Advice for a first build

[AviatorTrainman]

Hey all, first time posting. I've been haunting the forums here for a while now, and gathering a lot of info, so I think I know what I'm talking about, but maybe not.

Anyways. I have a beautiful Trek FX 2 that I got in the fall to replace my 7200 that got totalled when I got struck by a car. I was at my local bike shop a while ago, and I got to test ride a 350 watt Bosch mid drive hybrid, and I loved the feel of it. More recently, I made a trip to a dedicated ebike shop, and realized that a hub motor is also a viable option. (I had previously been considering a TSDZ2 mid drive.) So now, I've been looking for a geared hub, preferably in the front (for weight balance and AWD), that could manage a top speed of around 30 km/h with pedalling. (I am a strong cyclist to begin with.) I first looked at a Bafang SWXK, then a Q85, then a SWXU, then a Q100, all because of their light weight. If I bought a Q100 24 volt kit (https://www.greenbikekit.com/24v-250w-gbk-100f-electric-bike-motor-kit.html) and got a new controller (https://www.greenbikekit.com/e-bike-brushless-high-speed-controller-350w-36v-48v-compatible.html), and used it with a 36 volt battery, would it get done what I want it to?

I weigh 60 kg, and I would like to have a light bike with a decent top speed (30 to 35 km/h), maybe a 10 Ah battery, maybe made with these cells (https://www.ev-power.eu/Li-Ion-1865...R18650.html?listtype=search&searchparam=18650) in a 4p configuration, and ability to provide a medium assist, but not be a motorbike with pedals. My questions are as follows:

1. Would this setup be too much for the motor, or will it take it like a champ? I've heard both about this motor, so I wanted to confirm.
2. Would this get me the speed I want in a 700c rim? I had assumed that since it is 201 rpm (26.5 km/h) no load speed at 24 volts, it would be a no load speed of 302 rpm (39.8 km/h) at 36 volts and 402 rpm (53! km/h) at 48 volts. Am I correct? How can I convert from no load speed to loaded? I also heard somewhere that these motors actually spin at 230 rpm, not 201.
3. Would the LCD from the kit's controller be compatible with the new dual voltage controller? Would there be some sort of connection/voltage incompatibility?
4. Would 2 torque arms do the trick on a front aluminum fork?

PS:
Thanks for reading, sorry for the wall of text/brackets.

 

[Raisedeyebrows]

One thing-I've read quite a few different threads here where people recommend against mounting a front hub motor in aluminum forks due to possible failure caused by the forces a motor puts on a set of forks. Reading that made me think putting one in a beefy steel fork like a Surly or something like that was the way to go over a cast aluminum fork.

 

[amberwolf]

If you mount it correctly, and use properly-mounted torque arms, it wont' really matter what kind of fork you have; it'll be fine at the power levels the OP is after.

Without torque arms, even a good steel fork can be damaged by the torque of even a small motor, as the dropouts are not designed on any of them to resist torque--they're only there to keep the axle in place, not to stop it from turning.

There's at least dozens of discussions about torque arms vs dropouts, and threads about various types of torque arms, with pictures, etc.

 

[amberwolf]

1. Would this setup be too much for the motor, or will it take it like a champ? I've heard both about this motor, so I wanted to confirm.

If you mean, will the motor overheat, that will depend on the continous power you put thru it vs the continous power it's designed to handle. You can see if the motor you're after is on the http://ebikes.ca/simulator and experiment with setups to see what happens under teh conditions you expect.

2. Would this get me the speed I want in a 700c rim? I had assumed that since it is 201 rpm (26.5 km/h) no load speed at 24 volts, it would be a no load speed of 302 rpm (39.8 km/h) at 36 volts and 402 rpm (53! km/h) at 48 volts. Am I correct? How can I convert from no load speed to loaded? I also heard somewhere that these motors actually spin at 230 rpm, not 201.

Loaded is usually around 75-80% of no-load speed for a given input.

As for which RPM the motor is, there are different windings of many motors, and which one it is determines it's RPM. Some vendors (like BMS Battery) don't always even send you the version you order, so you'll need to test it when you get it to see which one it actually is.

3. Would the LCD from the kit's controller be compatible with the new dual voltage controller? Would there be some sort of connection/voltage incompatibility?

LCDs are generally only compatible with the same manufacturer (and possibly model) of controller. So if the new controller is a different brand or series than the original, it may not work. Or it might display something, but not necessarily access all the same functions with one controller vs teh other.

Wiring / connectors can be different even within a brand, much less different ones.