motor, frame, motor controller advice needed

[witor]

Hello, I am new to the forum.

I am thinking about making an electric bike to be used for commuting and recreational rides. So far I decided to go for the following: full suspension frame (to keep ride comfortable - no mountain biking planned), 1500W hub motor. I am planning to buy a second hand bike to make it as cheap as possible. I am not in a rush.

I have the following questions:

1) Which reasonable quality bike frame would you recommend. I believe drop off rear axle is a must. I would also like disc brakes and some decent shocks. Frame should allow battery being mounted somewhere on the frame.

2) There is a ton of conversion kits on aliexpress, ebay and other websites. Which one to choose? I would like 52V capable sinusoidal, programmable controller with regen braking, active braking (when controler tries to spin motor backwards - controlled with second thumb throttle), pedal assist and throttle, switchable to road legal and unrestricted modes (like bufang mid drive kits). Do controllers with all the above features even exist?

3) If a bike has more than 7 gears on the rear axle is it still suitable for conversion?

 

[sjpt]

Almost all 1500w motors are very inefficient direct drive drive, illegal, and only good for going very fast on the flat. They tend to be temptingly cheap, but by the time they are partnered with a suitable battery not so cheap at all. I suggest you keep to a legal geared hub motor; that will be a nominal 250w, but depending on the controller able to deliver up to 700w or even more over short periods.

If you have bigger tyres and/or a good suspension seat post it probably won't be worth rear suspensions

Switchable kits aren't road legal even if switched to a road legal power when on the road. When switched you still have the downsides of the inefficient heavy direct drive motor. Regen breaking is complex on all but direct drive motors; most people say complex enough not to be worth while.

Yes, no problem with number of gears. Probably best to get a hub drive that takes cassette rather than screw on gear cluster.

 

[witor]

I definitely want to go for a hub motor, but instead of direct drive I am now leaning towards a geared hub motor to have more torque to start. Extremely high speed is not my priority. I wanted a direct drive to use regen braking and reduce wear of brakes, but I guess replacing pads in disc brakes once in a while is not a big problem. With decent hydraulic brakes I should have enough stopping power. I am not considering this:

MXUS Electric Bicycle Motor Wheel Kit, E-Bike Conversion Kit, Motor Wheel, 19R Geared Hub, 1000W, 500W - AliExpress 18

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[vfr400]

I definitely want to go for a hub motor, but instead of direct drive I am now leaning towards a geared hub motor to have more torque to start. Extremely high speed is not my priority. I wanted a direct drive to use regen braking and reduce wear of brakes, but I guess replacing pads in disc brakes once in a while is not a big problem. With decent hydraulic brakes I should have enough stopping power. I am not considering this:

MXUS Electric Bicycle Motor Wheel Kit, E-Bike Conversion Kit, Motor Wheel, 19R Geared Hub, 1000W, 500W - AliExpress 18

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

Regen braking might save your brakes a bit, but will most likely do a lot of damage to your frame. It applies a massive torque to the axle when operating, which can twist the motor out of the drop-outs. you need a custom method of holding the motor if you want to use regen.

 

[Andy-Mat]

I question the validity of the question for having Regen! Is it really worth it on an e-bike, just to save a few pennies of electricity, at the end of the day?
I myself, have never had or ridden a bike with regen active, but I can certainly understand the worry mentioned by vfr400.
Some e-bikes have problems enough just getting the normal power to the ground when accelerating, without spinning the axle and ripping out the motor wiring!
It appears to me that Regen could be possibly not be cost effective enough, when one takes into account the stresses and strains on the bike frame and especially the forks (as in this case I believe!).
With a possible illegal 1500w motor, the forks will be getting a "right bashing" one way or another.
A possible fix, to also significantly reduce power usage, would be to buy a quality legal 250w motor, and forget Regen completely!
I did find this which may be interesting for some, except that what he calls "Regen" is correctly, "Dynamic or Regenerative Braking", which of course can be used as a source of Regen power:-

Or this Guy seems to know what he is talking about and reckons it only really saves brake pads, with only a tiny amount of battery power saved. I believe him:-

regards
Andy
PS. A few more videos I found that the effectiveness of the braking, is far, far less than I even thought, needing far more distance than normal brakes it seems, plus it saved him only 3.5% of the charge or around 1 mile of range.
He says himself that the extra money for the Regen, would be far better invested in a larger battery!:-

 

[sjpt]

Regen braking might save your brakes a bit, but will most likely do a lot of damage to your frame. It applies a massive torque to the axle when operating, which can twist the motor out of the drop-outs. you need a custom method of holding the motor if you want to use regen.

Good point. I took the liberty of copying your comment (properly attributed) at

Regenerative braking - Page 2 - Cycling UK Forum

forum.cyclinguk.org