Quit your whining : How much ebike motor noise is too much?

October 14, 2019

I’ve ridden every single ebike I can get my hands on in the last 5 years. So are fast, some are slow, some are big, others are small but one thing that all ebikes have in common is that they are vastly more quiet than their internal combustion cousins. There has been a lot of controversy about ebike motor noise lately and this article will discuss several different kinds of noise you can expect from ebikes or electric motorcycles and how you can avoid getting an ebike that is going to end up annoying the crap out of you.

The chain on the Sur-Ron Light Bee is much louder than the electric motor is

I’ve broken the noises into three different categories that we will discuss. Motor noise, gear noise and chain noise.

Motor Noise

Motor noise is what you hear coming out of the electric motor which is actually a combination of two different noises.

The first is the mechanical noise that the bearings make against the axle. Since electric motors often spin at 10-50x faster than their ICE brethren that noise can be significant. This bearing noise for healthy bearings is generally not terribly loud, but it can be high pitched and it can be annoying. With failing bearings the noise tends to get extremely high pitched and gets incredibly annoying. Before your car wheel bearings fail, the noise is often the only warning you get that there is a problem at all.

The M600 from Bafang was a flop until the nylon gear got replaced with a steel gear, the only real issue now is that the steel gear made it noticeably louder (video of ride noise here)

The second noise you hear from an electric motor is the ‘coil noise’. Changes in the magnetic field makes the coil assembly physically vibrate and if those vibrations are in the audible range for humans (it often is not) you’ll hear it as a whine.

When designing electric motors often a great deal of effort is put into acoustics and vibration damping

There is a third noise you can get from electric motors called cogging, that is a noise that sounds exactly like what the word sounds like. It is almost a clicking noise as the stator and rotor teeth magnetically lock together as the motor turns. I”ve had one older large cheap Direct Drive hub cog, but every other electric motor I’ve seen has not had cogging noise so it’s just mentioned so the article is ‘complete’.

Gear Noise

When gears mesh together noise is made. There is a lot of ways that this noise can be decreased such as

  • Using helical gears
  • Grease or oil
  • Use of nylon gears
  • Special coatings on the gears
This shows the insides of a geared hub motor, the gears are labeled ‘clutch’

Every ‘geared hub’ motor I’ve used has always had three nylon reduction gears. Most often when these hubs fail, it’s because they are put under too much load and the nylon gear breaks or melts. Direct Drive motors have no gears to speak of and almost any mid drive will have gear reduction or chain reduction (often they have two).

In a week or two you will be able to buy a replacement steel gear to replace the venerable nylon gear in the BBSHD

The best thing I’ve found for reducing gear noise is a liberal greasing. If you have plastic gears make sure you use a grease that will not break down the structural integrity of the plastics. If the grease is black, it’s probably the wrong kind for nylon. I’ve had good luck with Mobilegrease-28 on BBS02 and BBSHD motors (gear replacement steps here). Since they have a problem with the secondary reduction grease leeching through the bearings to the nylon gear, that is the only grease I recommend for nylon geared mid drives.

Chain Noise

Any chain is going to make noise, the bigger it is, often the noisier is is. The #420 chain on a Sur Ron is going to be way more noisy than a single speed bike chain and a single speed bike chain is going to be generally noisier than a 8 ,9 or 10 speed chain. This is not always the case, because often bikes with many gears will have a screwed up chain line when in your granny gears. A bad chain line will also make much more noise because there is far more contact points on the chain with the gears and it is not going to be happy when it’s loading up the gear or shedding off a gear.

Good chain line, bad chain line, there will be a test

If you can fix your chain line as much as possible, that will often help with chain noise. Ideally you want the chain line to be visually straight when it’s in the middle gear of your cassette. That is not always possible, but that is what you should shoot for.

They do make ‘low noise chains’ but I have never seen an ebike with one

If you can get a bike with a belt drive it will be much quieter. Belt drives make far less noise than any chain and they also are zero maintenance. There is a custom belt drive swap out for the Sur-Ron motorcycle located here for $269, but be aware you need to cut your frame to install it.

The Gates Carbon belt drive is the ‘Rolls Royce’ of ebike drive systems

Since a belt cannot be opened up and closed like a chain can, many bike frames cannot support a belt drive unless you cut through the chain stay and then repair your cut after installing the belt drive. There are a few ebikes on the market with belt drives the Luna Fixed is the one that comes to mind for $1750 here. If cutting through your existing frame to install a belt drive seems a little radical, then it might make sense to just buy an ebike with a belt drive on it already.

Top 10 hits : How loud is it anyway?

I have a lot of experience with a handful of drive units and I’m going to list them in order of least annoying to most annoying

  1. Most low powered geared hub motors I’ve tried and destroyed
  2. BBS02 (nylon gear)
  3. BBSHD (nylon gear)
  4. 1000-3000 Watt direct drive motors (high pitched whine)
  5. M600 (steel gear)
  6. Ultra Max (steel gear)
  7. Cyclone 3000W (chain reduction)
  8. Sur-Ron Light Bee eMoto (420 chain)
  9. Tangent Ascent 3000W (cycloidal reduction)
  10. Tangent Ascent 6000W (cycloidal reduction)

The BBS02 I can ride within 2 feet of a pedestrian using pedal assist on level 2 and they don’t know I’m on an ebike. With the Sur-Ron or a cyclone that would never happen. I’ve also noticed that the higher pitched the noise is, the more it tends to get on my nerves. Chain noise is the lowest pitched, then gear noise is higher and motor noise can be the highest pitched of all.

The award for quietest ebike motor system goes to the 750W nominal 1200W peak BBS02

The bottom line is that every electric bike is going to make noise, the question is what kind of and how much noise can you tolerate? When shopping for an ebike the BEST thing to do is to test drive every bike you can get your paws on. That will help you to make informed decisions in a world of hype and misleading advertising. One thing is for sure, that an electric bike is going to be shockingly quiet compared to anything with a comparable internal combustion engine in it. Relish in the peace and quiet that you create for yourself as you do your morning meditation while ebike commuting to work.

Ride on.

What’s your experience with noise and ebikes? Leave a comment below and share your wisdom with the world.

The Luna Fixed is the stealthiest of stealth ebikes and comes with a Gates Carbon belt, they’ll never hear you coming (perfect for evading Zombies)

Karl Gesslein is a degenerate hooligan of the highest caliber living in upstate NY. His passion for e-bikes and all things sustainable causes him to be obsessed with climate change and finding solutions that will keep humanity from becoming extinct from our own hubris. His personal blogs include electricbike-blog.com, awaken-spirit.org & chestnutparadise.com.


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