sproket 11 and 13 wear fast in e-onesixty 2020

[OJMad]

Hello

I have an e-onesixty 8000 2020.
Until now I have driven ca 900km.
After ca 400km the chain started to jump on the 10-and the 13-teeth-sproket when pushing hard.
As I had a litte accident causing my rear derallieur to rip the cage I thought, that might have caused the spoket to have a little damage.
So I changed both of them and everything worked well again.
Shortly afterwards, the same thing happened on my wifes e-onesixty 8000 with the 10-teeth sproket
Now, after further 500km this starts happening again.
Does anyone alse have this issue with the 2020 model?
Is there something wrong with the chainline?

 

[Gary]

it happens on the smaller sprockets for a number of reasons.

1. you will be using the 11 and 13t sprockets far more than you would on a mountain bike with no motor.
2. The less teeth a sprocket has the quicker it will wear.
3. chain wrap on an 11 and 13 tooth sprocket is tiny, so any wear (to chain or sprocket teeth) causes chain slip far sooner than with larger sprockets with much greater tooth engagement
4. Because of the clearance required for a derrailleur to operate over a wide range cassette (11-46 and above) your derailleur's top jockey wheel has to be placed lower (further from the small sprockets) creating even less chain wrap than you'd get from a traditional mech and 11-28 cassette.

On my EMTB I use (10 speed) 11-36 cassettes off road and 11-25 for commuting to increase chain wrap in the smaller sprockets and increase my cassette lifespan (especially with the commuting cassette's 1 tooth jumps spreading wear/load).

With the higher average speeds a motor allows, Ideally an EMTB cassette should be spaced differently to an mtb cassette and preferably have closer ratio spacing at the small end to spread the wear more evenly
eg. 11,12,13,15,17,19,23,27,32,36,42

Wider ratio cassettes all have a 2 tooth jump in the smallest sprockets IMO are a pretty stupid choice for an Emtb. And any cassette with a 10t smallest sprocket even more so.

 

[Gary]

Is there something wrong with the chainline?

No

 

[OJMad]

Thanks for your answer.
But i can not believe that this answer for that issue after 500km.

 

[Gary]

So what do you believe then?

 

[OJMad]

OK.So what do you believe then is such an obvious move.
I dont know what it is, but I dont blevieve in your explenation.
I am riding MTB and Racebike since 26 years and cant belive this excessive wear fo a sproket fo the reasons you mentioned.
500km. This is a MTB. so those 2 steel-sprokets might have 100km max at each. The chain shows no signs of wear yet.(not even close to.75)
So there is no lengthenig the chain or widening the gaps between the teeth, but maybe a radial wear ?
500km? I had cassettes on Racebikes lasting 7000 and more - same on MTB. That cant be explained by bigger jokeywheels, chainwraps and bigger gaps.
I can't believie I would not have heared of sprokets wearing after that shot mileage on e-bikes.

 

[Gary]

You'd have barely ever used a 10t sprocket on a normal mtb and whenever you did it would have been while spinning a fairly high cadence at low torque (and probably only ever when riding fast un technical downhill) so would never have been under the same high load torque your Emtb can be.

Go and take a look at how much chain wrap that stupid 10t sprocket actually has.
You're essentially pulling a 50lb bike under high load on just 5 teeth.
Of course that's going to slip with wear. And of course it's going to be more worn after 500km on an Emtb than an mtb. your chain did not slip when new and it does now after 500km. and it stopped slipping when you replavced the two sprockets. This isn't rocket science. Your sprockets were worn!

If you really don't believe what I'm telling you, go to your bike and wind out your B tension screw so that it creates the absolute MAX chain wrap on the smallest (10 and 12t) sprockets and I'll bet you'll find the bike no longer slips so badly in those two sprockets. You won't be able to use the larger sprockets set-up like that though. (but you would with a much closer ratio less wide range cassette)

Shifting under load and poor chain care are two other reasons Emtb noobs go through cassettes/chains more frequently.

 

[OJMad]

well, OK.
But if it is chainwrap, how come it works with no issues at all when i have new sprokets.And i already wrote that the chain is not worn yet. never had such issues with my Sram Eagle GX cassette which i use with my third chain after now 4000 km.
I dont say that you are wrong.But i can not believe it is normal after less than 500 km.

Shifting under load isn't something I do. When i have to it accidentally it is when going up.

 

[Gary]

*sigh *

 

[Aitrui]

It really doesn't matter what drivetrain or bike you have, " when pushing hard " with your full weight I guess, and motor power you will destroy your lower gears fast. I have a supposedly stronger Ebike drivetrain Sram Ex1, I change the smallest cogs around the same mileage as you. I'm using it to commute also, so using the smallest 3 cogs a lot.

You can clearly see the teeth deform on the cogs!

I think it's quite normal, just look at these small cogs, the amount of material in them, and power we running through them.

 

[GrandPaBrogan]

But i can not believe it is normal after less than 500 km.

You can’t compare wear rates between a manual bike and an eBike. The pedal torque exertion you feel and the actual torque that your chain and sprockets is receiving is deceptive. Even more so with the smaller gears because that’s often when the motor assist is being applied the most, covertly. Listen to Gary. ??