When in 12 gear (smallest sprocket) and when in trail or turbo whilst also putting my own max power down the chain sometimes skips a few teeth.

[Gary]

Here's the code for the parts you require
Y1X498020 Sprocket Wheel 10T B & 12T D

Shimano spare parts and codes can be found here

Manuals & Technical Documents

 

[BadgerHun7er]

Order it as a spare part through any authorised Shimano dealer/Service centre

When your smallest sprockets wear past a certain point it stands to reason they will no longer be useable with a new chain. so at that point STOP trying to run new chains on it.

Personally in your situation I'd just ditch 12 speed altogether, fit a more suitable gearing range for the riding you do then let it all wear together instead of swapping/rotating chains. But look after it better. incl always shifting as smoothly as you can (By simply doing this I get 10 to 20 times the mileage you do out of your cassettes)

The strange thing is that there is no noticable wear on the sproket. Put it side to side or back to back against a brand new one and they look the same. (we are not talking about badly worn spiked teeth here, its just that the chain slips but doesn't with a new sprocket) I will try a Shimano dealer but they don't tend to stock 12 speed usually and looking on the Shimano website it isn't a stand alone product. So this is why I was asking if anyone had been able to get one and where from.

 

[Gary]

that's not strange at all. it doesn't take a lot of wear to cause new chain to slip under load on a tiny 10 or 12t sprocket. Certainly not enough to be easily noticable from just looking.

No. of course shops won't "stock" the part. It's a replacement part/spare. that's why I gave you the product code and said to order it.
They're out of stock with Madison and due back in stock in August with the UK Shimano distributor so you'll need to back order through a shop.

Meanwhile increase your cadence

 

[RebornRider]

65?!?! My average cadence over my 21 mile regular ride (that includes ~2000 feet of overall elevation gain per Garmin). is over 80. That's the blessing/curse of having dwarf legs (see profile pic ). I can make some power, but only at high revs. Maybe my username should be Wankle?

 

[bsquared]

Could be one of your motor mounts is slightly lose. I had a similar issue and that was the culprit.

 

[zerofunds]

My bike is brand new and it has done it 3 times, I was going for PBs on strava so didn't stop to see what the problem was, just changed up a few gears in a hurry to get going again. The motor would cut out and go in to limb mode.
I need to do some more testing and come to a complete stop next time it happens to see if I dropped a chain. The derailleur and indexing are perfect on the bike stand.