I received a question about what my goals are for this upgrade, so I thought I'd summarize the journey and consider that more carefully.
I originally built this ebike (in this thread), my first, with a 9C 9x7 as recommended by ES for commuting to work. Learned a lot about gear clusters, shifting, torque arms, controllers, etc. I was going to use Headways, bought a bunch, but the bulk, weight and mounting problems caused me to try Lipo. I started with 12S 44V 5AH Turnigy for testing. Torque was marginal, with good pedaling it did the hills sort of okay. So I ordered a 9C 6x10 and upped the Lipo to 18S 66V 10AH to improve it.
Torque was possibly better with essentially the same controller and the higher voltage. Not a lot, but we understand that a lot better now with more motor knowledge. It probably wasn't a great change to make, and cost quite a bit for a debatable improvement.
I considered adding front wheel drive then, even before my first commute.
I put the other 9C 9x7 on a steel mountain bike for my son, he has used it a lot with a 10S 20AH lipo I built for it. He rides WOT so I'm glad it doesn't go too crazy fast at 10S. That has been a good solid commuter and he uses it quite a bit.
Then I went on the ES group ride to Marin, up steep hills and dirt roads. I fell a couple of times due to insufficient traction and torque and rough terrain and minimal skill and just about melted the motor. The bike worked okay for commuting, with hard pedaling on the steep hills. The ride was a bit rough at commute speeds on poor pavement.
I bought one of the new HT motors for a rear DD upgrade on the mountain bike for better climbing, then saw the Cromotor and decided a whole new bike was prudent, so I sold the HT unused.
When I built the CroBorg, the commute became a lot easier, and the mountain bike was ignored.
I wanted to try AWD on the mountain bike early on, but complications with the alloy suspension front forks and the lure of other projects tore me away from that and I never got back to it. Till now, 4 years later.
So now I have this 9C 6x10 mountain bike sitting there with lots of pedal gears but not enough torque or traction for steep hills. I have a bunch of dirt roads around here that I can't take the Croborg on that I might be able to take the mountain bike on if it had more torque. Though they may not allow electric bikes on some of them so it might not end up being a great use-case. It needs to be somewhat electrically subtle. If it looks like a regular mountain bike there are also some bike trails around the bay that may be accessible. For that it would not need the front motor, just needs to be fully pedalable. I could even swap out the front wheel if it isn't too hard.
I've been considering a fat-tire bike since before they were popular (Surly Pugsley), but that is a whole new project, and they aren't all that fun to pedal motorless so would not be good for some of the uses. Still interesting, but what to do with this existing bike, to avoid throwing away a really excellent rear wheel build. Could get a mid-drive, but that would toss the nice motor wheel, and mid-drives tend to be noisy and wear the gear train quickly. Perhaps not the most subtle setup either.
So upgrading the front wheel has again become interesting to consider. I don't want to put a heavy DD motor in the front, a light gearmotor seems like a much better choice. Balancing the power between rear and front is an interesting challenge. And one that might have value beyond my own ride. But not too hard to do.
If I repackage the battery and cover things up I can make the bike look less electric. The rear hub hides behind the cogs and brake disc, the front smaller hub will also mostly hide behind the brake disc.
But I probably will have to get new front fork. The present inexpensive suspension front fork is not good material for a gearmotor. I see good a steel fork is not too expensive, but it will make the ride more harsh. The Schwalbe Big Apples and Thudbuster will have to handle the rest.
So, at the end of the day, it doesn't need to be a commuter (I'm retiring in a few weeks), it doesn't need to be a long haul machine, I have the recumbent for that. It has a sturdy rack, and I might get a trailer for it that would make it a good grocery getter. It would be good to take camping, though a folder would be easier to manage (another ebike on my todo list, but that's a separate story). The front motor's already ordered, so we're on a trajectory.
So what is this AWD Mountain Ebike for, in no particular order?
- Better traction and torque for steep paved and dirt rides
- A medium hauler with sturdy rack and good towing capability (I don't have a cargo bike, another on my list...)
- An interesting experiment to test some AWD control ideas on
- A project to keep the old ebike from gathering dust