Small hub motor

guyrandom1

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Joined
Nov 2, 2019
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3
Location
Atlanta, Georgia
I have been interested in building a small hub motor ebike as a road bike conversion. I have been an off and on bike rider, so have a road bike that I am looking to augment with a small motor to give it an occasional boost (throttle only), but intend to ride it 99% of the time on pedal only. As such, I am fine with lower power (250W or so), and am thinking front hub. For simpler build. I am wanting as light as possible to keep the experience as close to traditional road bike as possible. Stealth is nice, but secondary really to weight and maintaining a traditional experience

After looking at my options, the one I had settled on was the Bafang G370, but am having trouble locating a vendor. There are a handful of options on Alibaba but all require larger quantities. Anyone know of a vendor for these? Any other recommendations?
 
I don't have the background to help with the motor. But I will suggest that a rear motor will look more traditional (tucks in behind the cassette and disc nicely) and probably give a more traditional riding experience (power applied to the rear wheel) and it really isn't a lot more complicated. Also, some info in your bio on your general location might help others give you assistance with where to buy.
 
If all you want is a nominal 250W of assist, then there are smaller and lighter motors to choose from. Q75 comes to mind, with a claimed weight of only 1.2kg.

https://bmsbattery.com/motor/593-16233-q75-36v-front-driving-hub-motor-ebike-kit.html
 
I am looking to augment with a small motor to give it an occasional boost (throttle only), but intend to ride it 99% of the time on pedal only.
If this is truely your intent, then forget the electric system and put your money in a better road bike.
The idea of pedaling around w/ a motor installed and carrying a battery is not really a valid concept. Even though a non-energized lightweight, low-drag motor shouldn't add much effort, it adds more than one would think.
The way the vast majority of riders ride an assist bike is to set the power low and "pedal on top of it".
Probably the most popular "value" motor would be the Q100C (originaly called the Cute) available from BMS Battery and others.
Another common noobie misconception is PAS (Pedal Assist System) is not wanted. It is most deffinately the way to go.
Since the "feel" of the pedal/motor interface seems important to you, you would want to use a sine wave "torque imitation" controller.
Tons of info here on the assist systems for you to study.
Probably the most important thing is matching the motor speed range to the Battery Voltage and the donorbike whl. size.
I would recommend you do NOT use Alibaba, especially these days.
 
Maybe a brick of LiPo from Hobbyking and a 200W motor with a 24V ([+/-]6S) controller if the speed is sufficient then that may suffice or 36V (10S), but you really need a nice road bike rather then considering an ebike for 99% pedal. Your ideal setup would be pedal assist all the time, it will get you further distance faster.
 
A few of the guys who built lightweight road bikes carry the battery in a backpack with a quick release electrical connection of some kind. They seem to think it is a valid concept. I guess that all depends on the person.

In the end, its all up to you to decide. Here are a few threads for lightwave low power builds that might help you get the insight you need. There are others.

https://endless-sphere.com/forums/viewtopic.php?f=6&t=91309
https://endless-sphere.com/forums/viewtopic.php?t=93180
https://endless-sphere.com/forums/viewtopic.php?t=49691
https://endless-sphere.com/forums/viewtopic.php?t=89136
https://endless-sphere.com/forums/viewtopic.php?t=98059
 
Possible solutions
Friction drives that rub the tread off rear wheel would be a light weight solution, until there is rain or mud or a hill.

Maybe a motor to a belt drive on the side of the wheel attached to the spokes.

Unite Motors (eg. MY1010) - quick web search - https://www.monsterscooterparts.com/24v30mowisp.html

Small motors attached like a rear derailleur??????????? iZip - https://www.pedelecs.co.uk/forum/threads/izip-with-cb26-battery.24429/

200-250W hub motor - 8Fun Bafang - You really gotta look at what the people in the UK do for low power stuff. Which brings us back to the Pedelec forums - https://www.pedelecs.co.uk/forum/threads/difference-between-250w-vs-350w-bafang-8fun-hub-motor.21232/
*Also look at BMS Battery

250W enough article
https://www.electricbike.com/250-watt-hub-motor/
 
A few of the guys who built lightweight road bikes carry the battery in a backpack with a quick release electrical connection of some kind. They seem to think it is a valid concept. I guess that all depends on the person.
My reply, lacking much O.P. rider info, is geared towards the majority that might be reading.
Serious cyclists (Lycra types) are super human and break all the rules, but I suspect most here (We could do a poll) ride to commute or ride for recreation (exercise).
Heck, serious cyclists can do high 20's MPH on a mini-motor but I wouldn't make a blanket recommendation for people to try that.
 
Besides, I think carrying a pack, no matter how small it is, is a little fanatical.
I really think for folks that are happy in the low 20's MPH range, don't have any huge hills and want a good workout with a minimum of ebike fuss, the tried and true combo of shark batt., KT sine wave controller and a mini motor can't be beat. The "Torque Imitation" feature is a bit of clever engineering.
The fly in the ointment is the non-availability of the Mini w/ a cassette mount in the mid-range speed (260 rpm @ 36 V). That forces the choice of a fairly low speed motor (201) or the super high speed 328.
The 201 can be kept in the low 20's MPH when used in 26" whl.s and bigger, especially w/ 52 V applied but the 328 in 26" whl.s and bigger creates a new set of prob.s. And every time I recommend folks don't try and run a 328 in a big whl, someone will let us know they do it, can go 27 to 29 MPH and climb hills without melting wires.
It's not for me to doubt their claims, but I can't imagine many can do that.
I guess people need to be honest about their abilities before building a lightweight assist system.
Which brings us full circle;
I guess that all depends on the person.
 
motomech said:
I guess people need to be honest about their abilities before building a lightweight assist system.
Which brings us full circle;
I guess that all depends on the person.

Exactly. All I (we) can hope to do is point people toward good information. They have to decide how applicable it is.

And I agree. I think most people don't want a lightweight low powered ebike. But for now, I'm taking the OP at face value until there is reason to think otherwise.

On a side note, I hated the torque simulated feature on my KT controller. It seemed to provide less power the harder I'd pedal. So I now just dial in the PAS value between 1 & 5 that fits my current situation.
 
A few days ago I installed a Bafang G311 front motor on my wife's Townie. This is a very small and light hub motor also called a G01. She pedals mostly but uses the motor for assist when climbing, it works very well.

https://www.ebikes.ca/product-info/geared.html

G01 series aka G311 front and G310 rear are geared hub motors with 11:1 gear reduction. Gears in this hub are helical which reduces gear whine to the point that I can't hear it. My direct drive hubmotor makes more noise. The controller is a Grin 20amp unit, the battery she has used is a 13s, 4p, 18650 GA cells, shark container, from Luna. This controller can run on either 36v or 48v, that is 10s and 13s. Weight and size are much less than my DD hubmotor.

The tiny G311 has superior acceleration from a stop and better climbing ability than my DD hub. G311 and G310 can use a disk brake rotor, which helps hide the hub. The G311 and 310 hubs have very little drag when pedaling only. Battery use is much less than with my direct drive hub. G311 is the front hub motor, G310 is the rear hub. A front hub leaves your gearing the same as before conversion. Dropout spacing is 110mm for the 310 and 138mm for the G310. Throttle can be thumb or twist grip.

Non torque sensing PAS has never performed well for me, so I did not install PAS on this conversion, minimum throttle response gives more acceleration and speed than I'd like, but it is still very controllable. My DD is easier to control at very low speeds.

I'm thinking the G01, aka G311 and G310 hubs would be an excellent choice for road bike assist. I'd choose the high rpm, glued magnets option for road bike use.

Hope this helps.

Best Wishes,

Mike S in San Antonio
 
Thank you everyone for the feedback.

I may need to test drive an ebike with pedal assist off to see if the concept is even valid, or if the drag (as motomech pointed out) is enough that I will end up wanting pedal assist just to at least cover the tax of even a lightweig non motorized motor. I did a lot of test rides but don't know if I focused on that aspect sufficiently.

I am somewhat of a very soft version of a solo lycra rider. I do long rides (recreational / exercise) on what was at one point a higher end road bike (older Trek OCLV carbon modified with MTB gearing to help with hills). But, I only do about 250-500 miles a year, and somewhat erratically. Enough that I can do 20-30 miles rides, but infrequent enough that I end up having to walk up the last part of some of the hills because of human motor overheating and giving out. I'm really looking for something to kick in when I would normally give up and walk up the hill (even with the lower MTB gearing) so would take something that gives just a few mph to assist me there. My average speed is slow for road bikes ... 10-12 avg mph for most rides, but I am fine with that.

I also do some mountain biking, and have ended up purchasing (eta end of November) a Frey Hunter to try out eMTB to give that a try. That also gives me the other end of the spectrum (and I will likely use that to run errands and possibly commute in a more assisted pattern), and I went big there (motor wise) because it will open up a lot forest service road riding that I love but have given up on because of just not being up to physically. But, I also want to still do more rec/exercise riding, and want something that will walk the line between helping me get to the top of the hill while still forcing me to do most of the effort. Plus, it looks like it would be fun to do a self build, and I cant think of an excuse to build something that is high powered like what I am purchasing off the shelf. Hence my lightweight road bike project.

Coming back, the Q* ones had looked on point, but had seemed.problematic from a quality perspective...am I dismissing them to quickly? The rollers looked...more concept than practical. I hadn't seen much personal reports on them to make me.feel comfortable with that route.

Regarding front / rear, I am fine with unnatural (at least unless I end up having to accept low level pedal assist after more test riding) because of when I am looking to engage the motor. The installation seemed fine enough, but a lot of motors end up not leaving room for my existing drive train (10 on rear), so it just seemed simpler to not have to overhaul that as well. Plus, given that I am starting from carbon road bike I already own, I want the option of changing the fork out to aluminum if the torque arms don't cut it.

I have been borderline on pulling the trigger on the Bafang G311 from ebikes. I honestly didnt mostly because of wanting a better display than what Ebikes ships with, but maybe should just go that route order a Bafang display elsewhere.

Thank you everyone for the feedback. I'll dig into the different links provided and post what I land on.
 
Thank you for the feedback, many fail to reply with more info about their weight, or stamina, or expectations.

I think a road bike for you with a small planetary geared motor will work. It will coast good enough, the resistance you will feel will be just weight.

Front is easiest, but it does change how the bike feels when you pedal more than a rear motor. You get used to it fast. Chances are, you will like it enough to ride with at least some assist all the time. It's just addicting, but if you get a system that allows a very low level assist, then riding in that level all the time won't eat up the battery too fast. This will work to eliminate the feel of the extra weight. ( perhaps 15- 20 pounds added to the bikes normal weight) Do get a decent size battery, 36v 10 ah or so, so you can do long enough rides using the assist at higher levels only on those hills.
 
Coming back, the Q* ones had looked on point, but had seemed.problematic from a quality perspective...am I dismissing them to quickly?
Yes you are. Motors, irregardless of make or type are the most reliable component in the system and you are more likely to have a problem w/ the controller, wiring or batt. The batt. is the big ticket and most important purchase decision. Often, in an effort to consoldate shipping costs, where you buy the batt. dictates where the rest of the system is purchased.
The rollers looked...more concept than practical. I hadn't seen much personal reports on them to make me.feel comfortable with that route.
Sprag clutches have been around since at least the 1940's, probably longer.
The real decision on mini motors is the type of gear-set it will mount. Many of us prefer the "C" or "CST" types that mount the donor bike's cassette (or another w/ the sm 11T gear), rather than have to buy a pricey and rather heavy DNP free whl. This limits the choices.
If a sm geared mini-motor assist system is the way you want to go, The battery, the vendor and the type of controller are the primary decisions.
The motor speed range is the important decision as to the motor and as we have been talking about, the "C: motors only seem to be available in low and high speeds. From your description of your riding style, you would want a low speed motor. A 201 in a big whl. will top out around 20 MPH on 48 Volts. Bumping the pack Voltage to 52 will raise that a couple MPH and is a very nice combo.
Generally, if there is any extra funds that can be used, it is recommended to put them in the pack (for name band cells, for example).
 
Regarding front / rear, I am fine with unnatural (at least unless I end up having to accept low level pedal assist after more test riding) because of when I am looking to engage the motor.
A frt. mounted mini is not particularly "unnatural" feeling if the system power is low, say below 1000 Watts. The only scary moment I ever had w/ a frt. mounted motor was when I was standing by the bike and bumped into the thumb throttle. I have run as much as 1500 Watts on one and then things can get a little hairy. The tire can start to spin on less than optimum surfaces for one thing. As with all frt mounts, strict attention must be payed to installation, things like hardware mounting surface and torque arms.
The installation seemed fine enough, but a lot of motors end up not leaving room for my existing drive train (10 on rear), so it just seemed simpler to not have to overhaul that as well.
Once the system is installed, most of us do little shifting. Even on my low-powered bike, i use 3 gears max most of the time. The frt. chain ring is never used and in fact, most of it is removed to make more of that all important h.bar room. I use a left-hand throttle to keep the rear shifter original.
Plus, given that I am starting from carbon road bike I already own, I want the option of changing the fork out to aluminum if the torque arms don't cut it.
I would recommend NOT starting out w/ a carbon bike. Like shifting lots of gears, super lightweight is not much of a consideration on an ebike.
As quality is important, starting ew/ a WallyWorld bike may not be the best idea, but a quality older bike that might be considered too heavy by serious bicyclists is not a problem at all with a motor.
Used models that have fallen behind techicaly for cycling are the best values in ebiking.
In fact, out of favor 26" wheels work very well w/ hub motors.
 
Given your fairly low amount of riding annually, I think that you are likely to find that you'll be running some kind of power all the time once you get the bike converted. What adding a motor tends to do is expand your range and inclination to ride since doing so isn't necessarily a physical ordeal. This happens because riding at 18-20 mph for a moderate effort is just more fun than riding at 12-14 mph. And once you start riding more, your fitness will improve because you find yourself putting in a moderate amount of effort all the time and riding more. And once your fitness improves, you find yourself pushing harder - especially up those hills - because it is fun. The more fit you get without killing yourself encourages even more riding. This is the feedback loop that I found myself in after converting my bike. Of course, there is a diminishing return and you will eventually reach some kind of "stasis". But it will be one where you are more fit and happier if you are like me.

If you end up in this kind of situation, then the ride-ability of the bike without the motor powered becomes less of an issue. But a geared motor will certainly leave the bike quite rideable - more so than a larger DD hub motor. I'll leave it to those with more experience if it makes sense to put a low powered motor on a composite bike. I don't think I'd put on on a composite fork though. But that's just my gut speaking. Were it me, I'd probably just look for a nice used steel or aluminum road bike and convert that. I'd leave my original bike alone. You may be shocked by the experiential difference after riding the ebike for a few months. :shock:
 
I have both a motorized bike and a solely human pedaled bike. The latter became part of my quiver only because my fitness level improved from riding the motored bike so much. :lol:

If I had every DIY ebike skill available to me (which I don’t) I’d convert a nice carbon or aluminum road bike with a friction drive using a super small phase runner or those Esk8 centric controllers. Either buy those small cube style batteries or DIY a hobby type Lipo brick pack or DIY xx700 cells & BMS. :wink:
 
guyrandom1 said:
I have been interested in building a small hub motor ebike as a road bike conversion. I have been an off and on bike rider, so have a road bike that I am looking to augment with a small motor to give it an occasional boost (throttle only), but intend to ride it 99% of the time on pedal only. As such, I am fine with lower power (250W or so), and am thinking front hub. For simpler build. I am wanting as light as possible to keep the experience as close to traditional road bike as possible. Stealth is nice, but secondary really to weight and maintaining a traditional experience

After looking at my options, the one I had settled on was the Bafang G370, but am having trouble locating a vendor. There are a handful of options on Alibaba but all require larger quantities. Anyone know of a vendor for these? Any other recommendations?

G370 201rpm is available form topbikekit $185.
 
FWIW, I was an off and on rider too for years. A few weeks after I got an e bike, I was riding with power 99% of the time, and commuting 15 miles one way to work.

a year of that, and I was riding pretty long distances on mountain bikes, on very tough trails.

Start small very good. Keep it cheap. But don't be surprised how much you feel like riding when the hills and the wind get easy. Or how much you can shape up using power 99% of the time. Just pedal what is comfortable, and see what happens.
 
OP asked about the Bafang G370, which is a 1.7 kg motor, sort of in the same class as a Bafang G310 only smaller and lighter. People seemed pretty excited about that particular Bafang motor a year ago, "Cutest little hub motor on the planet", and I have been really thinking about it myself, yet there seems to be very little discussion of the 1.7 kg G370 either here or anywhere else that I can find. So I am wondering what happened? Has anyone tried the 370? Does it have problems? I have read the earlier thread which suggests the promise of the 370, but not seen much follow up to speak of and almost no one comments on the 370 here despite the OP mentioning it. Anyone have any news, perspective on the 370??
 
OP asked about the Bafang G370, which is a 1.7 kg motor, sort of in the same class as a Bafang G310 only smaller and lighter. People seemed pretty excited about that particular Bafang motor a year ago, "Cutest little hub motor on the planet", and I have been really thinking about it myself, yet there seems to be very little discussion of the 1.7 kg G370 either here or anywhere else that I can find. So I am wondering what happened? Has anyone tried the 370? Does it have problems? I have read the earlier thread which suggests the promise of the 370, but not seen much follow up to speak of and almost no one comments on the 370 here despite the OP mentioning it. Anyone have any news, perspective on the 370??
 
I'm replying for the sake of the archives.

I have a G370 on my commuter bike, it was an upgrade from a G31x to get a lighter and more compact motor.

Something to be aware of: the G370 won't fit with some dropouts, it is best with fork dropouts that are on the inside of the fork blade (instead of centered on the fork blade).

The higher motor speed compared to the G31x makes it louder, it has a whine that I don't love. If you aren't sensitive to high frequency noises it won't be an issue. I've only run it with a Baserunner and have max phase amps set to 30A (about 25% less than with a G31x). I'm running it with a pair of LiGo batteries.

Besides the noise it works well. I lives up to the promise of being a lighter and more compact alternative that still has plenty of power for regular commuting. I like low power motors and use G311s on cargo bikes -- riders who prefer high power motors probably won't like the G370 very much.

I've taken the G370 apart and it's built very similarly to the G31x motors, it is just smaller.
 
The G370 built in to my bespoke Cotic Roadrat, I finally finished the bike yesterday having started it in April 2020 when I acquired the frame only.
Thanks to the lightweight hub and the low 14:6 gearing it runs unpowered very nicely, though a 36v 201rpm spec I'm running this with a 12s hg2 diy drinks bottle battery and a 22a 9 fet KT.
The hub rides nicely with me fully clothed at about 190lbs and two panniers chocabloc with food shopping to the value of £32 sterling or approx. $43/44 US.

The battery I have been using with a 270/300 rpm 8fun CST and on a heavy bike returns a useful 25-30miles range, this of course is in low PAS 1 use with KT controller, more then enough power for me riding flat terrain at up to 20mph. The assist cut off set to 16.5mph.

G370.JPG
 
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