How loud are the RC motors?

[RayB]

Hi Guys,

I am really considering converting one of my bikes to an RC setup. It would be a low rpm unit using a cog placed onto the disc brake mount on my alphine internal hub. My query is. How loud are these things compared to say like the cylone kits or similar type non hub motors. Anything out of the ordinary will draw attention to me as I commute where I live and dont really want the fuzz annoying me on a daily basis. Are they as high pitched as I imagine when at a constant speed... say 20/30km p/h.

Thanks...

Ray

 

[Grinhill]

Mine is definintely louder than a hub motor, but I would say it would be a little quieter than a Cyclone (no gear noise).

Most of the noise you hear is the high-pitched whine of the windings at whatever frequency they are being driven at plus harmonics.

 

[kentlim26]

Mine is definintely louder than a hub motor, but I would say it would be a little quieter than a Cyclone (no gear noise).

Most of the noise you hear is the high-pitched whine of the windings at whatever frequency they are being driven at plus harmonics.

Hi Grinhill,

Rc motors or the cyclone one. Noise can be reduced by building a cover/ container cove around spining areas. you will hear noise is lower.if there is nothing around the spining area sound is certainly louder like a engine 50cc.

 

[swbluto]

An RC motor is *definitely* not as loud as a 50 cc engine. But, yes, covering it should muffle it.

Anyways, what I hear is a "whir" like a drill that increases in pitch as it increases in speed. It, however, really isn't that loud as a standard drill, it's like "half" as loud as one if you can imagine what that is. What I've found in superbly quiet surroundings, people can't hear it until it's about 30 feet away. On campus where there's the aural environment of chatter and shoes slapping the pavement, people don't seem to hear it until I'm about 10 feet away. Whenever I'm around a running standard gasoline vehicle, I can barely hear it. I think the most drivers notice about my vehicle is the wires that stick out of my backpack and my unusually high speed for a tiny seeming "kick scooter". They can't hear the motor at all, and I really doubt they could hear it if they rolled down their windows.

But, yes, it's definitely louder than a hub which is basically silent. But it is nowhere near as loud as a gasoline vehicle, particularly almost all 2-stroke engines that seem to populate gas scooter and gas bike kits.

Anyways, I think someone should do a noise comparison test using video. I'm also really curious what my scooter sounds like at a distance. I know that I can definitely hear it, but my ears are 5 feet away from the motor! Someone standing 10 feet away. would hear it to be "8 times as less" which is nearly 10 decibels, which basically sounds "half as loud" according to common perception. 25 feet away would be 125 times less loud which is near 21 decibel reduction, which means it'd sound "fourth as loud" according to common human perception.

My set-up is a simple belt drive. A chain setup would be a lot noisier.

 

[recumpence]

Here is one of my bikes. Bear in mind, this bike as two motors and is chain drive right off the motor shaft. So, pretty much any RC setup would be quieter than this.

[youtube]DtcTYmI5tfA[/youtube]

Matt

 

[swbluto]

Here is one of my bikes. Bear in mind, this bike as two motors and is chain drive right off the motor shaft. So, pretty much any RC setup would be quieter than this.

[youtube]DtcTYmI5tfA[/youtube]

Matt

Interesting. At around :53, it sounds like you're louder than the motorcycle that's passing by even though it looks like he's only a little further away. I'd find it surprising but... is your bike typically louder than an average motorcycle?

 

[recumpence]

My bike under hard accelleration is louder than a muffled motorcyle at very low RPM.

Actually, that motorcycle was about 30 feet away from me. Also, higher pitch sound comes in louder than low pitch sound.

The throttle blip at the very end of the ride in the driveway gives you an idea of the sound.

Remember, this is two motors with chain, not belt, drive. Most RC systems would be very quiet, but still with a muffled whine.

Matt

 

[liveforphysics]

Mine sounds kinda like a combo sound of a vacuum cleaner, and a cordless drill, but louder than the cordless drill, but quieter than a vacuum cleaner. The noise really isn't a bother to me at all, and when i want to be silent, i just coast.

 

[MitchJi]

Hi,

Interesting. At around :53, it sounds like you're louder than the motorcycle that's passing by even though it looks like he's only a little further away. I'd find it surprising but... is your bike typically louder than an average motorcycle?

1. The PK is passing close to the camera and the motorcycle is relatively far away. The same audio level at twice the distance has something like (I forget exactly) 1/4 the volume.

2. The PK is accelerating at close to the max. The motorcycle is loafing along.

3. The PK is winding up to close to its max speed.

 

[John in CR]

Sound decreases at 6db per doubling of distance, and about a 10db difference is perceived as doubling.

John

 

[northernmike]

I'm pretty confident that most of the noise of the PK is drive chains.

My Motobecane conversion with an HXT 80-100-B and a belt drive was TOTALLY quiet. I did mount the motor in an aluminum tube, but even on the bench it wasn't a screamer.

Especially compared with the 50cc that I replaced.

Miles could tell you the noise levels for a toothed belt drive - I bet his Moulton is pretty quiet.

I don't think you'll wake up the neighbours if you don't want to.

A belt drive with a sprague-clutch bearing would probably be dead silent - no freewheel pawls and no chain links!

 

[RayB]

great thanks guys... my issue is that certainly anything out of the norm over here as I scream past the 20 small police boxes on the way to work attracts attention. Being a huge foreigner also doesnt help. I have some decisions to make....

 

[Miles]

Miles could tell you the noise levels for a toothed belt drive - I bet his Moulton is pretty quiet.

Yes, never had a pedestrian notice it, yet.... even in the park. This is with a maximum motor speed of 1800 rpm, though...

 

[Drunkskunk]

My Motobecane conversion with an HXT 80-100-B and a belt drive was TOTALLY quiet. I did mount the motor in an aluminum tube, but even on the bench it wasn't a screamer.

How you liking this thing so far? and what kind of range are you getting?
I'm seriously considering pulling the motor out of my Peugeot this summer. I just don't ever ride the Pug when I have a faster Ebike available

 

[northernmike]

Ditched the HXT for an eTek - just finished mounting it.

In my opinion, greater launching power is required for a heavy moped conversion.

Dual motors might solve this, but being unwilling to pedal to start led me on my quest for torque.

It did outperform the gas engine handsomely till I overvolted it and let the smoke out of my HV 110.

I might just be power-hungry, but I'm OK with that.

 

[recumpence]

I might just be power-hungry, but I'm OK with that.

Yea, baby!

Matt

 

[Drunkskunk]

Ditched the HXT for an eTek - just finished mounting it.

In my opinion, greater launching power is required for a heavy moped conversion.

Dual motors might solve this, but being unwilling to pedal to start led me on my quest for torque.

It did outperform the gas engine handsomely till I overvolted it and let the smoke out of my HV 110.

I might just be power-hungry, but I'm OK with that.

Heh, and I was actualy considering a smaller motor than your 80-100
So hows the Etek mount? got pics?

 

[northernmike]

I finished the mechanicals yesterday - no pics, but I can tell you how I did it.

It's stuck to the bike with a 3/8" aluminum plate mounted to a 3x3", 1/4" wall square aluminum tube, bolted with 3/8-16 stainless, lock-washered and nylock nutted, with the aluminum tapped for good measure.

I used the stock mounting points from the ICE and rubber-bushed everything.

(The stock top mounts use a molded rubber bushing anyway, I used two squares of transformer mounting vibration isolation rubber to make the rear mount "float" without a spring....)

I used a nylon "link belt" - a Fenner Drives Power Twist ("A" profile v-belt for power tools) and a 5" pulley.

The whole assembly clears the front fender by 3/4", the stock side covers still bolt up, and there's room on the right side for the #4 feeds to the motor to be routed inside.

It's even quieter than the HXT, too.

The Power Twist belt is a nice product if you're going for a V-belt drive, for whatever reason - something Miles advised me was low efficiency. The flexibility reduces noise, but I don't know if it improves efficiency or reduces it compared to a standard V-belt.

I realize this is a compromise, but pictures later will prove my rationality!

I did this so that I could keep the bike as stock as possible - I could unbolt my drive and bolt it right up to any of the 14 million Motobecane mopeds (well, the popular 40T, 40V and and all the 50 series models anyway) - just remove the ICE, bolt this up, and go.

It was so cool to realize I had the reduction drive I needed in this frame that I didn't bother re-engineering it. I got an aluminum driven pulley and the best belt I could for the format instead.

I'll update my build log when I get some pics.

Sorry to hijack this thread!

 

[swbluto]

Make sure to post a link to your build thread when you make it.

 

[GTA1]

There is a lot more to noise reduction than just the motor.

The entire drive train system, including the tires, and the rider / frame all make noise.

Do a step by step noise reduction program by recording the noise with a good mic and a spectrum analyzer, and then working backwards to kill the source.

Off hand, here are the biggies:

- gears (very noisy) - easy solution, don't have them, harder solution, cut RPM, then wizardry (mating gear surfaces, etc.)

- motor (whine) the high pitch sound is from armature rotating / vibration - easy solution, a housing that dampens sound but yet allow cooling (very important), then, isolation of gear from mounting with some elastic material, rubber mounts (like engine mounts in a car) - a bit of decoupling can be had just by using rubber washers and / or silicone at critical points.

- if you are using a chain, get rid of it for a belt, which is inherently less noisy.

- Tires, pick tires that have less aggressive tread or quieter ones - motorcycle grade tires is great

- after these big ones, you are into controller noise, bearing, wind, etc.

 

[Lock]

With suggestions about shrowding RC motors... I'da thought they rely on air flow for cooling more than other electric motors? True? Or no?