Planning ultralight, stealthy, silent build, questions..

[croowley]

Feels like there´s very little progress regarding hub motors these days or am I missing something? Need some advice.

I found the q100 and Xiongda Ytw-06 to be the smallest viable motors available but these are old motors. Certainly there is some better options going into 2024?
The Ytw-06 takes a maximum 28" wheels, I want to do 29", is this possible and why wouldn't it be?
Is there a way to silence something like the Ytw-06 by filling it with grease? I've seen people fill the q100 with oil for cooling, does it improve the noise levels as well?

More questions to come!

​

 

[Chalo]

It's like you think electric motors are new tech or something. They're not going to magically get much smaller while delivering the same power and torque as they did a few years ago.

There's no reason you can't use a 29" wheel, but the larger the wheel diameter the more motor torque it takes to produce a given amount of thrust at the wheel. This reduces the motor's performance and decreases operating efficiency.

You want a sine wave or FOC controller for quietest operation. Yes, adding grease to the gears will reduce their noise temporarily. You don't have to pack it full, just enough for the lube to be replenished while running.

 

[Chalo]

If I were wanting a small, light gear reduced hub motor for 29er wheels, I think the extra 400g for one with double gear reduction would be well worth it. The Bafang G310 is purportedly very quiet. Just put a humongous modern 1X cassette and a nice large disc rotor next to it and it will disappear.

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

 

[calab]

e q100 with oil for cooling

then it leaks
atf oil right?

 

[richj8990]

Feels like there´s very little progress regarding hub motors these days or am I missing something?

​

You nailed it right on the head. There is 'some' progress here and there. Like taking a hub and putting 1:11 gearing inside, but then leaving it QR bolt-on axled. Or...making a thru-axle hub and then leaving it lower-powered direct drive. They tease us with little tidbits of modern design here and there, and then leave other crucial parts as 20th century.

One thing you also need to take into account is the rest of the bike's weight compared with the motor & battery. Let's say you found an unlaced hub motor that weighs 5 lbs. And the lightest mid-drive that is acceptable to you is 8 lbs.

But that's not the whole story. The mid-drive can fit into a carbon thru-axle frame that's 3 lbs, while the typical QR hub drive frame is more like 5-6 lbs. And the laced hub drive wheel, unless you custom make it, is probably going to be a heavier 3+ lbs compared to a modern tubeless ready wheel that's typically around 2 to 2.5 lbs. So right there with the QR frame and rear wheel you just completely negated the hub motor's lighter weight. Take a good, hard, long look at mid-drive options, the frames they can fit into, and the modern, lighter wheels that can be used. Then do the weight math. And also the performance math.

 

[croowley]

If I were wanting a small, light gear reduced hub motor for 29er wheels, I think the extra 400g for one with double gear reduction would be well worth it. The Bafang G310 is purportedly very quiet. Just put a humongous modern 1X cassette and a nice large disc rotor next to it and it will disappear.

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

I will have a better look at the g310. Any other good options?

then it leaks
atf oil right?

Yes it seems to leak above ~ 50% fill.

But that's not the whole story. The mid-drive can fit into a carbon thru-axle frame that's 3 lbs, while the typical QR hub drive frame is more like 5-6 lbs. And the laced hub drive wheel, unless you custom make it, is probably going to be a heavier 3+ lbs compared to a modern tubeless ready wheel that's typically around 2 to 2.5 lbs. So right there with the QR frame and rear wheel you just completely negated the hub motor's lighter weight. Take a good, hard, long look at mid-drive options, the frames they can fit into, and the modern, lighter wheels that can be used. Then do the weight math. And also the performance math.

I´m actually coming from a 15.2kg mid drive cef50 frame, m820 motor that caught fire
I really did miss throttle thought.. And another cef50 is just to expensive to build again.
New target: ~10kg nimble bike as stealthy, powerful and silent as possible. Pick two right..

I found a lightweight QR carbon frame. Still arguing motors.. Would It be dumb to lace ytw-06 or q100c in a 29ER? How much loss of torque are we talking since they seem quiet strong already and some torque will come from me peddaling anyway?

 

[Bush mechanic]

I will have a better look at the g310

Croowley, my 2c worth on the G310. I bought one of these from ebikes.ca to use on a minimalist bike I ride to and from work nearly 4 years ago, and I've been incredibly impressed with how smooth and quiet this thing is. It basically disappears on a mountain bike as it is the close in diameter to my 11-36 cassette on one side and 160 mm disc rotor on the other, and it is ridiculously light.

Having said that, there is a price to pay: The last part of my ride home is a couple of 10% inclines for a total distance of about 500m, full throttle, after 2km of full throttle city stop-start riding (20A standard controller, on a 14s 52V battery). I weight 100kg, bike is about 20kg, running 26x2.35 Big Apples, and unsurprisingly the result is that I have stripped or deformed the gears 3 times in as many years, and have just installed my 4th set. Suffice to say I'm getting pretty quick at rebuilding this motor - the good news is, it is quite easy to do! Be gentle with the torx screws which hold together the motor covers, they strip very easily.

The helical gears are beautiful.

Gears are about $50 AUD per set for me from Grin, but I found them for about $30 elsewhere, though I can't recall the seller just now.

I'm not suggesting this is how anyone should treat their motor, or that what I am doing is good, but I still love riding this thing for the stealth factor. When the gears are in good condition it barely makes more noise than a DD hub. If I had to make a comparison based on what I have personally owned, I'd probably say the G310 on 20A feels similar in noise and torque to my old Crystalye 408 on 30-40A, although of course the 408 is a lot more tolerant of heat.

I've since found them for sale on Aliexpress too, though I can't vouch for the quality control. If you do get one, as per above, get a spare set of gears to keep on hand, but overall this is a great little motor.

 

[richj8990]

I will have a better look at the g310. Any other good options?

Yes it seems to leak above ~ 50% fill.

I´m actually coming from a 15.2kg mid drive cef50 frame, m820 motor that caught fire
I really did miss throttle thought.. And another cef50 is just to expensive to build again.
New target: ~10kg nimble bike as stealthy, powerful and silent as possible. Pick two right..

I found a lightweight QR carbon frame. Still arguing motors.. Would It be dumb to lace ytw-06 or q100c in a 29ER? How much loss of torque are we talking since they seem quiet strong already and some torque will come from me peddaling anyway?

I'm certainly not an expert on electric motors. Can only go by my so far maybe 6000 mile experience w/electrified mountain bikes.

If the q100c is 350W then peak is probably around 700-750 watts. On pavement that's OK. 14:1 gear reduction is really cool for a hub motor. Let me put it through the motor simulator as 1:11 and see what happens.

OMG the torque is horrible, it's only like 20 Nm. I don't know if I did something wrong, ran it as all 3 options for G310. Other geared hub drives with 36V and 17A limiting didn't go above 34 Nm. The controller that most likely comes with this if it's 36V is not going to be more than 15-17A peak. That's rough offroad for climbing. Regardless of the hub gearing.

I'm not sure if you can run this as 48V and put a better controller on that can handle 30A or more. Otherwise even with the gearing it doesn't seem like it's going to climb very well due to the limiting amps. Again if you are just doing pavement it will probably be fine. On a geared hub drive, I like to do at least 400W up offroad inclines, and even then you have to put in human power WAY more than you do on a mid-drive. So conclusion: pavement OK, offroad I don't think it would be optimal.

 

[glennb]

Feels like there´s very little progress regarding hub motors these days or am I missing something. Certainly there is some better options going into 2024?

The better option is plonking the hub motor in front of the bottom bracket, with a torque sensor and a controller running clever power delivery algorithms.

$100 250w hub motors will never improve, there’s no commercial incentive.
,

The Ytw-06 takes a maximum 28" wheels, I want to do 29", is this possible and why wouldn't it be?

There’s no such limitations. You can build it with any rim and tire you like.

Is there a way to silence something like the Ytw-06 by filling it with grease?

No. It’s noisy by nature, being a high speed inrunner using an overly small sun gear to achieve sufficient reduction ratio. Quieter requires larger cogs spinning slower.

I've seen people fill the q100 with oil for cooling, does it improve the noise levels as well?

No. If you despise the sound of meshing gears, you would be able to have some manufactured from a material quieter than nylon, but it’ll be marginal improvement due to the resonances and you’ll need a sizeable budget. Your most practical option would be a direct drive hidden behind panniers.

 

[croowley]

What do you think about this controller? Would help the stealth factor for sure.. Why does it say 12A on image?

10S/13S 36V/48V15A YG KT 6Mosfets Sine Wave Controller KT Tubular Controller [YG Controller] - $46.55 : Zen Cart!, The Art of E-commerce

Zen Cart! 10S/13S 36V/48V15A YG KT 6Mosfets Sine Wave Controller KT Tubular Controller [YG Controller] - ★★★★★ 10S/13S 36V/48V15A YG KT 6Mosfets Sine Wave Controller KT Tubular Controller 1--Rate Voltage:36V or 48V KT sine wave controller 2--Rated Current:7A 3--Maximum Current:15±1A 4--With...

www.topbikekit.com

With 15a controller, is it possible to use cells with 12.5A discharge? Is it govern by the bms or how does it work? Will need 15A cells or higher I assume?

Can I run the g310 on 14s?

 

[E-HP]

What do you think about this controller? Would help the stealth factor for sure.. Why does it say 12A on image?

10S/13S 36V/48V15A YG KT 6Mosfets Sine Wave Controller KT Tubular Controller [YG Controller] - $46.55 : Zen Cart!, The Art of E-commerce

Zen Cart! 10S/13S 36V/48V15A YG KT 6Mosfets Sine Wave Controller KT Tubular Controller [YG Controller] - ★★★★★ 10S/13S 36V/48V15A YG KT 6Mosfets Sine Wave Controller KT Tubular Controller 1--Rate Voltage:36V or 48V KT sine wave controller 2--Rated Current:7A 3--Maximum Current:15±1A 4--With...

www.topbikekit.com

With 15a controller, is it possible to use cells with 12.5A discharge? Is it govern by the bms or how does it work? Will need 15A cells or higher I assume?

Can I run the g310 on 14s?

That's a 7A controller, that can provide 15A peak current.

 

[Bush mechanic]

Can I run the g310 on 14s?

As per previous comment I've been running mine at 52v (14s) for several years. Can't really comment on the controller you've linked to, but everything on their site looks pretty cheap and nasty to be honest.

I could be misunderstanding what you want, but when you chase extremes in any direction you nearly always experience diminishing returns for both your time and your money - not wanting to discourage anyone from a project, but you just need to be conscious that you are probably going to make it quite hard for yourself for very little gain by trying to shave off 2-3kg, for the sake of an arbitrary target of having a 10kg bike.

I'll be putting together a new light weight stealth bike myself in the next few months. I'll most likely try one of the Shenghi SX2 rear hubs (have not yet tried, but allegedly very quiet like the G310 also with helical gears but very slightly larger and heavier), and either a phaseruner or baserunner controller depending on what I can get hold of, most likely on a small 14s battery. Motor weight is about 3kg from memory, battery and controller etc probably 2kg combined, so the system will add around 5kg to whatever donor bike I get hold of.

Considering how much power you are getting I think that is pretty good value for weight carried. Put it this way - 1-2 KG added to a non-eBike is dead weight which noticeably slows you down, but allowing yourself to add another 1-2KG in powertrain components to a powered bike will give you a very substantial boost in range, power, and reliability.

 

[croowley]

That's a 7A controller, that can provide 15A peak current.

oh yea...




Sure but its also significantly larger. 10kg is realistic according to my estimation using some unconventional methods and a lighter, stealthier, weaker bike will suit my needs better.

hmm back to the drawing board..

 

[nicobie]

Please be sure to share your results with us. This question comes up frequently.

 

[croowley]

Please be sure to share your results with us. This question comes up frequently.

I´ve been scanning all the forums and its quiet depressing to see how how bad the stealth section is.. Found about one bike that I could consider riding myself. Think I´ve figured something out here though and I'm very exited to get started. Will do a build log because I will need input since I'm technically incompetent

Oh man if only the ytw-06 was silent enough..
I will be running a big cassette and rotor, maybe the sx2 isn't to big after all, is it? I certainly do like power... ehh..

Anyway the baserunner seems to be the obvious controller, very flat and could be hidden well even on a slim 1kg frame.
What would be the options?

So does the cell max discharge current (12.5A) hinder me from running controller at lets say 20A? How does it work? I mean can I use any cell to build my battery no matter how I run the controller/motor?

What about displays, can I be without?

 

[nicobie]

Be careful about which cell you pick. Some (alibaba etc) are crap and also can be dangerous.

You can do without a display but they are useful if you want to know your state of charge. the Cycle Analyst currently is the very best as of now.

I agree about using the baserunner.

 

[glennb]

I will be running a big cassette and rotor

To hide the motor?

That’s not happening on a 10kg bike.

Single speed rim brake saves minimum 1.5kg.

Anyway the baserunner seems to be the obvious controller, very flat and could be hidden well even on a slim 1kg frame.
What would be the options?

VESCs are smaller and lighter.

So does the cell max discharge current (12.5A) hinder me from running controller at lets say 20A?

Yes. The max discharge is a thermal limit, not an electro-chemical one. Any cell can do ten times that, but each has a different safe discharge current limit. But there’s plenty of cells capable of 20A, that’s not a sticking point to running a 1S battery.

What about displays, can I be without?

You have to be. Your weight and stealth budgets can’t accommodate it.


I realise you’re getting your head around the options, and probably enjoying the mental exercise, but there is only one option to meet your criteria with your current knowledge base.

The only way to do a stealthy 10kg hub motor bike is single speed carbon road bike with carbon practically everything, including 200g flat or bull bar, 150g levers, 200g post, 130g saddle. It’s all cheap on aliexpress, nothing stopping you.

For cost savings you can get away with aluminium cranks, pedals, brake calipers, and rims, but they still need to be at the lightest end of the aluminium spectrum. Plenty of cheap light wheelsets and cheap old 10sp dura-ace or equivalent parts on the second hand market.

You’re a long way (years) from having the knowledge to conjure anything fancier, so if you want this bike on the road anytime soon then your only option is the AKM-75 motor paired with bottle battery and little lishui or kunteng controller I.e. a plug and play kit.

If you want to shave more weight at the expense of investing more money, time, and effort, then you could buy the 328rpm version of the AKM-75 and power it from a single 18V tool battery via a VESC.

 

[Chalo]

That’s not happening on a 10kg bike.

Yeah, 10kg is a pipe dream. The weight budget or all the other criteria will have to shift. You've made a good case for how to do the "all other criteria" version.

Ultra lightweight bikes, pedal or electric, are massively overrated. There's no way to know how light a bike is when riding it, only when lifting it. Durability, reliability, longevity, repairability, and futureproofness are all things I'd rank way above low weight, and since we're talking about e-bikes I'd also add performance and range. For me it's a very easy call, because low weight works against all those other things I want more.

 

[E-HP]

...and since we're talking about e-bikes I'd also add performance and range.

He could eliminate the range concern simply by adding perpetual motion technology, which seems to be another topic that comes up with the same frequency.

 

[glennb]

10kg is arbitrary, but not entirely impractical.

Even someone not used to riding single speeds could adapt to a light electric SS bike. You need to be able to pedal high cadence (or coast a lot), but with 200W of boost up inclines needn’t be overly light and strong.

I primarily suggested 18v tool battery because they use high power cells, include BMS, and are ruggedized .. but also because they swap out in seconds and therefore enable cheating the scales by stashing spares in a backpack.

 

[croowley]

Really appreciate your answers and yes I do realize 10kg is out the window without the ytw. I´ll reconsider and probably build something more capable with a real fork and stuff.

Hmm 13kg dream isn't that bad either.. or am I still dreaming...
Keep bringing new ideas and input though we need to step up the stealth game

 

[croowley]

Motors 36 spokes, all rims I find within budget are 28 or 32 spokes what´s up with that?

 

[2old]

FME, e-bike motors have been 36, while non-e are 24, 28 and even 32 for lighter weight (fewer spokes). Look to Grin for the best 36h rims.

 

[E-HP]

Motors 36 spokes, all rims I find within budget are 28 or 32 spokes what´s up with that?

36 spokes used the be the "standard", with a few rims with 32 spokes were used for racing to save weight. Stronger wheels used 40 spokes. Besides the strength benefits of more spokes, wheels with more spokes can be rideable longer with a broken spoke, without going too far out of true.

 

[99t4]

Motors 36 spokes, all rims I find within budget are 28 or 32 spokes what´s up with that?

What is your budget?