City bike build questions

[snorkelgnu]

Hi!

This will be my first e-bike build, and I'm looking to add some hill-climbing assist to my city bike. I like pedaling, but I would like to commute and climb at least some of San Francisco's hills without breaking a sweat.

Some basic requirements:
Desired max speed on level ground: 32 kph
Average round trip commute: 5 km
Wheel size: 700c
Base bike: 14kg steel bike with belt drive and Shimano Alfine IGH, picture below
Brake type: disc-brakes
Rider weight: 100kg including load
Riding style: I like to pedal, just not as hard.
Terrain: mostly flat, but a few blocks of 12%-18% grade on my daily commute.
Weight: Would like to keep weight to a minimum as I occasionally carry it up stairs at train stations.
Aesthetics: It's a sharp-looking bike, and I'd like to keep the build discrete.
Budget: ~$600



I've been lurking on this forum for a while, and I think the following seems sensible:

1) Q100H front hub motor (201 RPM)

2) BMS 36V 11.6Ah bottle battery with integrated S06S sine wave controller
https://bmsbattery.com/ebike-battery/675-36v116ah-bottle-ebike-panasonic-battery-battery.html#/27-ac_voltage-200264vac/323-controller-s06s_hall_sensor_sine_wave

3) PAS sensor
https://bmsbattery.com/pas/837-dual-hall-sensor-d12-signals-easy-installation-pas.html

4) Torque arms

Questions:
1) Is the Q100H enough for hill-assist on these slopes and load, or would a Q128 and/or 48v battery be a better choice?
2) I would prefer to keep my current front wheel and tire. Any issues with rebuilding the wheel with the hub motor and heavier gauge spokes? Would 13G spokes be sufficient for a 32 spoke wheel with this motor?
3) Do I need a brake switch?
4) Because I am assembling this piecemeal, what types of cables and connectors are needed?
5) How well does the PAS work vs. torque sensor?
6) Do I need to have an LCD to set the pedal assist level? Can I use a throttle to switch this?
7) Any recommendations for integrated lights that can run off the main battery?

Any answers, suggestions, or alternative build configurations would be appreciated

 

[docw009]

If you can find 32 hole motors then you can re-use your old rim. I didn't think the Q100 or Q128 came with 32 holes though, Only 36? For spokes, I like double butted spokes like the Saphim Strong which are 13G at both ends and 14G in the middle. Gives a nice "twang" when in tension! I

You will be under $500 with the battery/motor shipped. Add $50 for rim/spokes. For display, I prefer the LCD-3, but I do have the LCD-1 on my wife's bike and it's fine and less obtrusive. No experience with their LED unit. Probably OK if controller is set up for it, but I wonder how you do that.

You also need PAS sensor, and should get the throttle and ebrake levers. The last three items, and maybe the displays, might not have connectors that fit the integrated controller. Ask them to quote a package that includes these parts with compatible connectors, unless you like the smell of rosin core solder in the morning.

I have no hills, so in doubt I would get the Q128H. I haven't put my Q128H in a frame yet. I have the Q100H in a 20" wheel. Fine for flat lands.

 

[ScooterMan101]

12-18 % grades , especially for a block or two where you do not have allot of speed before hitting the grade is really pushing the limit of the Q100 , even the 201 Rpm one, I have one .
If you go up them now at a speed of around 12 mph with just your legs then it can be done without overheating the motor. Just know with such a small motor you will still have to work very hard on those grades.

The Q100 can be bought with a 32 hole flange on the hub,
But
I am not sure the Q128 can.
Best to e-mail the vendor and find out. You want to specify 32 hole as well in the notes section when ordering a motor since shipping is so costly.

Grin Technologies has allot of experience with hub motors and using them on the front, there are hills in/near Vancouver BC so have done what you want to do , they could set you up properly when you tell where and how and what you will be riding.
They have some small motors as well, and the best or near best customer service to get you something that will work well.

 

[markz]

Go with a bigger motor, MAC from EM3EV.com

 

[ScooterMan101]

If you do get a Mac motor, because of the hills get a 10t or 12t version . ( more torque to go up the hills )

On a 700c wheel the 12 t will be better for going up hills.

 

[snorkelgnu]

Thanks for the tips. I'm going to look into a bigger motor and/or higher voltage battery and stronger controller.