Lightweight City Hub Conversion shopping list

[enujev]

I've been getting some knee issues lately so I'm looking to add a light motor and battery to my hybrid bike for a central London commute, around 30 mins each way. The aim is to bring me up to speed (15mph) after the dozen or so lights so I can spin rather than push the pedals, and to push me up a couple of small inclines - I mostly want to pedal myself to keep fit. I also need to be able to carry a light battery away with me so I can lock the bike on the street.

I'm new to this so I'm trying to keep things simple and reasonably priced with a front hub motor. I like the weight of the G370 - not much written on it but I'm hoping it's quieter than the Q series motors. Kit should come out under 4kgs total, meaning rider and bike under 85kgs.

Have I got all the right things in my shopping basket?

Motor: Bafang G370 201 rpm. To be built into a 700c wheel by my local bike shop.
Controller: T-06S 24V/36V250W Torque Simulation Sine Wave with Julei Waterproof Connector

Brake - hydraulic brake sensor
Cable - 1-4 Cable
Display - KT-LCD4
9Pins - 9Pins Motor extend cable
Throttle - Wuxing 130X Thumb throttle
PAS - KT-D12L

36v 7ah Bottle Battery: https://www.aliexpress.com/item/4000349036449.html?spm=2114.12010612.8148356.15.74594b9auUUxVQ

Bike: http://vitusbikes.com/products/mach-3-metrea-2018/

Grateful for any pointers / advice!

 

[motomech]

FYI, I've run both a Q100C and Q100H models and on a low-powered KT sine wave controller, they were both so quiet that they couldn't be heard over the tire noise above 5 MPH. The controller has a lot to do with motor noise. But that's neither here nor there as I'm sure the Bafang is a fine motor.
The only thing I see off-hand you are missing on your list is/are torque arms. That fork is alloy, so the drop-outs aren't any stronger than a suspension fork. I run two on my frt. mounted Q100H's, but my systems are around 850 Watts, instead of your proposed 540 W. One would be fine on that kind of power, but still, TA's are cheap and if you could mount two w/out any issues, it couldn't hurt.
The only other thing I might mention is that I'm not a big fan of thumb throttles and use a left-hand, half-twist throttle that replaces the chain-ring shifter that I remove (since it doesn't get used). But I suspect you would be on PAS most of the time so it's probably NBD.

 

[motomech]

I thought of something else;
As far as I know, the only way to use a hyd. brk sensor is to buy a lever/caliper combo w/it built in, expensive.
Here is what I did;
https://endless-sphere.com/forums/viewtopic.php?f=31&t=81359&p=1230540&hilit=+tektro#p1230540
Before this, when I ran the Q100 on a KT style controller, I didn't use one at all. The hyd. brk has no prob. stopping the whl/motor in an emergency. Where the brk sensor really is needed on a mini-motor is when using a square wave controller on PAS, they tend to "run-on" for a second or two when the pedaling is halted. The sine waves don't do that at all.

 

[docw009]

About your battery choice. I own several of them. The weakness is the plastic bottle cage. It cannot support the weight of the battery and will break. I hammered out a metal U-cradle for the front on my bikes and velcro the pack both in the rear and the front.

 

[enujev]

Docw thanks for the heads up on the bottle cage! I was thinking it looked far too good to be true... it seems like bikepackers solve this issue with an ‘anything cage’ - I’ve put a Blackburn on order which looks a lot sturdier: https://www.amazon.co.uk/Blackburn-Pewter-Outpost-Road-Bottle/dp/B07PP9NVT4

Motomech thanks for the tips. I think you’re right about Q series being quiet, I think I just liked the idea of the bafang brand motor.

The hydraulic sensor was bundled up with the controller in my order, it looks like a fairly crude job: http://www.topbikekit.com/2pcs-ebike-hydraulic-brake-sensor-for-power-cut-off-with-2pins-junlei-waterproof-connector-p-697.html

I read that It’s good practice to install if you’re going to have a throttle. As you say, I might not need either, but I thought nice to have the option.

Will grab some torque arms too!

 

[LeftieBiker]

If getting started after a lot of stops is an issue, then you need either a throttle or a torque sensing system that starts with little pressure on the pedal, and no crank revolution required. The throttle would likely be safer in city riding. I first got into E-bikes because of a bad knee, and for those of us who can't exert a lot of effort on startup a throttle is a necessity. Even if you don't have physical issues it's just so much nicer not to have to push the full weight of the bike forward with the pedals after every stop. I never had the money for a bike with a torque sensor so I can only comment on throttles: I used half throttles for years and still prefer them, but a good thumb throttle will be fine as long as you don't need it for constant low speed control of the motor.

 

[john61ct]

need a torque sensing system that starts with little pressure on the pedal, and no crank revolution required

What sort of sensors IRL work like that?

 

[LeftieBiker]

need a torque sensing system that starts with little pressure on the pedal, and no crank revolution required

What sort of sensors IRL work like that?

I remember seeing the claim for some pricey systems (you just press on the pedal and the motor starts) but I have no idea how well they work. My maximum price for an E-bike was $1k until last year. Now it's $2k. I'm just fine with throttles to start off.