The three noises of the CCS motor - one not normal?

[Fran Fabrizio]

So, I've had my bike for a while now (700 miles or so of riding this spring). My motor definitely has three distinct noises:

• The baseline hum of the motor whenever engaged, which does increase in pitch and loudness as speed rises
• A subtle harmonic "whirring" sound at higher speeds. It's actually kinda pleasant.
• A much louder buzzing that I can only describe as part weed trimmer, part electric shaver, which comes on suddenly and goes away suddenly after a few seconds or more. Usually appears at higher speeds but can rarely appear from a dead stop. Usually appears when under more load (accelerating, on a hill, or accelerating on a hill but can rarely appear while cruising on flats. Seems a bit louder / more frequent in higher assist modes but I've heard it in all modes. Will hear it lots one week and barely at all the next. I can feel vibration through the bike seat when this noise is happening. I don't recall hearing this sound at all for the first 400-500 miles.

That last one is the one that worries me, of course. Captured on video here: https://photos.app.goo.gl/aTmuAV5cLcPIbS7J3 The harmonic whirring is subtle at 15-22 seconds and 23-31. The louder buzzing is not at all subtle from 9-14 seconds and again from 42-47 seconds. I think I had the camera pointed into the sun for the first half of the video so it's a whiteout for a bit, sorry. I was in assist level 2 on a flat street when I captured this.

Thoughts? Time to open a support ticket with Juiced? If it were consistently getting worse or more frequent it would make more sense to me, but it comes and goes. I know that motors can go through transitions as they break in, but it doesn't sound great.

 

[Bruce Arnold]

It doesn't sound any different from a sound my CCS occasionally makes. We've been discussing this on another thread -- don't remember which one. @Reid and I have both had similar experiences in which the motor sometimes makes louder noises. Stop pedaling and start again, and the noise is gone. Reid is of the opinion that it has to do with how the gears of the motor mesh. I don't have the knowledge he has but that seems to fit with how my bike behaves.

Why not put in a ticket with Juiced, and send them that video?

 

[Reid]

Sounds just like mine.

These things are planetary geared reduction motors and depending on the luck of the draw when power is engaged, the drive may be virtually silent, or any degree of vibratory whine.

When the engagement is whiney on my bike (for example, yours may be a lot different), I stop pedalling for a moment and try engagement again. One out of three engagements (lucky me) is virtually silent and nobody, including me as the pilot, hears the motor.

Planetary gears' engagement with the sun gear must be extraordinarily perfect or gear noise results. It is amazing how quiet a Bafang hub motor can be if it is a lucky example and the engagement is made at the right, relative time.

The Model T Ford lives with an always-engaged planetary transmission, the hardened steel planetary gears constantly whirring around a hardened steel sun gear when the drivetrain is in "neutral" and also in "low." Most Model Ts, therefore, sound like coffee grinders when idling. One-in-so-many will be almost silent! The late Garland Poblett's 1915 Touring car was not perfect like my '22 coupe was, but his was SILENT. And mine made a normal, T whine, try though I did to make the running tolerances perfect. Go figure, says Luck.

It is the luck of your Bafang motor's being in the sweet spot of ten-thousanths-of-inches differences of the epicycloidal ideal of spur gear tooth rolling engagement profiles. The least little lack of practically perfect tooth engagements generates a lot of entirely harmless but annoying noise and vibration.

 

[Fran Fabrizio]

Thanks for the background info (I strongly suspected @Reid would have the scoop on this!) My only concern is if this goes from occasional to constant. Yesterday The Noise (tm) was present for at least half of the 11 mile ride, despite frequent motor pauses. Will wait and monitor the situation some more.

 

[Chris Hammond]

I agree with the others. This sounds like my bike as well. It seemed to me that the noisy sound you are talking about is when you are accelerating from a slower speed, and the load on the motor is higher than at other points.
I'd learn to ignore it, or try using lower assist levels when accelerating.

 

[Bruce Arnold]

http://juicedbikes.happyfox.com/kb/article/3-motor-rhythmic-sound


@Fran Fabrizio Here's some more information about the motor noise. Ran across it looking for something else. Ain't that just the way?