2022? Lightweight Front or Rear Hub Motor for Road Bike to eBike Conversion

[Chendy]

Hello

I've got a decent road bike, thinking of converting it to an eBike with a rear hub motor.
If I have a standard rear-wheel spare, I can use an acoustic or eBike by simply swapping the rear wheel, etc.

I don't need much power assistance, I would say 200W - 250W is enough.
My priority is low weight.

I've found the AIKEMA 85SXC 2kg motor, which claims to work in a 700cc wheel.
Any thoughts on this or other recommendations?

I'm in the UK

Thanks : )

 

[Chalo]

Why rear? Front hub motor is much easier to convert and doesn't leave you with a weak and crappy rear wheel.

If you intend to switch back and forth between motor and no motor (which is a bad idea), front motor is much easier for that too.

 

[Chendy]

OK sure, if you have lightweight recommendations for that.

I just thought it might ride weird, with power coming from the front. But I have never tried.

 

[LewTwo]

Well if you really want light weight then I believe that at 1.2 kg (2.64 pounds) the Q75 may be the lightest weight hub available. Be forewarned that it is a 28 spoke hub.
https://bmsbattery.com/20-motor
https://bmsbattery.com/ebike/581-16212-q75-36v200w-front-v-brake-e-bike-motor-wheel-ebike-kit.html#/213-rpm-201

Another popular contender at 2.3 kg (5.06 pounds) is the Bafang G311:
https://ebikes.ca/product-info/grin-kits/bafang-g310-g311.html
https://ebikes.ca/shop/electric-bicycle-parts/motors.html

 

[Chendy]

Excellent, please keep them coming.
To clarify, I've searched forums for different options, but not sure what the score is for 2022. Lots of older posts

Also, doesn't have to be the literal lightest possible. Happy for some sub 2.5kg, if the added performance justifies the extra weight : )

 

[999zip999]

A motor on the front fork is okay if you have a steel or chromoly steel pork I don't particularly like them on aluminum front forks
A motors okay in the rear in aluminum frame with a torque arm or two to support it.
Yes a small geared motor for the rear at 48 volts.
Is it a 7-speed 8-speed or 10 speed rear end ?
As you may need a motor for a cassette or you may use the more common motor that takes a freewheel
What battery are you going to use and where you going to put your controller make sure if you have limited room to make a cardboard box the size of the battery that you want to use to see how it fits and or controllerb before you buy. Make all the pieces fit in your mind or on your frame or with cardboard boxes.

 

[sleepy_tired]

Unless you want a lot of power there isn't anything wrong with a front hub motor. There isn't any real benefit going for a rear motor until you get up past 750-1kw or so. Over 350 watts output you'll probably want a torque arm if one isn't built into the motor. Just to prevent possible damage.

I have a front 1kw hub motor and while it may spin when starting from a stop at the bottom of a hill it has never been a issue in practice.

If I was to do it again I would buy this:

https://ebikes.ca/product-info/grin-products/all-axle-hub-motor.html

It is not "lightweight", but for a direct drive it is. At 4kg it is lighter then most mid-drives.

Otherwise a Bafang g311 is about the smallest I would like to go:

https://ebikes.ca/shop/electric-bicycle-kits/bafang-g311/g311-front-minimal-rtr-kit.html

If you want something very simple to install:

https://hilltopperbikes.com/product-category/electric-bike-kits/

I would go with the horizon kit at least.

 

[docw009]

Have you considered a mid drive motor? The TSDZ2 seems to be popular in UK bike forums. There is a new version, TSDZ2B, which should address reliability issues with the original versions.

I have one of the older models, but never installed it til this Fall. I paid $355 USD for it, about $75-100USD more than what a hub motor,rim,spokes and electronics usually costs me. My other mid drive is a BBS02, and what I like about them is no electronic box locate/conceal on the bike frame. Also no changes in the wheels.

I put the TSDZ2 on an old 27" road bike. It only draws 13 amps peak, about the same as most 250W hub motor controllers, and i can run it on a small battery. On the other hand, it has the power of a 250W hub motor. Nonetheless, it maintains the character and looks of my road bike, and I guess I'm just an old poser. It's also a torque sensing kit, rather than a cadence sensor. That is also different to me.

 

[Ernie]

TSDZ2 are quite heavy and need a fair bit of maintenance and spare parts compared to a hub motor, I have one, and that's why I was looking at this thread to see if there are better less maintenance options. I basically use the eBike to do grocery shopping, so I figure a 250w front hub motor maybe all I need.

 

[uhmwpolyethylene]

Well if you really want light weight then I believe that at 1.2 kg (2.64 pounds) the Q75 may be the lightest weight hub available. Be forewarned that it is a 28 spoke hub.

Motor

bmsbattery.com

Q75 36V200W Front V-Brake E-Bike Motor Wheel RPM 201

Q75 36V 200W Front Driving V-Brake E-Bike Motor in an Aluminum Alloy Double Wall Rim. Only S06P and LSW-675 controller fits for this motor.

bmsbattery.com

Another popular contender at 2.3 kg (5.06 pounds) is the Bafang G311:

G310-G311 - Grin Kits - Product Info

The small G311 front / G310 rear motors from Bafang are well suited for those wanting light and discrete conversion for moderate assist levels. A high reduction helical gear set allows these tiny motors to deliver a surprising punch without any of the buzzing noise commonly associated with...

ebikes.ca

Hub Motors - Ebike Parts - Shop

We carry a very wide assortment of front and rear hub motors for just about every need. From the tiny G311's to the mighty RH212. All our motors are unlaced and can be hand-built into a rim of your choosing. Most motors are available in at least two different winding speeds as well.

ebikes.ca

This is cool, is it possible to disassemble it and put it in a non crappy wheel? Is the weight of just the unit 1.2lg? And this is front wheel caliper only?

 

[amberwolf]

Depends on what you mean by "non crappy wheel", and which motor you're referring to (presumably Q75).

 

[Chalo]

This is cool, is it possible to disassemble it and put it in a non crappy wheel?

Cheaper to get just the hub. Then you can use good spokes, good rim.

Q75 28 Spoke Holes 36V Front-driving Hub Motor RPM 201

Q75 28 Spoke Holes Front-driving High Speed E-Bike Hub Motor

bmsbattery.com

Is the weight of just the unit 1.2lg?

Yes, I think so.

And this is front wheel caliper only?

It doesn't look disc compatible, but some places say it is (though maybe they're just recycling text from other listings?)

That and other Q-whatever motors are made by Aikema. Topbikekit sells them as AKM-whatevers.

ebike hub motor,front motor,24V/36V/48V motor,200-350W motor,500w motor for electric motor

ebike hub motor,front motor,rear motor,24V motor,36vmotor,48v motor,200w motor,250w motor,350w motor,500w motor for electric motor,high speed motor,low speed motor,high torque motor,fast motor

www.topbikekit.com

 

[uhmwpolyethylene]

Cheaper to get just the hub. Then you can use good spokes, good rim.

Q75 28 Spoke Holes 36V Front-driving Hub Motor RPM 201

Q75 28 Spoke Holes Front-driving High Speed E-Bike Hub Motor

bmsbattery.com

Yes, I think so.



It doesn't look disc compatible, but some places say it is (though maybe they're just recycling text from other listings?)

That and other Q-whatever motors are made by Aikema. Topbikekit sells them as AKM-whatevers.

ebike hub motor,front motor,24V/36V/48V motor,200-350W motor,500w motor for electric motor

ebike hub motor,front motor,rear motor,24V motor,36vmotor,48v motor,200w motor,250w motor,350w motor,500w motor for electric motor,high speed motor,low speed motor,high torque motor,fast motor

www.topbikekit.com

That's pretty sweet, I mean it's even lighter than the Mahle x20 but not proprietary and dirt cheap, and more compatibility with a super high end road frames than a mid drive.i wonder if you could do some kind of bottom bracket torque sensor with this like the Mahle, or replace some of the body with lighter material like magnesium etc. It really has potential at a very low price. 200w is practically what the specialized Creo charges 6-8 grand for , and their frame for their internal motor and battery is crazy heavy. I'm following the bikee lightest also, 6 lb mounted? Maybe 8 or 9 with controller etc idk but it doesn't seem to be going anywhere... my only other reliable option seems to be specialized Creo or the 13+3 lb bbshd

 

[uhmwpolyethylene]

Cheaper to get just the hub. Then you can use good spokes, good rim.

Q75 28 Spoke Holes 36V Front-driving Hub Motor RPM 201

Q75 28 Spoke Holes Front-driving High Speed E-Bike Hub Motor

bmsbattery.com

Yes, I think so.



It doesn't look disc compatible, but some places say it is (though maybe they're just recycling text from other listings?)

That and other Q-whatever motors are made by Aikema. Topbikekit sells them as AKM-whatevers.

ebike hub motor,front motor,24V/36V/48V motor,200-350W motor,500w motor for electric motor

ebike hub motor,front motor,rear motor,24V motor,36vmotor,48v motor,200w motor,250w motor,350w motor,500w motor for electric motor,high speed motor,low speed motor,high torque motor,fast motor

www.topbikekit.com

Oh nice a 48v one too



Some discussion on q75 Q75 Hub motor

I could see this being nice on a high end road bike if you don't mind trashing one of your expensive hubs for this piece of junk, or on a brompton / Ti Brompton with a little 2-4 lb battery

Or even... Using a hub motor as a mid drive?

 

[999zip999]

Very good a lot of options here I would like to see a picture of your road bike and what speed it is.
What type of writing will you be doing and how steep will the hills be. This will help determine what motor kit to get in a picture or model number of your bike well let us know what battery and where would be easiest for you to put it.

 

[uhmwpolyethylene]

The q75 looks quite good, but I wonder what the absolute highest quality hub motor with best power/weight ratio is and where you start hitting diminishing returns, a 750w nominal 1200w peak hub that fits in a Brompton fold would help a lot, the e Brompton is heavy steel and the 350w stock front hub sucks, maybe rear hub is better, and the 6 lbs battery doesn't last long and mounts high on the front.

 

[motomech]

The Q75 is sensorless and that wouldn't be good on a single motored bike. And I'm not even sure if it will take a disc.
When I was knee deep in mini motors, I looked at everything avail. at the time and kept comming back to the Q100 (Love/hate relationship).
The problem with it, is the high-speed version (328 rpm @ 36V) is too high a range for wheels 24" and over, which leaves the mid-range 260. The best Q100 is the 260H w/ free wheel fitment. The cassette version has a narrower stator to fit the wide cassette and makes less power than the already less-than-powerful Q100.
280 or 290 would be a better speed range for road bikes w/ 27 to 29" wheels, but it, of course, doesn't exist.
All will benifit from over 50 V packs, especially bike using 26 or 27" wheels to get some top speed.
There are hub motors that are higher quality than the Cute (it isn't that hard), but they start at 2.4 Kg, vs. the Q100's 2.0 Kg.

 

[1boris]

The q75 looks quite good, but I wonder what the absolute highest quality hub motor with best power/weight ratio is and where you start hitting diminishing returns, a 750w nominal 1200w peak hub that fits in a Brompton fold would help a lot, the e Brompton is heavy steel and the 350w stock front hub sucks, maybe rear hub is better, and the 6 lbs battery doesn't last long and mounts high on the front.

Q128H has nominal power 800w

AKM-128HCST 36V/48V800W Rear Driving Hub Motor Cassette motor For ebike [AKM 128H CST 36V/48V 800W motor] - $147.25 : Zen Cart!, The Art of E-commerce

Zen Cart! AKM-128HCST 36V/48V800W Rear Driving Hub Motor Cassette motor For ebike [AKM 128H CST 36V/48V 800W motor] - ★★★★★ AKM-128HCST 36V/48V 800W Rear Driving Hub Motor Cassette motor For ebike Specification: 1. Voltage: 36V800W or 48V800W 2. Brake type: V-brake, rim brake and disc brake...

www.topbikekit.com

Q128H 36V800W Rear Driving EBike Hub Motor RPM 201 Voltage 48V

Q128H 36V800W Rear Driving V-brake, rim-brake, Disc-Brake compatible E-Bike Hub Motor. Waterproof hall sensor connector.

bmsbattery.com

 

[uhmwpolyethylene]

Q128H has nominal power 800w

AKM-128HCST 36V/48V800W Rear Driving Hub Motor Cassette motor For ebike [AKM 128H CST 36V/48V 800W motor] - $147.25 : Zen Cart!, The Art of E-commerce

Zen Cart! AKM-128HCST 36V/48V800W Rear Driving Hub Motor Cassette motor For ebike [AKM 128H CST 36V/48V 800W motor] - ★★★★★ AKM-128HCST 36V/48V 800W Rear Driving Hub Motor Cassette motor For ebike Specification: 1. Voltage: 36V800W or 48V800W 2. Brake type: V-brake, rim brake and disc brake...

www.topbikekit.com

Q128H 36V800W Rear Driving EBike Hub Motor RPM 201 Voltage 48V

Q128H 36V800W Rear Driving V-brake, rim-brake, Disc-Brake compatible E-Bike Hub Motor. Waterproof hall sensor connector.

bmsbattery.com

Interesting. I wonder if you could also take the q75, drill holes and put waterproofing spray/ statorade in it, use it as a mid drive mount on a Road bike/bromp I also saw AKM makes brompton wheel motors, AKM-74SX, 1.4kg but the crystallite saw20 3.2kg /7 lb seems to be the best one, grintech who sells a saw20 wheel and controller says their older 1.8kg / 3.9 lb 250w motor wasnt so good. With your wheels so close to the ground though, maybe drilling holes isnt ideal. (Also I saw a guy talking about adding fans into a hub motor. Can you do that???)

All will benifit from over 50 V packs, especially bike using 26 or 27" wheels to get some top speed.
There are hub motors that are higher quality than the Cute (it isn't that hard), but they start at 2.4 Kg, vs. the Q100's 2.0 Kg.

What can they handle? With what controllers, or custom controllers? Sorry im new to this. 52v? 72v? even more? Put in statorade like this? He's pumping like 800-900w into a SAW20 250w motor and it seems to be working well with the statorade

I wonder how much weight would be added to mount a q75 or q100 as a mid drive though and how that would compete with the Bikee lightest at 6lb mounted (if it works), or a drilled q75

 

[uhmwpolyethylene]

The Q75 is sensorless and that wouldn't be good on a single motored bike. And I'm not even sure if it will take a disc.

The more I thought about it, if you could take the time to replace the Q75 case perhaps with magnesium or something it might be better than Mahle for an ultralight front hub motor on an expensive road bike and won't interrupt your precious ultegra/dura ace drive, although like you said maybe no disc

 

[amberwolf]

if you could take the time to replace the Q75 case perhaps with magnesium or something

How much money do you have to buy a big enough billet of the chosen metal, and pay someone to draw up the dimensions/etc to re-create the casing, and pay someone to machine the billet from those?

What is the weight difference between Magnesium and Aluminum? A quick search says only 33% lighter, so it still weighs 2/3 of what the motor's alreayd made with. And that is only a small part of the motor weight--most of it will be the actual motor itself, copper and steel and magnets, and the axle and the clutch and gears, etc.

You might want to do some research for the various ideas you come up with to see if they are practical.



If you're looking for the lightest possible bike, you leave off the motor and batteries and just use a pedal bike.

If you need a light motor, then the *first* thing you have to do is not find a light motor, it is to define the job you need the bike to do for you, under the specific riding style and conditions and weather you have, and then use calculators / simulators like those at ebikes.ca to see how much power you actually need to do this.

Then you can use that to find out how big a motor and controller and battery you actually need to do this job.

*Then* you can go looking for motors, controllers, and batteries that can do that.


Just looking for the lightest motor won't help you, unless your entire goal is to just have the lightest motor possible on a bike, whether it can actually be useful or not. ::bad joke mode on:: In that case, you can go with tiny sugar-cube-sized toy motors and 9V batteries, no controller needed. It won't do anything useful to drive the bike, but it's really light. ::bad joke mode off::

 

[uhmwpolyethylene]

Nah it's true, and yeah I see what you're saying. but even 200w is doubling /tripling the power the average person puts out, and you're avoiding messing with your drive chain or having a heavy bottom bracket and downtube battery like the specialized Creo. I don't own a lightweight road bike but if I did, I could definitely see using something like the q75. (Laced to carbon rims of course .. but does it even support disc) people shell out 14+grand after tax for the s works Creo and it still weighs like 31lb. For that if you really wanna go nuts get a ax lightness 10 lb bike, throw on the q75 and a 2-4 lb battery, heck the Creo only has a 4 lb battery iirc. And you're still more future proof. Would I do it? Maybe not. But I see what you're saying and I realize now about the case being alu.

 

[calab]

but even 200w is doubling the power the average person puts out

I doubt its 200w for the average person, it'd be much less.

 

[uhmwpolyethylene]

The Mahle x20 has a torque sensor at the crank but I'm unsure if that requires a proprietary frame or what. and of course you're probably saddled with propriety batteries. It hardly looks "aero" either. On a bike this expensive you'd think it would mess up your fancy dura ace / ultegra / grx800 anyway. I wonder how a fancy groupset goes with the Mahle.
Says internal battery so probably propriety ofc, and that means a heavier downtube

Bikes with the MAHLE X20 drive system include the BMC Roadmachine AMP TWO, Orbea Gain, and SCOTT Addict eRIDE.

Sounds quite lame really, just for people willing to toss a 13,000$ bike

The Insider's Guide to MAHLE X20: Updates, How-Tos, and Our Favorite eBikes

We’ve had great success with the MAHLE X35 drive unit. Not only is it one of the most common electric bike systems in lightweight road and gravel electric bikes, but it was so low-profile in it's look that the only way one might realize an X35 bike was electric was by lifting it up. The new...

contenderbicycles.com

This is done through the inclusion of a torque sensor, a first for MAHLE. This sensor - effectively built into the bottom bracket of the bike - measures pedaling force exerted by the rider through the cranks to more precisely give out power as needed. While most mid-drive electric assist units have one built in, a torque sensor adds complication and weight, so the X35 calculates how much it offers assistance by comparing wheel speed to how fast the cassette is spinning. Adding a torque sensor takes some of the guesswork out.


On the whole I don't really wanna support the greed of companies like specialized charging 1000+ tax for a replacement 4 lb battery, but the Creo 1 is a fairly decent production.... The Creo 2 gravel setup is goofy though. And as always the euro market 250w continuous or 500w peak for the boat anchor MTB specialized ebike is kinda wack

 

[uhmwpolyethylene]

But if you WERE to go a company in China or wherever and be like , I wanna do the Swytch Kit but as an aero front hub mega ultralight disc brake compatibility motor to be laced into people's existing bazillion dollar Aethos climbing bike carbon/berd spoke/whatever wheelset that they've already invested way way way too much money into for an amateur rider..... You could probably convince people