Dual Chainring

[whiteturbo]

After anotherkiwi telling me about the glove he keeps in his panniers to change chainrings, i decided that was the way to go. So ordered a spider for the BBS01, got the 104 bcd four hole one, a 32t narrow wide raceface that i got cheap(£20) and a 42t narrow wide from China. I don't know if i have this right but i presume i put the chainrings either side of the spider, dont know if i need spacers or anything but will work it out when they all arrive(end Aug beginning Sept).
I decided to go with the narrow wide because i had to refit the front derailleur as a guide because the chain came off the chainring every time i dropped into the lowest gear and i'm praying that the narrow wide chainring will cure that, if it doesn't then i have wasted all my money.
I was originally thinking of using ordinary chainrings 130 bcd 5 hole and using my original front derailleur to change gears but as anotherkiwi said you need a long reach derailleur so i thought narrow wide to keep chain in place and a rubber glove in pannier to move the chain over when you come to a steep hill and where i live(Bristol) seems to be full of them.
Has anyone used narrow wides on ebikes and any comments on the above, especially if i have forgotten anything, advice particularly welcome.

 

[anotherkiwi]

You will also need chainring bolts. If you mount two chainrings you use the normal length ones and if you mount one chainring you need the short version.

It works for me because my climbs are measured in kilometers <- plural. The short ones I can handle on the 42 ring, short being under 4 km. The mountain pass ones are often about 6 to 9 km long so it is worth stopping and changing down. If I was in up and down territory I would definitely mount a long reach derailleur.

I chose steel chainrings for longer life with the added power of the mid-drive. I know some people get by with hardened aluminium narrow/wide chainrings but are they doing as many km? I am thinking of mounting a 38 narrow/wide when my biking needs change - that bike being used for towing and an 11 km hilly commute as well as round town riding. Long range and touring being done on something else with a triple chainring and a hub motor.

My chain has come off the chainring twice (in 1700+ km), both times off the big and onto the small while changing gear on a bumpy section of road.