Clicking/knocking sound Bosch CX Gen 4 motor

Bearing Man said:
This is absolutely classic motor bracket creak or click. This happens when the motor mounting plates are moving against the frame or motor body. The "click" is caused because the mounting plate bolts and screws are tight, but just not tight enough. This allows the aluminium motor plates to grip the bikes frame up to a certain point and then slip with a "click" or "creak". The motor basically tries to twist in the frame and this is why the noise gets more noticeable under load.
Re-torque your motor mounting bolts and screws, then try it again. Do not remove the mounting plates and grease them, this will make them quiet for about three weeks and then it will be worse than ever. If you do anything, remove the mounting plates and clean them and the mounting surfaces with a de-greaser, you want the aluminium brackets to grip, not slip.
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I'm having the same "creaks under load" issue with my Devinci e-Troy Lite SX motor that the OP reported. I'm taking your advice and have ordered two new bolts because the paint on the original ones was worn out, which I thought was weird. Since getting the bike, I was under the impression that I needed to grease them, so I did what many home mechanics do: I loaded them up with grease and tightened them to 30 Nm. Just to add what I've already done 1) changed and tighten chain ring 2) change pedals 3) new rear wheel and hub 4) new chain 5) Check all suspension bearings oh tighten crank
 
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Just found this thread after 'googling' the issue which I noticed on my brand new Lapierre Overvolt 8.7.

Im pretty sure it's the right pedal/crank. Tightened the pedal and I changed the cranks for shorter ones and still makes the same sound. I guess the motor mounting bolts will be next but don't think I have the right bits for that so might be a trip to the LBS.

Downside of ordering online I guess that I can't go back to the shop but I don't have anywhere that sells bikes around me so online was the only option as I don't drive.
 
Cratterbury said:
Just found this thread after 'googling' the issue which I noticed on my brand new Lapierre Overvolt 8.7.

Im pretty sure it's the right pedal/crank. Tightened the pedal and I changed the cranks for shorter ones and still makes the same sound. I guess the motor mounting bolts will be next but don't think I have the right bits for that so might be a trip to the LBS.

Downside of ordering online I guess that I can't go back to the shop but I don't have anywhere that sells bikes around me so online was the only option as I don't drive.
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I'm with you and have been chasing that "Tick" noise . The weird part is it just ticks once after pushing hard at this point I'm thinking its the motor
 
jayx4 said:
I'm with you and have been chasing that "Tick" noise . The weird part is it just ticks once after pushing hard at this point I'm thinking its the motor
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Ah mine is constant under load. I did notice the chainguide was very close to the chain so im hoping it was just that so I loosened it up a bit. If not then I'll try the motor bolts
 
Chasing the creak, tick or cracking noise can be a process of elimination. It can be a lengthy process to isolate the noise but that is necessary to identify a prevent any future issues.

Pete has identified one of the problems (with the Bosch Gen4) as the motor mount brackets (4) and loose bracket bolts (8). The sound is only noticeable (usually) under crank torque conditions while riding. Greasing these brackets is bad and allows slight movement to be un-heard thus causing more motor movement and eventually failure of the small bolts. A sheared bracket bolt in the motor is almost impossible to remove.

A small amount of blue-loctite for each small bolt can be used (imo) to prevent loosening. Once this has happened to your motor regular checks or service may be needed.

A loose chain ring can cause similar noises. Both noises has happened to me and requires immediate attention.
 
Just came back from my LBS and he didn't have a clue and says he couldn't replicate it even though ive now noticed it doesn't only happen under load, but also if I pedal in a low gear at high cadence to the point I can't go faster.
He checked the motor bolts, cranks and pedals and all were tight (he didn't check torque, just tightened by hand mind you).

He didn't check the chainring so that's something I'll have a look at but im sure it requires a special tool!?

Failing that im not quite sure what it could be but not what I wanted to experience on a brand new bike
 
Cratterbury said:
Ah mine is constant under load. I did notice the chainguide was very close to the chain so im hoping it was just that so I loosened it up a bit. If not then I'll try the motor bolts
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Yes mine is also under load and I changed my chainring , chainguide driving me crazy
 
Cratterbury said:
What bike is yours?
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Devinci E-troy lite with the Bosch SX Gen 4 and I've tried everything my list 1) Tighten motor bolts 30NM 2) New chain ring tighten 35 Nm 3) new pedals, 4) new rear wheel, 5) tighten cranks to 50 Nm yep 50Nm 6) tighten and checked all suspension bolts 6) Purchased new Bosch mounting bolts tighten again to 30Nm, 7) re-index Sram X01 derailleur. The last ditch is to change the Bosch sleeves. Ill let you know
 
Cool thank you. Just been to ask Google Gemini what tool i need for removing and tightening the chairing and it said a spider lock ring tool - are these standard for Bosch motors do you know and can I just get a cheap one on Amazon? Bosch ones are £40 whilst other brands are less than half that!
 
Cratterbury said:
Cool thank you. Just been to ask Google Gemini what tool i need for removing and tightening the chairing and it said a spider lock ring tool - are these standard for Bosch motors do you know and can I just get a cheap one on Amazon? Bosch ones are £40 whilst other brands are less than half that!
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If my memory serves me I purchased an off brand from Amazon and it didn't work so I went with the Parktool version, a little more money but it works. Park tool BBT 18
 
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jayx4 said:
If my memory serves me I purchased an off brand from Amazon and it didn't work so I went with the Parktool version, a little more money but it works. Park tool BBT 18
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Ah that's the one ive seen! Thanks for that I'll get it to try and try and find a matching socket/wrench
 
The bbt 18 needs a 36 mm wrench or socket.
As a side note, some of the motor mount brackets with bolts can be hidden in the frame, so without removing the motor you can't check if those are loose.
 
Eliadn said:
The bbt 18 needs a 36 mm wrench or socket.
As a side note, some of the motor mount brackets with bolts can be hidden in the frame, so without removing the motor you can't check if those are loose.
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Thank you, I'll also check these then as he didn't do that today at the bike shop - literally just checked 2 bolts each side that was accessible - basically just checked everything circled here -

1000014388.jpg
 
Cratterbury said:
Thank you, I'll also check these then as he didn't do that today at the bike shop - literally just checked 2 bolts each side that was accessible - basically just checked everything circled here -

View attachment 165929
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If that is a gen 4, then there are more motor bolts than those. Check Bearing mans answer above. I also have the creak, been waiting for delivery of torx plus bits to do it properly!
Btw, stunning gorgeous color of the bike!
 
Cratterbury said:
Thank you, I'll also check these then as he didn't do that today at the bike shop - literally just checked 2 bolts each side that was accessible - basically just checked everything circled here -

View attachment 165929
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Maybe I’m missing something or I misread. Did you check the 8 bolts that secure the brackets (4) to the motor. You must drop the motor to see these or have access to them. Not the 6 motor mount bolts.

A torques plus and a castle nut socket may be necessary.

And then a security torx to tighten the 8 bracket bolts.
 
Eliadn said:
If that is a gen 4, then there are more motor bolts than those. Check Bearing mans answer above. I also have the creak, been waiting for delivery of torx plus bits to do it properly!
Btw, stunning gorgeous color of the bike!
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Thank you 😊

Loving the bike apart from this knocking sound 👌


Stihldog said:
Maybe I’m missing something or I misread. Did you check the 8 bolts that secure the brackets (4) to the motor. You must drop the motor to see these or have access to them. Not the 6 motor mount bolts.
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Hey, nah you didn't misread - these are the only bolts my bike shop guy checked. He just quickly went over them whilst I was there. I guess if I asked him to book it in to check then he would have done a more thorough job but he took it for a quick spin and says he didn't hear anything.

Once ive got the bits I need, I'll check them all myself. Just ordered a bigger torque wrench which does up to 60nm as my one only goes to 24nm. Will also need the right torx for the motor bolts
 
Cratterbury said:
Thank you 😊

Loving the bike apart from this knocking sound 👌



Hey, nah you didn't misread - these are the only bolts my bike shop guy checked. He just quickly went over them whilst I was there. I guess if I asked him to book it in to check then he would have done a more thorough job but he took it for a quick spin and says he didn't hear anything.

Once ive got the bits I need, I'll check them all myself. Just ordered a bigger torque wrench which does up to 60nm as my one only goes to 24nm. Will also need the right torx for the motor bolts
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This is not high end tools but it does the job.
image.jpg
 
Eliadn said:
Does that probike tool measure torque in CCW direction? I have only the smaller one, in the papers it said CCW accuracy +-6%.
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Yes they measure ccw and cw. I’m not sure of the accuracy though.
 
Don't know if you can hear the noise here but I tried to record it.

Took the chainguide off to eliminate that as I thought it was rubbing (im sure it does still but isn't the culprit)

However if I rock the cassette back and forth ever so little it does a similar knocking noise to what I can hear when peddling. The noise comes from the chainring area though not the cassette- it's just easier to move the drivetrain by the large cog than getting mucky hands with the chainring haha

- YouTube
 
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Cratterbury said:
… it's just easier to move the drivetrain by the large cog than getting mucky hands with the chainring haha

- YouTube
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The cassette shouldn’t rock or wabble at all. If that’s the case; worn free wheel, wrong torque, poor fit, missing or worn O ring bushings or spacers.

The chain guide on the chainring is sometimes useless. Mine broke when the cuff of my pants went thru it. I removed and never replaced it.

Removing the chain guide also reduces the overall weight of the bike by 1/2 a gram. Now I go faster. 😉
 
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So i found out i don't need to be riding the bike to be making the knocking/clicking sound. I only have to shake/rock the bike side to side holding the bars. Strangely it doesn't do it if I also hold the frame or saddle.

- YouTube
 
Eliadn said:
The bbt 18 needs a 36 mm wrench or socket.
As a side note, some of the motor mount brackets with bolts can be hidden in the frame, so without removing the motor you can't check if those are loose.
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Just to add to this. The bbt 18 is an 8 sided bolt head, so actually a typical 6 sided socket won't fit. Guess how I know this.
 
Ive found it!!!!

Its the rear triangle! The bolt was very loose! Ive no idea what the torque should be so just nipped it for now until I hear back from Lapierre

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Cratterbury said:
Ive found it!!!!

Its the rear triangle! The bolt was very loose! Ive no idea what the torque should be so just nipped it for now until I hear back from Lapierre

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.
youtube.com youtube.com
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Cool, result. Pretty sure it should be blue loctite but see what Lapierre say.
 
Shop i bought from replied saying their mechanics suggested 14-18nm with loctite as you also suggested (y)

Buzzing I've sorted it! Could have saved money on the new torque wrench, lock ring tool and socket though - £60 unnecessary spend hahaha!

Thanks all

Screenshot_20250813_152234_Outlook.jpg
 
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