Quiet please

[Poppa Kohl]

What is the best set-up to run silent. Some of the set ups shown on U-tube makes a very nasty noise. Some claim a direct drive is quieter than a gear drive. RC motors appear to "screem". I'm thinking that a freewheeling geared rear hub is about as quiet as they come. What do you guys say?

 

[Rifle]

The amped motor guy claims the geared motor he sells is as quiet or quieter than the 9C direct drives he sells.

 

[mrzed]

Ebikes.ca also claims that the crystalyte 400 series are about the most silent thing out there. I'd trust them.

 

[madact]

Direct-drive is theoretically the quietest, but that depends on how it's driven - I'm guessing most controllers out there are BLDC - style switchers that just give all or nothing to the coils - you really need a controller which produces sinusoidal waveforms for quietest operation, but this requires more expensive transistors with higher switching speeds, a buck topology with the motor coil as the load, and some real smarts in the controller. With a sinusoidal waveform, gears and imperfect motor balance would be the dominant noise source in a geared hub. A square waveform of the switched current will produce all sorts of nasty harmonics. For the ultimate in quietness, direct-drive with a current waveform tuned to the motor could be made for all practical purposes silent.

Gear-drive will have an advantage over direct drive with a standard controller simply because the motor is better acoustically decoupled from the outside of the hub.

 

[docnjoj]

I just bought a 9C because my Bafang, while not really noisy, does have a gear whine. I would like to hear a recording of that gear motor Amped Bikes sells because if it really is quieter than the 9C or Crystalite I would get one! My wifes brushed C/L is virtually silent! I am really noise sensitive but love gear motors for the light weight and lack of unsprung weight on my rear suspension. The 9C is not light so we will see!
otherDoc

 

[justadad1957]

i have 3 mini geared ebikes now a 700c rear from hi tech bikes and from amped bikes a 26 front and 26 rear
all 3 are very quiet at 36v some gear noise under full load more so with the 700c kit as it had i believe the 15 amp control
instead of the ? 22amp one that came with the ebike kits
the 15 amp control on the 700c wheel didnt seam to want to pull up to top speed
after.. well with some slight mods to the shutView attachment 020.JPG
i did clean up the solder joint some
now at top speed there is no noise differance between the bikes
and the 700c is the fastest by 1/10th mph lol
maybe 27mph hoc 23 at end of charge running 16s6p 18650 cells
now that i have tried it at 16s and there was no magic smoke coming out
it would be so hard to go back to 12s even thought i know it would extend my range by going slower
36 volt is less noise.. than 48v but only under full load once you are at speed the only thing you hear is wind and your tires

 

[dogman dan]

My quietest motor is similar to the clyte 400 series motors. The aotema motors sold by High Tech Bikes. Nearly completely silent, except at start up. I find my 9c 6x10's quieter than my 9x7's. The 9c's seem to make a slight buzz even at full speed. The more load the more noise on all of em.

Noisiest of all would be either curries or heinzmans. Planetary gear motors do make some noise, enough to be noticed as a motor. But not reminding you of the dentist like the heinzman.

 

[tycreek]

What kind of performance expectations are there of "quite"?

 

[morph999]

I'll 2nd the crystalytes. I got a 5303 crystalyte and it's very quiet. The birds don't even hear me coming.

 

[TPA]

406 here, absolutely not a sound...from the motor

 

[madact]

406 here, absolutely not a sound...from the motor

WHHHHEEEEEEEEeeeHAAAAAAAaaaaaaa! (fwooommmm) :lol:

 

[EVan]

Direct-drive is theoretically the quietest, but that depends on how it's driven - I'm guessing most controllers out there are BLDC - style switchers that just give all or nothing to the coils - you really need a controller which produces sinusoidal waveforms for quietest operation, but this requires more expensive transistors with higher switching speeds, a buck topology with the motor coil as the load, and some real smarts in the controller. With a sinusoidal waveform, gears and imperfect motor balance would be the dominant noise source in a geared hub. A square waveform of the switched current will produce all sorts of nasty harmonics. For the ultimate in quietness, direct-drive with a current waveform tuned to the motor could be made for all practical purposes silent.

I tried my 9c motor with infinion controller on the bench last night. When you apply just enough power to turn the motor gradually, I was surprised to be able to hear a noticeable "click-click-click" as it turns, very like a freewheel. If you load the motor by slowing it with your hand, the sound gets louder. At faster speeds this turns into the familiar whine.

The click must be at the commutation point, slight movement of the windings or perhaps even a tiny amount of play in the bearings, as the magnetic field changes position.

I think you are right that a sinusoidal drive is the answer for complete silence!

 

[dogman dan]

Both my 9c's and my 5304 have that very slightly audible click as each magnet is passed by the rotor. In use it makes a barely audible zzzt zzzt sound that turns into a hard to hear zinging sound at speed. It may be audible to pedestrians, but for the rider wind noise drowns it out.

Only my gear motors made just enough noise for pedestrians to turn their head going "what's that coming?"

Under a heavy load, like an uphill start, the 9c's and others will make a kind of grunting noise that is not that loud.

 

[AussieJester]

RC motors appear to "screem".

Just so happens i took a video of my RC Motor today to show
the whistling noise it makes idling at slow speed, the wide
open throttle scream is sweet when your flying along ...

[youtube]8q20uEmZa5g[/youtube]

Obviously if total silence is your goal though the RC Outrunner isn't the
better option.

KiM

 

[docnjoj]

No,no, no! Please don't do that again AJ! I'll talk! I'll tell U every secret I know. Please don't make that noise again!

That scream would drive me wild! I like the spinner on the end of the motor!
otherDoc

 

[AussieJester]

No,no, no! Please don't do that again AJ! I'll talk! I'll tell U every secret I know. Please don't make that noise again!

That scream would drive me wild! I like the spinner on the end of the motor!
otherDoc

I been thinking of some sort of vains on the end to make it louder actually Doc ...
more i can get it sounding like a turbine the better. :wink:

KiM

 

[docnjoj]

What? I can't hear you, AJ. I love standing next to jet engines at full throttle! Great fun! I need SILENCE! Sorry for the rant.
otherDoc

 

[Poppa Kohl]

That is one sweet set up! I couldn't drive it thru the church on Sunday - but it is quiet! One ponders what it would sound like with chains instead of the belts. Just great engineering.

 

[John in CR]

The only thing I hear is the wind and tires, but if I listen closely I can hear the click of the freewheel though after 10k miles ofr freewheeling the pawls are so worn smooth that it's quiet for a freewheel. Direct drive hubs rule, though I understand the 9c is subject to some ringing. I wonder if Ypedal's epoxy treatment stopped the 9c noise.

It just can't imagine riding one of those vacuum cleaner bikes.

 

[johnrobholmes]

I would concur that the 40x Xlyte motors are likely the quietest. The 9c is very quiet at full throttle, but do get grumbly at low throttle because of the controller switching- loudest around 18mph from my experience. For low power levels, the bafang motor is pretty quiet too. On 36v I can't really hear it except at low speed.

 

[docnjoj]

The only thing I hear is the wind and tires, but if I listen closely I can hear the click of the freewheel though after 10k miles ofr freewheeling the pawls are so worn smooth that it's quiet for a freewheel. Direct drive hubs rule, though I understand the 9c is subject to some ringing. I wonder if Ypedal's epoxy treatment stopped the 9c noise.

It just can't imagine riding one of those vacuum cleaner bikes.

Hey john! Tell me more about ypedals epoxy treatment of a 9C. I have been thinking that if it is still too noisy I might stick some aircraft sound deadener on the side. Then I gotta monitor temperature though because it is insulative stuff.

 

[amberwolf]

Just so happens i took a video of my RC Motor today to show
the whistling noise it makes idling at slow speed, the wide
open throttle scream is sweet when your flying along ...

Obviously if total silence is your goal though the RC Outrunner isn't the
better option.

Although if you make it louder and run it long enough, *everything* seems quiet afterwards. Permanently. :lol:

 

[spinningmagnets]

docnjoj, here's a thread about experiments to quiet the 9C, it seems to have a resonance under acceleration, but is apparently very quiet at a steady cruise (if using certain controllers). Speculation its the large thin side-plates...

http://endless-sphere.com/forums/viewtopic.php?f=2&t=13971

Though Kepler is known for his RC friction-drive, he mentioned that he had a Crystalyte 4XX that he ran at 100V. Very quiet and powerful at fairly low amps, due to the higher voltage. Didn't mention details about the battery or controller (IIRC)

 

[AussieJester]

YPedals JB Weld treatment did absolutely squat for the noise of the 9C IIRC...

As to the noise of the outrunner it''s nowhere near as loud when your riding it i had the camera a foot away from it in the video for alot of the time.
Go ride some 2 stroke Moto-X bikes then my outrunner sounds very quiet, hence i would like it a lil louder, i guess its time to start experimenting with small fan on the front of the outrunner?

KiM

 

[docnjoj]

Thanks S/M for that thread info. My 9C arrives Monday and I will soon see if the noise is noticable to my sensitive ears. If it is a harmonic from the side covers perhaps a bolt or 2 in the right place (prolly at least 2 for balance) might help. I also have an old C/L analog controller to change out for the infineon to see if that helps. Stay tuned!
otherDoc