That front fender could work on mine, and possibly a second one (or if they come in other shapes) behind the fork. Will look into that, thanks.Looks like this project turned out rather nicely!
I do my own fenders often as not on bikes. You may be in the same boat. That pic above of the dirty, dusty fat bike shows where I normally end up: Using mtb mud guards. Then extend them out a bit with black gorilla tape folded horizontally across the front and back of the short almost-fender to extend it. The tape will last for years despite its soft-ish nature, and will maintain its shape while riding at speed. You can use a much smaller version of that grey body fender and I have found body fenders keep enormous amounts of water off both the bike and the battery.
Here is a pic of a front wheel change I just made on my Bullitt (35mm wide rim to support that 2.4" tire). I'm showing the pic cuz it uses a different style of fender that bolts to the fork crown and doesn't get in the way of tire clearance. I don't use the rear as there is zero clearance so I have sealed the 'bulkhead' behind the tire in other ways. This fender is made by SKS and they have other versions.
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None of these options will look as clean as what you had.
Get rid of that horrible front chainring as fast as you can afford to do so. Unfortunately the Lekkie rings have gone way up in price but they are still the best bet. Speaking of which, what does your chainline look like? The offset front to back? Thats a big deal for drivetrain longevity. Maybe the biggest. If its deflected it becomes a chainsaw to the drivetrain teeth and of course the chain itself isn't going to last.
Three different derailleur adjustment vids in this link, which is tee'd up a bit so you don't have to scroll much to get to them. The third one is from Park Tool. It takes the longest but its a complete tutorial to start from scratch and get everything perfect.
Assembly Day 1 got us a rolling chassis that looks like a bike. If you squint a little. Lets keep up the pace of progress here on Day 2talesontwowheels.com
I would not do a gear sensor at all. I have bikes with and without. I just do a stutter in my cadence and doing so is automatic now. Also redoing the BBSHD settings so it shuts down immediately and starts up soft are really important components to the success of that technique.
As for the offset, right now chain line is pretty straight onto the 8th gear (of 9) and it seems like I will be using 9th gear for almost all of the time. The 1st, 2nd and even 3rd are quite off, I don't go below 4th and that is only when I start. I could offset the chain ring (or any chain ring) for a totally straight line on 9th gear, though I may need to sacrifice 4th gear too for that...
Thx for the adjustment links, I will certainly look at that. Same with the motor settings, I haven't even started to dig into that yet.