Bike has been running smoothly for 70 miles or so now. After looking at all of the symptoms and how the skipping developed, here's what I believe happened.
With the initial conversion, I used a new (cheap) chain and the original cassette and derailleur. No skipping with that combo for a couple hundred miles, but inability to access 1st gear due to the chain line.
Swapped the cassette to the cheap Shimano 7 speed and added a spacer to make up for the smaller stack. The first day everything ran smoothly through all gears. The second day, the chain began skipping badly.
Swapped out the cassette and derailleur and it helped slightly, but still skipped on the smaller cogs.
Swapped out the chain and helped more, but still began to skip (this was after my last post where I thought I achieved success)
Visually noticed a bit of occasional runout when viewing the largest cog while rotating the wheel, and determined there was some play.
Added an additional 0.5mm spacer and the play was gone, and bike has been running smoothly for a few longer rides, like it should.
Conclusion: The original issue was caused by running a cheap cassette and likely the need for the additional spacer to keep the cassette from moving/wobbling. The cheap cassette likely also was a factor, since it is rivetted together in some may places, it's probably not suited for ebike power, and flexing under power. The bad skipping under load ruined the chain. There was no stretching in length, but some side plates were buldging out so much they were catching the next bigger cog. Replacing the ruined chain, and the cheap cassette, after adding the additional spacer corrected all of the issues, both the original and the ones created by skipping under load.
In the end, it seems like making sure the spacers were adequate would have prevented the skipping, but the cheap cassette may have eventually caused issues due to its weak design.
With the initial conversion, I used a new (cheap) chain and the original cassette and derailleur. No skipping with that combo for a couple hundred miles, but inability to access 1st gear due to the chain line.
Swapped the cassette to the cheap Shimano 7 speed and added a spacer to make up for the smaller stack. The first day everything ran smoothly through all gears. The second day, the chain began skipping badly.
Swapped out the cassette and derailleur and it helped slightly, but still skipped on the smaller cogs.
Swapped out the chain and helped more, but still began to skip (this was after my last post where I thought I achieved success)
Visually noticed a bit of occasional runout when viewing the largest cog while rotating the wheel, and determined there was some play.
Added an additional 0.5mm spacer and the play was gone, and bike has been running smoothly for a few longer rides, like it should.
Conclusion: The original issue was caused by running a cheap cassette and likely the need for the additional spacer to keep the cassette from moving/wobbling. The cheap cassette likely also was a factor, since it is rivetted together in some may places, it's probably not suited for ebike power, and flexing under power. The bad skipping under load ruined the chain. There was no stretching in length, but some side plates were buldging out so much they were catching the next bigger cog. Replacing the ruined chain, and the cheap cassette, after adding the additional spacer corrected all of the issues, both the original and the ones created by skipping under load.
In the end, it seems like making sure the spacers were adequate would have prevented the skipping, but the cheap cassette may have eventually caused issues due to its weak design.
