery. So I spent some time researching this type of set up and could only find Keyde and Geeko who make stuff like this.

Rear Motor

Rear Motor

keyde.com

EBike Conversion Kit - Electric Bicycle Kit -100g.tech

Your ideal one-stop solution for eBike kits - meet Geeko ebike conversion kit.

www.100g.tech

After talking to the Keyde Alibaba sales rep, it turns out including delivery a motor, bottle battery and cable with delivery will cost $700usd / £550 gbp shipped to me here in the UK. I could get a whole brand new ready built ebike for that price locally. Geeko is even more expensive.

So now I am considering the traditional rear hub motor, controller, battery and cadence sensor route. If I can fit everything apart from the motor and the sensor inside a bag like this it would be perfect. If the hub motor isn't huge the bike could still look fairly normal.


What are my requirements from motor / battery?
I want to make this bike electric because I make youtube videos following other cyclists, many who are very fast, too fast for me to keep up with. I'm already fairly fast on my bike, I try to stay at around 20mph when I'm riding around the city often going faster, but the guys I'm following are still too fast for me. If you have any interest in my videos you can find them here https://www.youtube.com/@jetthepanda
I think I would want the motor to be able to comfortably assist me up to around 25mph - 30mph. I am happy for it to be pedal assist, I'm not very interested in the idea of a throttle.
As for distance I don't need it to go too far, my videos are only 20mins long at the maximum. I know if I'm helping the motor by pedalling too it will increase the range a lot.

My bike rear drop outs are 120mm. I need a rear hub motor that is for single speed only.

What motor / controller / battery set up do you recommend to me? I'm in the UK and happy to order from China, Aliexpress is basically my favourite online store. Budget friendly is prefered!

 

[RunForTheHills]

You probably want a geared rear hub motor, but that is not the only option that you can install on that bike. A front hub motor kit would probably be easier to install, but they can sometimes have issues with traction on loose gravel and sand. A mid-drive motor like the BBSHD attaches to the bottom bracket and powers the bike through the chain like your pedals do. In addition to geared motors (which generally have a clutch and allow you to coast without interference from the motor), there are direct drive hub motors. These do not use internal gears and are slightly bigger and heavier than geared hub motors, but they are more reliable/durable and allow for regen braking.

You can buy the motor already laced into a wheel. However, the cheap Chinese kits that you are asking about will not have a nice rim and the spokes will be laced by machine. Or you can buy a hub motor and lace the wheel yourself into a rim of your choice.

For the battery, I would recommend spending a little more and getting it from a reputable source like Grin (ebikes.ca) or EM3EV. The Chinese batteries that you no-name cells have a much higher risk of catching fire.

If you do get a kit with a throttle, you will need to use an adapter to mount it on the drop handlebars.

 

[calab]

SX2 hub motor matched to a small Phaserunner controller and whatever battery you want.
eZee hub motor would be a great choice.

Budget friendly would be a Bafang kit, but you used to be able to buy hub motor kits without the battery on ebay for $200, the battery you can buy anywhere.

 

[jetzki]

Thanks for your advice @RunForTheHills

I will be changing the handlebars to flat bars when I go electric, as I plan to use hydro disc brakes with MTB levers. Also I won't need to to get down into the drops to go fast when I have electric, I can just sit up and relax. I had direct drive rear hub motor in mind, but now I will also take geared hub motors into consideration.

Thank you for those suggestions @calab I will look into those products.

It was actually specific motor / controller / battery product suggestions I was looking for.

I am happy to buy my own rim / spokes and build my own wheel. I've built quite a wheelsets now.

 

[RunForTheHills]

After re-reading your original post, I think your biggest challenge if you want a rear hub motor is going to be that 120mm O.L.D. Most motors are intended for bikes with a 135mm or larger. If it is a steel frame, you may be able to spread the dropouts (cold set the frame). If it is an aluminum frame, that won't be possible. You actually might be better off with a front hub or mid-drive solution.

 

[99t4]

Yes the 120mm dropout width is going to make hubmotor selection difficult.

Happy for you that you have found Ali*.* serves your needs (especially their prices seem very enticing) and remain enthusiastic about it but many of us have encountered difficulties with quality, materials, design, and/or customer service, especially actual returnability and refundability of inferior/defective product. Caveat emptor.

You stated "Budget friendly is prefered!" For that I recommend you stay away from proprietary anything, esp. motors with built-in controllers, batteries, etc. Stay with common commodity-type components.

Your next step should be plugging your requirements into the motor simulator on ebikes.ca to find your battery/controller/motor capacities to satisfy your speed and distance requirements.

 

[jetzki]

Thanks again for your help guys.

I always knew it would be tough to get a hub that would fit in my 120mm drop outs. When speaking to Keyde they said they are able to customise their motors to be 125mm single speed, which would have been fine. I'm still considering using their motor only because of this. When looking at hubs I've been paying attention to ones that show the cassette spindle easily removed, or ones that just have single speed threading. I will try messaging the vendors to see if it's possible to get the motors I'm interested in, in 120mm.

I didn't really want to go mid drive, honestly I just don't like the look of it. I realise it would be an easy option and just slot straight into my bottom bracket. From what I've seen on my friends bike there are a lot of cables coming out of that motor. I guess the only one you really need is the one going to the battery. Maybe the screen too, otherwise you wouldn't be able to turn the bike on and off.

I've been thinking about my speed requirements and realised that it is asking a lot for low budget and small form factor. I guess if it's a weaker motor, but the pedal assist keeps assisting even when I'm pedalling the bike faster, it should still be helping me right? or will I just be "spinning out" against the power of the motor? I'm very happy to pedal and just have the motor give me an extra push, it was never my plan to completely rely on it.

I've never had an ebike before, I've rode hire ebikes that are dotted around the city, those ones cut out completely when you go past the 15mph speed limit and anything faster than that is all done by your legs, I definitely don't want my own bike to be doing that!

Regarding returns to Aliexpress. I understand that it could be a problem and the risks involved with shopping there. I guess I would ask the seller to give me video proof of the motor running before shipping so at least it's not DOA. I have actually recently had some refunds from them. One for wrong size product and other just because I didn't like the product, they were low value orders though.

 

[glennb]

120mm spacing is easy enough. Have you looked at Aikema 100H rear motors?

Consider a 328rpm version, with controller and battery in small saddle bag. Bottle batteries can also be neat. There’s Kunteng controllers that sit inside the bottle battery mount. You’re not fooling anyone that it’s sctually a bidon, but it’s a quick easy install.

 

[E-HP]

I agree that a front hub would work well and create fewer complications. Chalo gave you some solid advice in your other thread.

 

[jetzki]

Keyde can customise the motor housings to only have the threads for a single speed freewheel so that it will fit in 120mm drop outs. I've spoken to their sales rep and they've told me that I can use my my own battery with their motor. All their motors can be made to fit 120mm but the P110 was the one I was looking at.


A lot of rear hub motors with 135mm spacing I've seen, look like they have the thread to mount the freewheel already there, there's just the circled part in blue that makes the hub wider to fit 135mm. I wonder if those parts can just be unscrewed along the axle? If not maybe I could angle grind it flat to slot into the drop out, but then there still wouldn't be any thread for the nut to hold the hub in. If I can remove that spacer that I've circled then I can basically use any 135mm motor.

I have been messaging motor vendors to see if they can provide 120mm versions of their motors, technically it shouldn't be too hard for them. Whether they'll bother doing it for just 1 motor for little old me is another story.

By the looks of it, the above spacers should come off very easily on this motor AKM-100H 36V350W EBike Rear Driving Hub Motor [AKM-100H rear motor] - $85.50 : Zen Cart!, The Art of E-commerce going to take a look at the same brand and see if they have a 500W offering and message the factory to see if the spacers do come off easily.

 

[Chalo]

Trust me you don't want an all-in-one hub, they're crippled when new and almost irretrievable once they get tired. Putting the battery and controller in the hub is kind of like putting a gasoline generator, fuel tank, and AC inverter in your refrigerator to run it. It's self-defeating.

It's a better idea, still a little problematic but very tidy, to use a battery case that has the controller in it. Topbikekit has loads of different variations on that theme.

 

[jetzki]

I am looking into the AKM-100H motor https://www.aliexpress.com/i/32970198492.html
Just waiting to hear back from the store for them to confirm that those spacers can be removed for the hub to fit 120mm. If they can it seems like a good fit for my needs.

Regarding batteries

https://www.aliexpress.com/item/4001162408097.html

Anyone got a link to a store that makes batteries like this but with good bluetooth bms and confirmed brand name cells like Panasonic, Sony, LG, Samsung and etc.

 

[RunForTheHills]

I have front hub motors on my two Bromptons and it works totally fine in almost all situations and I think it work for your use case. You will be on pavement most of the time and won't have traction issues. You can get the clean look you want without having to deal with the 120mm rear O.L.D. and have a lot more motors to choose from. I know you want PAS and not a throttle, but the cabling will be even cleaner if you just go with a throttle and mount the battery and controller in a handlebar bag as Chalo suggested. Since you will be pedaling along with the motor, you will not need as much motor and battery as you would if you weren't contributing. The Grin motor simulator is a good place to virtually test different motors and you can tell it how much power you will contribute.

Motor Simulator - Tools



As for the battery, I would bite the bullet and spend a little more to get it from a reputable source like ebikes.ca or EM3EV. In a year from now you will forget about the extra money you spent and will still have the peace of mind of having a safe battery.

 

[jetzki]

Found this photo in this thread here AKM 100 250w vs 350w, how do they compare?


The hub body and spacers look identical to the AKM 100H

So it seems like this motor should easily fit inside 120mm dropouts
@glennb do you have any experience with this?

 

[glennb]

Yeah, it’ll definitely fit, if you elongate the flat part of the axle with grinder/file.

I have saved dimensional drawings of the motor that I’ve downloaded from various places. I can post them if you like. was going to use one as a mid-drive, because the clutch can be flipped (before opening up a Bafang G311 and discovering that it’s clutch is also reversible).

There’s a thread here from some years back with someone using one 120mm single speed.

See here: Single-speed track stealth ultralight

 

[jetzki]

I'm more than happy to take a file to the axle to extend the flat 10mm part
I've been speaking to Topebike, it seems like they can provide everything for me including the battery made from brand name cells. What's a good 18650 cell to use for ebike batteries these days?
The controllers they are recommending to me are:

T06S 24V/36V-36V/48V250W 15A KT Sine Wave Brushless Controller for Ebike FT-06 36V250W Torque Simulation Square Wave Controller Brushless Controller for Ebike [T06S controller] - $24.00 : Zen Cart!, The Art of E-commerce

ebike controller,electric bike controller,Sine Wave Controller,24v,36v,48v controller,24v controller,36v controller,48v controller,Torque Simulation Square Wave Controller,controller with display,controller with meter,6 mosfets controller,9 mosfets controller,12 mosfets controller,controller for...

www.topbikekit.com

T09S 36V/48V500W 22A KT Sine Wave Controller For ebike [T09S KT 9Mosfers Controller] - $28.00 : Zen Cart!, The Art of E-commerce

Zen Cart! T09S 36V/48V500W 22A KT Sine Wave Controller For ebike [T09S KT 9Mosfers Controller] - ★★★★★ T09S 36V/48V450W-500W Torque Simulation Sine Wave Controller For ebike 1--Rate Voltage: 36V/48V Compatible 2--Maximum Current:22±1A 3--Low Voltage Protection:DC30±0.5V 4--Speed Set: 1-4.2V...

www.topbikekit.com

Are these any good? Once I've decided on the controller I'll pretty much be ready to order everything! It's all coming together.
Do I need to have a screen and control pad of some sort on my bike? Or can I set the motor up once and then unplug them? Will I be able to power the bike on from the battery?

 

[99t4]

I am going to circle back to this part of the discussion, I have not seen it adequately addressed, bear with me:

What are my requirements from motor / battery?
I want to make this bike electric because I make youtube videos following other cyclists, many who are very fast, too fast for me to keep up with. I'm already fairly fast on my bike, I try to stay at around 20mph when I'm riding around the city often going faster, but the guys I'm following are still too fast for me. If you have any interest in my videos you can find them here https://www.youtube.com/@jetthepanda
I think I would want the motor to be able to comfortably assist me up to around 25mph - 30mph. I am happy for it to be pedal assist, I'm not very interested in the idea of a throttle.
As for distance I don't need it to go too far, my videos are only 20mins long at the maximum. I know if I'm helping the motor by pedalling too it will increase the range a lot.

Have you calculated if your chosen motor will propel you to these speeds at your chosen battery voltage?

Remember to factor in the effect of aerodynamic drag (exponentially increases with speed, can become a limiting factor unless you overspec your wattage to compensate for that). So a setup where attainable max RPM that tops out at 30MPH may not reach anywhere near that real world, when it has to deal with aerodynamic drag and hills. Moreso after you make your switch from dropbars to flat bars.

Also, have you calculated the wattage requirements to maintain that speed? Over time? Will the battery be sufficient to maintain those speeds for duration of your planned 20 mins? TIP: Overspec your batter also. Your top speed will drop over the length of your ride as the battery voltage drops naturally with discharge. And most all batteries deteriorate with use and chronological aging.

You state you are a strong cyclist and will be pedaling with gusto. I do too! In my experience, pedaling a 22 MPH ebike to 30 MPH is NOT just like pedaling the 8 MPH difference. After the motor tops out, it is more like pedaling the full 30 MPH!

Take the time now to experiment with the motor simulator, it's informative, user interactive, and fun!-- forum member RunForTheHills started one for you above. Pay close attention to the wattage and Ah requirements.

Here it is again, in case you missed it:

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

 

[jetzki]

The person I was talking to over at topebike was telling me I'll easily get up to 25mph with the motor I'm looking at, but you've got me doubting him @99t4
I'm playing around with that simulator now Seems like I will definitely need a 48V battery to get close to 30mph.

 

[999zip999]

48v wakes up a motor. This is one time I would okay a small geared motor for the front. Don't get me wrong I think rear motors are their way to go.
Looking at that photo again that's a pretty special front wheel by the looks of it ?
Thank yo

 

[James340]

I installed a Bafang bbs02 in a 1990's MASI and love it.It is a 9 speed cassette & required a 14 mm off set chain ring for good chain line.

 

[glennb]

You’re getting good advice. The point about speed reducing proportional to battery voltage is important in your use case. The fast wind AKM100H is up to the task. The KT controllers are also good, except you’re going to want >52V and/or field weakening. You’re a good candidate for VESC.

And if you want to be damn sure about maintaining 30mph with a sleek setup you’re going to need an aero position. Flat bar will cost you more speed than you can afford to lose. I used to prefer a superman position setup, but am not in such a hurry these days, and the steering was always horrible, so use narrow (360mm) drop bars. They make a big difference. You’ll need to go beyond Grin’s calculator to get useful drag coefficient calculations. There’s not even a “Lycra vs baggy jeans” option with Grin.

 

[jetzki]

@glennb I'm actually planning to get 340mm drops on one of my other bikes I want to use on the velodrome!
It's not imperative for the build to maintain 30mph for a long time, if the person I'm filming can manage to get up to that speed, they won't be able to keep it up for long due to London traffic. If the bike can get past 25mph it should be fine, I'll push it the rest of the way with my legs.
I was thinking about VESC before, I know they're usually a small size and highly configurable. Seems like not that many people use them though? No idea why that is. I don't know why, but for some reason I have the idea they might be unreliable, maybe I read or watched something about them in the past.
Do you mean I would need to go 52V controller and battery? or just controller?
I don't know what field weakening means something else for me to research!

 

[amberwolf]

I was thinking about VESC before, I know they're usually a small size and highly configurable. Seems like not that many people use them though? No idea why that is. I don't know why, but for some reason I have the idea they might be unreliable, maybe I read or watched something about them in the past.

VESC is a general project VESCproject.org for an open source controller design, that anyone can build. There are various companies producing their own versions of it, for systems as small as little hobby RC aircraft and as big as cars, trucks, etc.

Each company, being there for profit, has their own ways of making it that conform to their ideas of how good it should be, etc., so each one has different quality, support, and level of matching the state of the project (or contributing back to it / making the sources available, compatibility with the rest of the project, etc).

Reliablity is also not just how well made or designed something is, it is how suited it is for your application, in all the various factors, so you can put the most reliable hardware in a situation it's not intended for and be unable to use the system as a whole as you wanted to.


FOC controllers (like VESC, Phaserunner, etc) can be smaller than a generic "brute force" controller partly because they can be tuned to work *with* the motor, etc., instead of just "pushing as hard as they can" to do a job. It doesn't mean they *are* any better at a specific job if they're not setup and tuned for it, but they could be made to be.

One reason less people use FOC controllers than the other type is that any FOC controller does have to be tuned to it's usage and motor, battery, etc. Some (like VESC) have pretty good autotune routines, but nothing is perfect, and it can take some serious time and experimentation on some of them to get the system as a whole to do the job well. Most people don't want to deal with that, or can't, so they use the stuff that doesn't require any real setup, just plugs in and goes (but isn't tunable to work "better").


Some controllers, like those for RC aircraft / etc applications, are often meant for *very* short bursts of high power, with longer periods of lesser power, and short overal runtimes (because of the small batteries in the "toys"). So they can be small with little heatsinking and/or little thermal mass. Some of them can be made to handle higher power for longer, but it's easier to start with a version meant for the application.

Do you mean I would need to go 52V controller and battery? or just controller?

Has to be both; if you have a controller capable of a certain voltage, it will still only do whatever the voltage you provide to it does.

(bad analogy, but you can have a box that holds 12 books but if you only have 10 books you are still only carrying 10 books worth of info).

I don't know what field weakening means something else for me to research!

Some threads that might be helpful

Search results for query: field weakening

endless-sphere.com

 

[jetzki]

So before I was told to look into a VESC controller, which I now am. The below components were what I was ready to purchase.
AKM-100H 48V350W Hub Motor

AKM-100H 48V350W 36Holes Front/Rear Driving Hub Motor [AKM-100H 48V350W] - $90.00 : Zen Cart!, The Art of E-commerce

Zen Cart! AKM-100H 48V350W 36Holes Front/Rear Driving Hub Motor [AKM-100H 48V350W] - ★★★★★ AKM-100H 48V350W 36Holes Front/Rear Driving Hub Motor Specification: 1. Voltage: 48V 2. Brake type: V-brake, rim brake and disc brake are compatible 3. Connector: 9Pins Motor Cable Plug 4. A speed sensor...

www.topbikekit.com

T09S 36V/48V500W 22A KT Sine Wave Controller

T09S 36V/48V500W 22A KT Sine Wave Controller For ebike [T09S KT 9Mosfers Controller] - $28.00 : Zen Cart!, The Art of E-commerce

Zen Cart! T09S 36V/48V500W 22A KT Sine Wave Controller For ebike [T09S KT 9Mosfers Controller] - ★★★★★ T09S 36V/48V450W-500W Torque Simulation Sine Wave Controller For ebike 1--Rate Voltage: 36V/48V Compatible 2--Maximum Current:22±1A 3--Low Voltage Protection:DC30±0.5V 4--Speed Set: 1-4.2V...

www.topbikekit.com

48V15AH Samsung INR21700-50E Li-ion Battery 13S3P

48V15AH Samsung INR21700-50E Li-ion Battery Small size and large capacity [48V15AH Samsung 21700] - $249.00 : Zen Cart!, The Art of E-commerce

Zen Cart! 48V15AH Samsung INR21700-50E Li-ion Battery Small size and large capacity [48V15AH Samsung 21700] - ★★★★★ SPECIFICATION: 48V15AH Samsung INR21700-50E Li-ion Battery Small size and large capacity 1-Capacity:48V15AH SamsungINR27100-50E 2-Cells in series:13S3P, total cells:39pcs...

www.topbikekit.com

A display

KT LCD8S Color Matrix Display Meter 24V/36V/48V with Julet Waterproof Plug [KT LCD8S Julet Waterproof Plug] - $49.00 : Zen Cart!, The Art of E-commerce

Zen Cart! KT LCD8S Color Matrix Display Meter 24V/36V/48V with Julet Waterproof Plug [KT LCD8S Julet Waterproof Plug] - ★★★★★ SPECIFICATION: 1--The display can show the speed, single range and accumulated range, time, PAS level, power, temp, battery voltage and capacity. 2--You can set speed...

www.topbikekit.com

and a PAS sensor

Am I missing anything? are brake cut off wires to the controller necessary? I will be running front and rear hydro disc brakes, I'd rather not have the extra cables if I don't have to.

Thanks for the vesc explanation @amberwolf
While I'm looking into VESC's do you guys have any particular models you recommend? I really have no idea about them, but I like how customisable they seem to be. From what I understand the display I've linked above won't work with a VESC

Topebike and AKM have confirmed with me that the motor with the spacers removed is 122mm OLD which is fine for my needs.

I would like to order asap, just need to figure out exactly what I want first

 

[amberwolf]

are brake cut off wires to the controller necessary? I will be running front and rear hydro disc brakes, I'd rather not have the extra cables if I don't have to.

All they do is tell the controller to stop powering the motor. If you have PAS only, then stop pedaling and it does that, or if you have a throttle let it drop back to zero and it does that.

If you were using regen braking, then the ebrake signal usually tells it to engage this, but AFAIK the AKM100 is a freewheeling geared motor, so it wouldn't do regen anyway.

From what I understand the display I've linked above won't work with a VESC

I don't know specificaly which ones will, but the VESCProject site should have a page that lists which, if any, do.

There is at least one project here on this forum (and probably others out there) for a program to run on a tablet/phone/etc to use as a VESC dashboard. I don't know how far along they are; if theyr'e in a an end-user state yet.

Search results for query: VESC display

endless-sphere.com

there's probably others.