bosch gen 4 rattle, reply from bosch

[Blue Moon]

if it was a design thing, wouldn't they all do it? Mine doesn't make any rattle noise at all

My wife’s Rail 7 is on 950 miles and it’s rattle free. The chain wheel nut has come loose once which my lbs sorted straight away.

 

[PhilBaker]

I think they all do it from the reports I've read, but it’s not a rattle, more a slight sound as you go from freewheeling to engaging the motor.

If you ride along freewheeling then very slightly peddle to engage the motor, there is a slight clunk as it engages.

I didn’t notice it all all then read the reports and watched the videos and realised mine did do it but as I said, it’s only a slight clunk.

Doesn’t bother me to be honest, as long as it doesn’t lead to any failure so good to hear your a lot of Km’s in with no issues.

 

[Akiwi]

When I first got mine, the rattling was driving me crazy. HOWEVER, In my case I think it was the cables in the head of the frame rattling around. I stuffed some foam pipe insulation up there around the cables and now it is completely silent up there. It could also be because I added lights and had a loop of spare power cable up there so maybe my own doing.
As I said, riding downhill over roots / stones I don't notice it any more. maybe it's gone, maybeI just got so used to it I don't hear it anymore. I keep forgetting to purposfully listen for it when I am out enjoying myself.
Personally I love the new Gen 4 motor compared with the previous generation.

 

[Beekeeper]

I thought I’d see what Bosch said and this was their response:-


With regards to the 2020 CX motor noise, we consider this product to be our new Performance Line CX to be the most powerful drive system from Bosch.

It is optimised for sporty, powerful and dynamic riding on the trail. Along with all the positive features that make for a whole new trail experience, it is also quite audible. This is a small penalty for significantly better performance and more riding enjoyment.

Please note, among other factors, noises are acoustic vibrations generated by friction and forces. Efficient power transmission on the eBike is simply impossible without acoustic vibrations.

We would ask you to do at least 300Km on the bike to help it "retract". If you feel excessive noise persists then we would ask you to take the bike to a dealer for analysis and comparison.

We hope this helps

Best regards

Your Bosch eBike team

Dear sir / madam,
please continue to ride your bike for several hundred miles.
At some point another component unrelated to the motor will probably make an even louder noise, thus making you unaware of the motor noise.
Have a good day.

 

[MsO]

Sorted out the rattling noise now the bike won't come on take the battery out have a fiddle about put battery back in it starts then it doesn't just came back from a20 mile ride no problems now I got this problem going back to lbs tomorrow

 

[Beekeeper]

hi

Put less than 200 miles on my team cube stereo and it seems to have the rattle everyone is talking about, which has got louder over time, to a point where I don't even want to ride it sounds broke.

So I fired a few emails to Bosch
this is what they said.

The clacking and rattling noise is known and has no impact on performance, functionality and reliability.​

​

Here is an official statement from Bosch regarding this noise:​

"When riding an eBike/eMTB on rough and technical terrain downhill, vibrations of the chain/chainring often occur. Those vibrations can be transferred to the frame, the drive unit and to the inner gear wheel (inside the drive unit). In some cases when freewheeling, a metallic sound can be generated when the inner gear wheel is not under load. How much vibration and sound is transferred depends on the type of bike (for example hardtail vs full suspension and aluminum vs carbon).​

​

The current Performance Line CX is designed with high power density and thermal stability as well as a highly efficient gearing mechanism and incredibly smooth-running gears. Paired with reduced weight, lower wall thickness and improved heat release it is easier for mechanical noises to be omitted. Therefore the noise may sound a little more prominent when compared with other drives. This noise does not have any influence on the performance, functionality or reliability of the motor. Usually an eMTB also makes several other noises as it navigates these technical sections of trail (tyres gripping/skidding, chain slapping etc) and thus any noises from the motor are drowned out.​

​

On further request: We would also like to note that we continuously develop our products. This includes looking at whether this specific noise can be reduced in the current Performance Line CX."​

​

​

Best Regards​

​

Your Bosch eBike-team​

Dear sir / madam,

Thank you for your letter expressing your concerns with your new build house.

I would like to assure you that your house uses the most modern and technologically advanced materials.

We would like to point out however that the walls are thinner and lighter and you can often hear some unwanted noise from your neighbours because of this.

However, with your TV, washing machine and hoover all on at the same time, this should never be an issue.

Have a great day ??

 

[GrahamPaul]

Dear sir / madam,

Thank you for your letter expressing your concerns with your new build house.

I would like to assure you that your house uses the most modern and technologically advanced materials.

We would like to point out however that the walls are thinner and lighter and you can often hear some unwanted noise from your neighbours because of this.

However, with your TV, washing machine and hoover all on at the same time, this should never be an issue.

Have a great day ??

I rented a (reasonably new) detached house in Wokingham for a year in 2015. I can confirm the contents of your letter are indeed correct.

 

[b45her]

Just a thought.

Given the new Bosch gen 4 motor completely disengages at the speed limiter to allow resistance free peddling, is this “clunk” when going from freewheeling to pedalling the motor re-engaging?

essentially yes, its basicly a dt swiss style star ratchet on the cranks.

 

[Bearing Man]

I have looked a little more into this and the noise is not coming, as first thought, from the ratchet. I can feel the ratchet engage and then clonk! There is something else but I just don't have time to strip the motor again yet.

 

[b45her]

I have looked a little more into this and the noise is not coming, as first thought, from the ratchet. I can feel the ratchet engage and then clonk! There is something else but I just don't have time to strip the motor again yet.

nico voulioz has put rubber between the crank arm and ring on his glp 2 to quieten it down a little, my orbea wild is pretty quiet but i have heared quite noisey gen 4's

 

[PhilBaker]

I have looked a little more into this and the noise is not coming, as first thought, from the ratchet. I can feel the ratchet engage and then clonk! There is something else but I just don't have time to strip the motor again yet.

Appreciate your investigations on this one as I’m sure many others do!

 

[FLY135]

I have a Bosch Performance CX on my full suspension bike that is just over a year old. It recently developed a rattle when under load. At first I thought it was the chain rubbing against the guide, but after some adjustment to make sure that it wasn't the rattle still existed. I mainly have ridden the bike on paved trails and have taken it off road about infrequently. I doubt the bike has over 500 miles. This doesn't give me a lot of confidence in Bosch motors.

 

[Vinnykiwi]

I have looked a little more into this and the noise is not coming, as first thought, from the ratchet. I can feel the ratchet engage and then clonk! There is something else but I just don't have time to strip the motor again yet.

Hi, have you had a chance to look into this rattle? I absolutely love my GLP2 but the constant rattle does my head in... I am on my second engine, no better unfortunately. I even hear a knocking noise when pedalling hard and fast (Turbo) uphill on rough or rooty sections. Any thoughts about that? All my cables have insulation around them..

 

[The Hodge]

I'm 63 years old ..my teenage ( and beyond) drinking years were spent listening to / watching loud rock bands ...
I either don't have this rattle on the gen 4 motor ..or my ears really are too fkd to notice ?

 

[Bearing Man]

Hi, have you had a chance to look into this rattle? I absolutely love my GLP2 but the constant rattle does my head in... I am on my second engine, no better unfortunately. I even hear a knocking noise when pedalling hard and fast (Turbo) uphill on rough or rooty sections. Any thoughts about that? All my cables have insulation around them..

Sorry, not yet. Been a bit busy, but will post it when we find it.

 

[Forever Wild]

Yea at list you can get 7-8 motors changes in it's warranty period

My brose motor runs just fine. Could the high failure rate be due to the climate in which it is ridden ? Wet, muddy, rainy parts of the world ?

 

[Jamze]

Mine def rattles as per @Bearing Man 's description. Non-issue for me, you hear it when freewheeling downhill on a quiet surface like grass. It's usually drowned out by tyre noise, stones hitting the fender and frame etc. It's not a single clunk when drive disengages, it's constant when freewheeling.

 

[Bearing Man]

My brose motor runs just fine. Could the high failure rate be due to the climate in which it is ridden ? Wet, muddy, rainy parts of the world ?

We do a lot of Brose motors from California

 

[Jamze]

We do a lot of Brose motors from California

lol. I assume motors that have a rattle are ones using metal gears? Belts or nylon are quieter but possibly need more looking after? I've always assumed it was metal gears that are meshed but idling - so they rattle.

 

[Vinnykiwi]

I think the rattle is due to the Internal reduction in drag beyond the motor assist range? The ol Bosch Gen2, no rattle, the ol Shimano E8000, no rattle. Both had „excessive“ drag beyond the assist range. The new Gen4 and EP8, no drag, heaps of rattle... get my drift ?‍. I’d prefer a little more drag and much less rattle. Maybe someone will come up with an internal mod such as a shim or spring somewhere to increase tension... and drag of course.

 

[Mteam]

For the bosch gen 4 the rattle is such a non issue, I can't believe it's been made into this big thing by all the you tubers.

I simply don't notice above all the other noises a bike makes when going downhill on a rough track.

I'm guessing the ep8 is similar, but I haven't Ridden one.

 

[Vinnykiwi]

For the bosch gen 4 the rattle is such a non issue, I can't believe it's been made into this big thing by all the you tubers.

I simply don't notice above all the other noises a bike makes when going downhill on a rough track.

I'm guessing the ep8 is similar, but I haven't Ridden one.

I am not a youtuber but a downhiller who absolutely hates a loud bike. I don’t mind the sound of my tires gripping or drifting or the stones or twigs hitting the downtube. The Gen4 definitely rattles a lot not only when the going gets really rough! Well, at least on my GLP2 anyway.

 

[Mteam]

I am not a youtuber but a downhiller who absolutely hates a loud bike. I don’t mind the sound of my tires gripping or drifting or the stones or twigs hitting the downtube. The Gen4 definitely rattles a lot not only when the going gets really rough! Well, at least on my GLP2 anyway.

Could it be that some bikes accentuate the rattle more than others? Because I really don't notice it on my Orbea.

 

[Vinnykiwi]

Yes I believe so but can’t really confirm why? I have even closed off all apertures with MX foam to reduce resonance.

 

[Rob Rides EMTB]

Carbon frames definitely sound louder in my experience.

 

[Sean1.0]

I don't notice any rattle on my wife's 2020 Moustache Trail. Ally frame and Moustache have been making emtb with Bosch motors for 10 years so I expect they are pretty savvy with frame integration. Only got a few 100 miles on it so far tho.

I had a bit of rattle on an older Yamaha (Haibike allmtn) ... turned out to be cables in the downtube so an easy fix and worth checking I think.

 

[Mteam]

Carbon frames definitely sound louder in my experience.

My Orbea is carbon, I don't really notice the bosch rattle.

It did have a rattly battery cover that I thought was the bosch rattle until I worked out what it really was. A bit of stick on rubber fixed that.

 

[Vinnykiwi]

I had a bit of rattle on an older Yamaha (Haibike allmtn) ... turned out to be cables in the downtube so an easy fix and worth checking I think.
[/QUOTE]

Thanks but been there done that. Totally stripped the bike when it was still new and covered all cables / wires with that foam tubing and apertures with MX foam to ensure there is no rattling....

 

[Bearing Man]

I have a theory but I need some feedback before I strip another Gen 4 motor. Can someone try going over a peace of ground that would normally cause the rattle but without their feet on the pedals? Obviously, do not pick a piece of extreme terrain that would end in certain death without feet on pedals. Also mind your plums! ? But feedback would be helpful for workshop testing ??

 

[Vinnykiwi]

I have a theory but I need some feedback before I strip another Gen 4 motor. Can someone try going over a peace of ground that would normally cause the rattle but without their feet on the pedals? Obviously, do not pick a piece of extreme terrain that would end in certain death without feet on pedals. Also mind your plums! ? But feedback would be helpful for workshop testing ??

I will do this weekend once I tune the rebound on my rear shock a little to indeed save my plums ?. I’m gonna try to strap my phone to the bike to hear the difference, if any ?‍