Looking for ebike help

[JacobMTB]

Looking for ebike help

 

[JacobMTB]

ever since I've taken my bike to the shop to get the cassette replaced the chain now moves when i pedal backwards , unsure if its anything to worry about ?

 

[Neeko DeVinchi]

Which bike is it?

 

[JacobMTB]

Specialized kenevo

 

[Neeko DeVinchi]

The 2018/2019 model or the 2020/2021 model?

 

[JacobMTB]

2019 sorry

 

[Neeko DeVinchi]

Gottya. So its rocking a Brose Mag T (Specialized 1.3 motor). From what I've read and experienced, the crank shaft is seizing on the main drive unit. You have two options.
Option 1. Back pedal the bike and if the chainring is driving the chain backward, give it a real hard back pedal to loosen it. if the crank can spin freely without engaging the chainring, consider this a short term fix. It is a tell tell sign that crud/mud has got into the crank shaft. The bearingman from Performance bearings refers to this in his latest video.
Option 2. (Which sadly is inevitable), you'll need to either get the motor serviced or replaced (subject to whether you have warranty). The good news is that the brose motors are serviceable which is why I have no intentions of buying the newer levo/kenevo. With that being said, I'll see if I can find the thread so atleast you can familiarise yourself.
Nevertheless, if option 1 works, you will be able to continue to use your Kenevo. Just no, that option 2 will need to be considered eventually.
Do not squirt WD40 or any loosening agents as it will work its way into the crankshaft which will breakdown the grease within the bearings around the crankshaft.

Bare with me as I find the thread and apologies for the lengthy post.

 

[Neeko DeVinchi]

Big Brose motor upgrade now available for older motors. - EMTB Forums

Want a stronger, reliable and more watertight Brose motor? This video shows what we're doing at Performance Line Bearings to achieve this and how we're doing it. This service is available for ALL Brose motors regardless if it's for a specialized or a Bulls etc., made in 2015 or 2020, whether...

www.emtbforums.com

Hope this helps dude. From one 2019 Kenevo owner to another ?

 

[JacobMTB]

thankyou, it was completely fine until it had the cassette and chain changed. Also if i give a hard push as you said a couple of times it doesn't pedal backwards and for some reaseon it feels tighter now then it did a couple of days ago before i had the cassette changed.

 

[JacobMTB]

the cranks are tighter ^

 

[Neeko DeVinchi]

Does the chainring rotate backwards as you back pedal?

 

[JacobMTB]

Yes

 

[Neeko DeVinchi]

Can you pedal forwards without issue? Do you hear any grinding noises when the chainring is moving forward or backwards?

 

[JacobMTB]

Nope

 

[Neeko DeVinchi]

How did bike shop thread through the chain? Did they undo the upper chain guide?

 

[JacobMTB]

i have no idea as i wasnt there

 

[Neeko DeVinchi]

Ok. Can you remove the chain? Usually most bike shops will use a new chain with quick links.

 

[JacobMTB]

yes i can remove the chain

 

[Neeko DeVinchi]

Please remove the chain off the bike completely. Once then, we'll need to assess whether the chainring is interfering with the crank. Kindly let me know once you've done this.

 

[JacobMTB]

hi I wont be able to do tonight will be able to do tomorrow

 

[Neeko DeVinchi]

That's fine. Essentially, you'll need to approach this by trial and error. The chain shouldn't rotate backwards when back pedaling. It stands to reason that something's happened when your LBS installed the chain.
Once the chain is removed, rotate the cranks forward to see if the chainring moves forward and then backwards. If you're still encountering this issue, you'll need to remove the left crank off (drive side). Its self extracting with an 8mm Allen key.
I'll explain further if you chain removed doesn't resolve the problem.

 

[JacobMTB]

ok thanks for your help

 

[Neeko DeVinchi]

Not a prob. I'll see if I can grab the attention of the Bearing Man himself as he may have some handy pointers.

 

[JacobMTB]

brilliant cheers

 

[Bearing Man]

I think you are testing in the right way but need to determine if this could be a needle roller bearing seizure, or partial sprag bearing failure. Personally, I would suspect the needle roller bearing. We see this quite often, bikes going in for work, the owner or the shop clean the bike and then leave it to sit after the work is done. The bearing seizes and crank goes stiff. To prove this theory, lay your bike on its side and spray a little freeing oil into the gap between the crank and the sprocket carrier, if the crank frees off, you’ve nailed it. Please DO NOT keep putting oil into this area. It is not a fix, the damage is already done and more oil will just cause problems elsewhere in the motor. Hope this helps.

 

[JacobMTB]

Is it possible to send a video of what its doing ?

 

[JacobMTB]

Ive sprayed some lubricant in there and it is still not ok

 

[Bearing Man]

Ive sprayed some lubricant in there and it is still not ok

But is it different? Better or worse?

 

[JacobMTB]

its better

 

[Bearing Man]

Then that bearing is the most likely suspect. Now, did you or the bike shop give the bike a good clean before the work was done?