Chain skipping

[Dieter24]

Hi everyone

I`m hoping someone can give me some advice about a problem I am having with my cube electric bike. I changed the original derailleur system to a Rohloff gear hub and (not for the first time) I have a problem with the chain skipping after installing a new one. See the video to see the problem: https://youtu.be/t92-6N5jpTQ

This skipping or slipping of the chain doesn`t really happen much when I cycle without electric support but it very quickly becomes unbearable when I cycle at higher support modes or put a lot a pressure on the paddles when I cycle uphill or speed up from a stand still.
I asked the bike shop who installed the Rohollf hub for advice and he told me to replace the sprockets (both front and back) every time I change my chain. However, the sprockets seem more or less fine to me. Also, I’ve had this problem before shortly after replacing the sprockets. I then managed to fix it by putting on another chain which also had a problem a little at first but it disappeared after riding the bike for a bit. The chain I just took off didn`t have this problem. Since replacing all the sprocket every time I change my chain is also a bit time and money intensive I would like some more opinions on what exactly is going on here.

So it`s a Cube Cross Hybrid Pro 625 Allroud (2021 model), with a Roholff Gear Hub, a TA single chainring  (130 MM BCD, 42 tooth) front sprocket, a 17 tooth read sprocket and a Shimano CN-HG93 chain.

Any advice is much appreciated

[Matt2matt2002]

Wow. I've never heard of ring and sprocket changes with the chain!!
That's crazy.
Some folks flip the 2 rings at intervals.
Look for shark teeth shapes. Kinda curves on the ends of the teeth. That's a no no.

Someone will be along with better experience than me
Hold fast.

Matt

[Dieter24]

Thanks for the reply, small correction. He advised me to always change the rear sprocket when changing the chain and the front with signs of wear. Still think that`s a bit often though since the chains don`t normally last me that long.

But yeah like i said, the sprockets seems more or less fine to me and i`m pretty sure i`ve also had this issue when the sprockets were still pretty new.

[PH]

Wow. I've never heard of ring and sprocket changes with the chain!!
That's crazy.

That's what I do, it's what's recommended in some of the Thorn literature.  Of course if you buy reversible sprockets and chainrings then flipping them is the same as replacing. 
Looks to me like a worn chainring, the chain is non meshing properly, it's being dragged round further than the release point at the bottom and when the tension means it can't drag higher it's releasing with a jerk.  This is sometimes referred to as chain-suck, though that has several possible causes. 
Long term there's two options, keep changing chains before they wear the sprocket and chainring, there's no way of knowing when to do this other than frequent measuring.  Or, let them all wear together and replace/flip the rings when all three are worn.  I do the latter, though the tensioner might tip the balance as you'll also be wearing the pulleys. 

[martinf]

Mid motor drive means more force on the transmission, so the chain will wear more quickly than on a non-assisted bike

It might be worth investing in a stronger chain next time.

KMC do a model in 1/8" width, if using the specific KMC rear sprocket and chainring they claim much longer chain life.

Another method is to measure the chain frequently, change it when it gets to the moderate wear mark on the chain length tool (0,75% ?) an keep using cheap chains.

[energyman]

On my belted Rohloff E-Bikes there is a "snubber" on the back to stop the belt lifting on the rear cog when under pressure.  [Not that I ever go that far ]

[Dieter24]

Thanks for the replies, guess i will install a new chainring then