Noisy Bosch CX drive unit

digiman

New Member
I have recently bought a one year old Cube with the Bosch CX drive unit. I'm really happy with it except for the dry sounding noise that comes from it especially when in lower gears. I have been used to a hub drive unit that just has a whiney noise but this is really annoying. Hoping the forum might help
 

Dmitri

Active Member
IGHs such as Rohloff are a lot noisier in lower gears; that's normal. But where is the noise coming from, the motor?
 

Dmitri

Active Member
IGHs such as Rohloff are a lot noisier in lower gears; that's normal. But where is the noise coming from, the motor?
 
I have recently bought a one year old Cube with the Bosch CX drive unit. I'm really happy with it except for the dry sounding noise that comes from it especially when in lower gears. I have been used to a hub drive unit that just has a whiney noise but this is really annoying. Hoping the forum might help
Hi Digiman,

The Bosch Performance Line motors should have a relatively quiet whirring noise. Remove the chain from the front sprocket, so you can crank the motor both ways by hand. You should be able to hear and feel what's going on a little better?
When you crank the motor forward it will spin the crankshaft bearings and the main motor bearing (These are the most common bearings that are likely to give initial problems) When you crank the motor backwards it will only turn the crank bearings and not the main motor bearing.
There are other bearings turning within the motor while you are doing this, but it's a good way of determining if it's the more common main motor bearing.
 

digiman

New Member
I spoke to the Bosch people at the Birmingham cycle show and they suggested that I took it into a Bosch / Cube main dealer and that they would then get a replacement motor assembly from Bosch. I did that and lo and behold 2 weeks later I had my bike back fitted with a replacement motor at no cost to me. That's what I call service and its a lot quieter than the old motor.
 

batmick1

Active Member
I’ve been riding my Haibike with a CX drive since March of 2018 and just passed the 10.000 mile mark. Sure enough, earlier this week it started getting much louder than it used to be and also has some sort of modulation on the whine, especially under light to medium load.
Check the attached video.

I can’t feel any roughness and there is no play in the cranks. Is this the sound of failing bearings or gears screaming for grease?

The bike is still under warranty so I don’t want to crack the casing unless I have to.


 

batmick1

Active Member
I have yet to see a Bosch run out of grease yet. Sounds like warranty time to me. If you get no joy, just send it to us at Performance Line Bearings we will soon have it running like new again 👍
Thanks! I do have you bookmarked.
I feel confident to install the full kit you sell myself too, if I need to.

I'll take it to my LBS first to see if they can talk Bosch into replacing it. Just wasn't sure if this is the sound that indicates bad bearings or bad gears.
 
Thanks! I do have you bookmarked.
I feel confident to install the full kit you sell myself too, if I need to.

I'll take it to my LBS first to see if they can talk Bosch into replacing it. Just wasn't sure if this is the sound that indicates bad bearings or bad gears.
It sounds like more of a whine than a deeper grumble? Personally, I would say it sounds gear related, but gear noise/failure is very unusual? I normally only see it when the motor is full of dirt or something has broken, but your motor does not sound loud enough for something to be physically broken, and your bearings are not bad enough for the motor to be full of dirt? Unfortunately, as I am sure your aware, it's always a bit tricky when listening to phone audio. Good luck with your LBS, I hope they look after you 👍
 

batmick1

Active Member
It sounds like more of a whine than a deeper grumble? Personally, I would say it sounds gear related, but gear noise/failure is very unusual? I normally only see it when the motor is full of dirt or something has broken, but your motor does not sound loud enough for something to be physically broken, and your bearings are not bad enough for the motor to be full of dirt? Unfortunately, as I am sure your aware, it's always a bit tricky when listening to phone audio. Good luck with your LBS, I hope they look after you 👍
Thanks!

There are two components to the sound. The overall level increased significantly, starting last Monday. When you used to hear just a little bit of the motor activity, now you can hear it from 10 feet away. On top of that, at low to medium load, there is a pulsed whine at about 5-10Hz, sort of dzi-dzi-dzi-dzi-dzi.... Because of the wind sound on the phone recording it doesn't come out so well but it is very annoying.
And in my experience, any sudden changes or increases in noise from any machinery are usually not a good sign.

I'll update after I have taken it to the shop. Problem is that I ride this to work every day and the shop's hours match my time in the office. I may have to take a half day off or do a work from home day.
 
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Thanks!

There are two components to the sound. The overall level increased significantly, starting last Monday. When you used to hear just a little bit of the motor activity, now you can hear it from 10 feet away. On top of that, at low to medium load, the is a pulsed whine at about 5-10Hz, sort of dzi-dzi-dzi-dzi-dzi.... Because of the wind sound on the phone recording it doesn't come out so well but it is very annoying.
And in my experience, any sudden changes or increases in noise from any machinery are usually not a good sign.

I'll update after I have taken it to the shop. Problem is that I ride this to work every day and the shop's hours match my time in the office. I may have to take a half day off or do a work from home day.
If this happened suddenly, then it maybe the crankshaft gear circlip has snapped. This is quite common and allows the crankshaft gear to rub the transfer gear cradle or one of the transfer gears, depending. This gives a high pitched whirring sound that can alter with pedal/motor load. Have you suffered a pedal strike recently?
 

batmick1

Active Member
If this happened suddenly, then it maybe the crankshaft gear circlip has snapped. This is quite common and allows the crankshaft gear to rub the transfer gear cradle or one of the transfer gears, depending. This gives a high pitched whirring sound that can alter with pedal/motor load. Have you suffered a pedal strike recently?
I did not. But if that is one of the circlips that can be seen from the outside, after removing the cranks, I'll take a look.
 

batmick1

Active Member
Update: Had the LBS take a look and hook it up to the Bosch diagnostics center. No error codes, as expected. Shop agrees that the noise is not normal and will file a warranty claim for me. Let's see what Bosch says.