|Moped [drum brake] hub with motor sprocket|
and human powered freewheel
There is no hub motor that will drive 600 to 700 lbs up a long 10% grade. But It takes a lot less power with a large gear reduction. However If you want to try to maintain a high rpm with a low slow gear, use a higher voltage [and a larger Ah battery] 16 in series is a 60volt pack. But 20cells in series = 72volts [nominal] would be even better.
I simulated several hub-motors at 1300watts with correct gear reduction for climbing a 9% grade with 450lbs, (using a smaller wheel to simulate a gear reduction) to lower the amount of stress as much as possible. I got 46 to 51 lbs thrust (about 62- 69Nm). But climbing a steeper hill could produce up to 92lbs thrust (124 Newton-meters) on 20% grade.
Don't think that spending a lot of money on a light weight, high-tech bicycle sprockets like the computer designed chain and sprockets, it is not going to help much. 1/8th inch wide sprockets and chain will make a much stronger drive-train. But a #41 chain and sprocket will out last any bicycle equipment no matter how expensive it is.
Two gears would be much better than one. But that would require a single chain that can shift. If you can find a way to have the Shimano cassette spline cut into the center of a BMX chain-wheel, you should do that. BMX chain-wheels are typically made for 1/8" chains, and are available up to 10mm thick at the center hole. The hard part is going to be finding somebody who has the very expensive single-purpose cutting tool (spline broach) that allows a machinist to put the correct splines in a round hole.
Calculating a workable top speed for the cyclone motor below
|left side drive fewer sprockets needed.|
|this kind takes very little tightening|
Wipperman Connex 7R8. It's a 3/32" BUSHING-type chain, May be high priced for a good reason: Wipperman appears to be the only manufacturer that is producing a 3/32" bushing chain anymore; probably because the buying public is used to the availability of "bushingless" chains, which shift better on a derailleur drivetrain, and are WAY cheaper to manufacture. A bushing-type chain will GREATLY extend your drivetrain life, since load is distributed over far more surface area. The 7R8 is single-chainline specific, so there is absolute minimal lateral play. Just make sure your chainline is DEAD straight.
Single speed chains, not for shifting:
The KMC Z chains (with an H in the model number) also come in both sizes rate at 2640 ft-lbs Z510HX Wide 1/8” and Z610HX Narrow 3/32” or Z1HX Narrow 3/32” heavy duty chains.
Most mechanics agree that you should replace your chain about every 2,000 to 3,000 miles so if you can build or buy a full coverage chain guard then convert to a belt drive you may possibly have a truly long lasting drive-train. 3Dprinted belt drive pulley?
It is no wonder that people would rather use a hub motor, even if it does use much more battery power. I recommend a 2500watt 5:1 geared hub motor!!! Even if you need to strengthen your frame some how.
8 Speed Cassette 11-42T
this is not good for a Mid-drive,
the sprockets bent and destroyed my derailleur
|I don't think this will work with a large sprocket|
The only way to keep your chain clean