Command + conquer: torque, light, silent hub motor?

[daffy99]

Hello everybody, avid reader and prospective ebike upgrade wrangler here. I am posting to get component advice and also suggestions for sourcing components.

I would like to add a hub motor to the 135 mm QR rear end of my full-suspension mountain bike, with 10-speed cassette and disc brakes:

• motor relatively light-weight, to limit moving mass in the rear, about 2.5 kg max; I am targeting a maximum total weight of the electrical kit of 5 kg (motor, battery, controller, sundries)
• primarily for torque and performance on steep inclines (not off-road) - total powered system weight after modification will probably be around 115 kg
• low level of noise and efficiency (I don't care about rated watts, this is limited by the weight ceiling anyway)
• all sensors built-in to make it easily to control
• robust, good freewheeling

From my reading, the following (one) motor choice seems to qualify

• Q128C - 201rpm @ 36 volt (sold under various other labels?), operated at (up to) 48 volt

I have excluded the Keyde motors, as the measurements indicate that they will not fit the rear triangle. Would that choice of motor make sense?

What I am totally, totally unclear about is how to command and conquer this motor.

First of all, I want the motor to add to my power output. I am able to produce about 200 Watt (sustained) myself, but at times simply don't want to sweat from the physical exercise.

I need to have PAS (to at least create an impression of road legal operations). I am under the impression that the more magnets I get, the better, for responsiveness. What is the best Octalink / Hollowtech II-compatible PAS hardware that money can buy?

I want a kickstart / launch control feature, possibly using a small thumb lever. Traffic lights - ready, steady - launch in highest gear! There goes the torque.

I want to get up steep hills with high(er) speed - basically flatten that incline. I could imagine that, again, a small thumb lever would help: push and the motor emits power. Release, I am on my own again. Benefit: reduce pedal bob into suspension.

The whole system should be very responsive - kick in quickly, stop as soon as possible, perhaps with configurable ramping up and down? Braking is hydraulic; I would be tempted to run without any cut-out sensors?

I don't care all that much about displays - the less the better, the stealthier.

What controller do I need to get this done, enabling also silent motor operations? I read about sine wave controllers. Then about the specific S12S controller. Then about the better(?) Kunteng controllers. And the supposedly fantastic Lishui controllers with programmability via Bluetooth. And Infineon components being the Real Deal. And I am lost.

I'd rather overspend on the controller (say, USD 100 instead of the usual USD 40 from China?), because I believe that this will make the difference between getting a nicely running system, where I can tweak battery and motor performance, versus something that only just works as it is. Ideally, I could also experiment with various means to operate the system - be it through the lever or the PAS.

I am well aware that I also need a battery, but hope that I can treat it as an isolated problem? After all, that's why I go upgrade - loose the concern about being locked into a proprietary battery system. I would hope then that the controller is able to optimally discharge the battery and protect it? Then I would get "some" decent enough 48 volt battery, rather smaller than larger for weight, with a BMS that protects the battery on charge?

The battery, and most everything non-motor, I would want to stuff into a triangle bag such as the Abus Basico ST 5200 (https://www.abus.com/eng/Mobile-Security/Bike-Safety-and-Security/Bags/Basico/Basico-ST-5200), unobtrusive, easily removable. The controller I could put into a separate saddle bag?

Puh. And if you made it down here - perhaps you know about sourcing options, too? I am aware of BMSbattery, pspower, elifebike, greenbikeit, em3ev. Any other sources for the motor(s) / controller / PAS you will have suggested?

Many, many thanks for having read so far - and many thanks in advance for any input you can provide!

 

[Woosh]

Hello Daffy,

the £499 woosh XF08C kit is nearly there but not quite. You get cassette fitting for your 10-speed cassette, enough instant power from the throttle for most situation.
failings: It's not 2.5kg, it's 3kg motor. No torque sensor, you will need to buy it separately. I still haven't sourced one that can do both PAS and TS and throttle but someone will come up with something soon because there is a big pent up demand for a BB torque sensor that does all that.
http://wooshbikes.co.uk/?hubkits

 

[daffy99]

the £499 woosh XF08C kit is nearly there but not quite.

Many thanks for the candid response!

I see one additional challenge: the XF08C drawing as published at http://www.mxusebikekit.com/proshow.aspx?cateid=68&productsid=195 indicates on overall motor width of at least 140 mm, with the labeling next to that saying "Open size(mm):142"

My rear triangle really has an opening width of 135 mm. I am not sure how well the joints / bearings of the full suspension system would like that strain of forcing the triangle open by 5-7 mm. On a steel frame, I would not care. On a full suspension frame made from aluminum, with all those joints and bearings?

 

[Woosh]

The drawing said 140mm, I had no problem fitting them on bikes with 135mm rear drop out.
May have to squeeze the rear triangle a little bit to drop the rear wheel in, but it's really no effort.

 

[Deleted member 4366]

Don't worry too much about the width. They can all be fitted fairly easily. 5kg all up is a bit on the low side. A Q128C must be 3.5kg on its own, so a the total kit with a down-tube battery will be around 8kg. If you want light, it has to be the Q100C or the Keyde, but neither of them are torque monsters.

As I've said before, E-bike nirvana is a Q128C at 48v with a sine wave controller around 17 to 20 amps, depending on how much torque you want. forget the S12S. It's too big. The possibilities are the 20 amp dolphin battery one sold separately by BMSB, one of the batteries with the included controllers, or one of the PSWPower ones. You can also find them on Aliexpress. All those controllers give you the control that you describe.

Shimano Hollowtech cranks are pretty good. They're light and it's easy to fit the pedal sensor on the left side. You have to open up the hole in the magnet disc to 25mm, then thin down the thicker bit in the centre to make it flat and thinner. You need a bike with a 68mm bottom bracket. 73mm is too wide to fit the sensor like that. Avoid Octalink or any similar splined bottom brackets. they're heavy and very difficult to fit the pedal sensor.

 

[daffy99]

For controllers I can find the KT36 from pswpower - http://www.pswpower.com/peng/iview.asp?KeyID=dtpic-2016-3F-33C0.50CGS (also via https://www.aliexpress.com/store/1314442) - would that work?

Not sure about bmsbattery - is this the controller you are referring to: https://bmsbattery.com/controller/698-sine-wave-controller-for-09-case-controller.html

I am trying to avoid too much integration, want to be able to keep the battery relatively "pure" for the time being.

FWIW, I am already on http://www.chainreactioncycles.com/shimano-xt-slx-bb70-hollowtech-ii-bottom-bracket/rp-prod41445 with an Octalink crankset (XT FC M770-10 at the moment, new replacement / refreshment part is on its way as SLX FC M670). Fitting a PAS there is a challenge? From the looks of it, https://www.aliexpress.com/store/product/PAS-D-12-easy-assemble-Pulse-Padel-Assistant-Sensor-for-Electric-Bicycle/1314442_32756646650.html could work?

 

[Woosh]

we supply the appropriate pedal sensor for your bike. You can select right side PAS, left side PAS or octalink/isis/hollowtech if you have one of them.