Bosch CX Failure - Early Symptoms

Trevormonty

Esteemed Pedelecer
Jul 18, 2016
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NZ
Going forward, keep water away from motor, put hose on shower mode at low pressure if you must. Never Never degrease chain on bike, degreaser and bearings don't mix. Service and regrease bearing seal regularly, every few rides if muddy conditions, you will need a spider tool to remove chainring nut.

See attached for sealkit and tool part numbers from bike discount.
View attachment Cube Stereo Hybrid 140 HPA Race 500 27.5 2016 bike parts.pdf
 
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Doomanic

Pedelecer
Dec 7, 2017
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uk
All good suggestions, thanks. I have been using a Muc Off chain cleaner but I'm going over to Putolene chain wax anyway, normal lube doesn't seem to last long. I have all the required tools to do the bearing seal.
 

soundwave

Esteemed Pedelecer
May 23, 2015
15,971
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if you get self extracting crank bolts then no need for a crank puller n 5min job to remove and clean the seal.

if my bike gets covered in mud it is all clean and lube again b4 the next ride.
 

Doomanic

Pedelecer
Dec 7, 2017
214
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uk
I use a crank puller at the moment. I suppose I should get some self extracting crank bolts. The bike got cleaned after each wet ride but I guess I didn't relube the bearing seal often enough.
 

soundwave

Esteemed Pedelecer
May 23, 2015
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i grease the bearing and the seal so to make sure no crap can even get to the bearing but it dont take much riding in the mud to get it dirty.

it should never happen again if you check it now and then esp after a muddy ride.

if eddie can ride his bike through bogs and cover it in crap and not have these problems then anyone can.;)
 

Doomanic

Pedelecer
Dec 7, 2017
214
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uk
So, I picked my bike up today. All done.

I asked if Bosch supply a PDI check sheet or recommend greasing behind the seal before first use and they said no to both... [emoji848]
They also suggested that removing a factory fitted seal could affect the warranty.
For my own piece of mind I pulled the drive side crank and popped the seal off anyway...

More grease than the original, but not exactly packed with it.
I packed it with the Bosch grease that they supply with the pack of seals. Better safe than sorry.
 

Bearing Man

Trade Member
Oct 3, 2018
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Hampshire
www.ebikemotorcentre.com
Having read all the posts on this thread and many more like them, I thought I might add a little insight as someone who strips and repairs these motors on a daily basis.

The Bosch seal for the main motor bearing does go some way to stopping water and dust entering this bearing, but you must replace the grease regularly. (How regularly will depend on the amount and type of riding you do and the way you clean your bike). Yes I agree Bosch should have sealed this motor better, but this motor was conceived for road bikes and performs fine in that environment. It was the bike manufacturers that decided it would be fun in a mountain bike. Not that I am sticking up for Bosch here.

Degreasing your chain on the bike won’t affect the main motor bearing. Most degreasants are hydrocarbon based and won’t wash silicone grease away (silicone wouldn't make a very good gasket sealant if it did). But, if you do clean your bike or degrease your chain, keep your bike upright so that the water / degreaser does not pool around the bearing.

There are two other bearings that you are forgetting about. The right-hand crank bearing is just behind the circlip that the crank arm sits against. If stiffness or stickiness of the crank is felt, it can be this bearing. You can and should also pack this area with silicone grease. You can also put a smear on the left-hand crank bearing.

Once these bearings have been protected, you can quite happily ride through bogs and streams without fear of ruining your motor. (obviously totally submerging the motor will still be a bad thing.)

Bike shops rarely have the press and equipment to undertake full bearing changes on these motors and Bosch will not sell them the bearings anyway. Yes, you can buy the main motor bearing anywhere, but you or your Bosch dealer cannot buy the crank bearings. They are a bespoke size and not available on the market. This is why we had to have them made!

As for warranty scares. There are no security seals on the right-hand side of the motor and the sealing strip is re-usable. If you are careful, I would challenge any dealer to know that anyone had been in there. It’s the same with tuning dongles, there is no cleaver electronics to tell anyone that one has ever been fitted so as long as it’s removed before going back to the dealer, there will be no problem. (Obviously, I’m not suggesting you fix your own motor outside of warranty but if there is a circumstance where you absolutely have to, it could be done.)(I'm not suggesting you fit a dongle either)

Above all, don’t be afraid of puddles and enjoy your motor! If the worst does happen and you’re out of warranty, then at least your motor can now be fixed and normally for less than the price of a new rear cassette.

https://performancelinebearings.com

There are some before and after photos below

IMG_0643.JPG
017.JPG 018.JPG
019.JPG 020.JPG

Hope this helps you all get a few more miles ;)
 

stumpy150

Esteemed Pedelecer
Oct 9, 2015
319
143
Yorkshire
We have two Bosch equipped bikes in our household...MTB and a step through for my wife...I don't use mine like a ''normal'' mtb ...ie it doesn't go bashing over logs /rocks/through streams etc, just tracks/old Railway lines etc and my wifes is for gentle bimbles along country roads and tracks...BOTH seldom get wet. Yet both BOSCH motors had to be replaced with less than 500 miles on them..Bearings failed in both..2015 Activeline and 2015 Performance line.......Both were replaced under warranty.....so far all seems ok.....Mine has apprx 2500 and wifes about 1500 miles on the clocks....

Would I buy another if it failed again? At £600 a piece...NO.
 
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soundwave

Esteemed Pedelecer
May 23, 2015
15,971
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Would I buy another if it failed again? At £600 a piece...NO.
you cant buy one unless you send your motor to the dealer first, even then you can only buy a replacement for what you have.
 

stumpy150

Esteemed Pedelecer
Oct 9, 2015
319
143
Yorkshire
weird set up...I dont have to return an out of warranty Shimano cassette in order to buy another......and I have made mention of this anomaly on many occasions in the past .............
 

Fat Rat

Esteemed Pedelecer
Jun 7, 2018
1,903
726
UK
weird set up...I dont have to return an out of warranty Shimano cassette in order to buy another......and I have made mention of this anomaly on many occasions in the past .............
Not really
Its an exchange unit
Many automotive parts are like that these days as well even in the aftermarket sector
They heavily surcharge items so you return the old unit for rebuild
Bosch do it so no old motors are around for 3rd party rebuilds
Is it wrong maybe but there far from the only makers that do it .
 

bikey850

Pedelecer
Aug 22, 2016
97
15
124
UK
Bearing Man - thank you for you videos - very helpful and explains (I think) many of the issue people have with CX motors going wrong.

I expect I will be in touch in approx 18 months when my Bosch warranty runs out! If it goes wrong in the warranty period I can undertand why Bosch just replace the entire motor as many places would not have the engineering experience you have to repair them in the dealer network.

In the meantime I will endevour to wash the bike and motor as little as possible in the hope that it helps keep the rust at bay.

Thanks again,
 
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Haibike Rider

Finding my (electric) wheels
Jul 13, 2018
7
7
59
Thank you for your words Bikey850, but like I keep saying. Don't be afraid of water! It will ruin the love you have for your bike if you go around all the puddles and try carrying it across streams etc.
Apply the grease, don't jet wash the crank and don't wash the bike or store it on it's side and you should be fine. Enjoy your bike in all conditions and if the worst does come to the worst it won't cost the earth to repair it :).
 
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Bobbish

Finding my (electric) wheels
Apr 24, 2018
24
9
68
Addingham
www.youtube.com
My bike Cube Reaction Pro is in the shop at the moment, bearing went after riding in a very heavy downpour. I had to force the crank next morning to get it to turn. Then it sounded like it was grinding.
But it gets better, they could not get the bolts out to remove the motor due to them cross threading them at the factory. So I am now getting a new motor and frame. 5 weeks now nearly. The have lent me a bike while they fix it.
I commute on my bike every day in all weathers. I hope this is not going to happen regular.
 

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