best Bafang Mid Drive option for off-road trike? No human power input

[Amber]

Hi, I am trying to work out which mid drive option is best for my proposed Hp Velotechnik Enduro trike, use and requirements. Thank you for your help. 

 Mid drive seemed best for torque in off-road use. Although a mid-drive motor wears out other drive train components other than the chain faster, too, like the front sprocket and rear cassette. Downside is mid Drive cannot do reverse like a rear GMAC hub motor. http://www.triketech.com/Drivetrain/PowerAssist/HPV-MAC-V2.html

Questions for Bafang mid drive motor choice and trike parts-
-For my use should I get 250W, 500W or 750W? Battery options differ between them. BBS01B-ETM, 250W 36V, 100nM torque, UK road legal. BBS02 500W, 36V or 48V, around 100NM, off road only. BBS02B 750W, 48V, up to 120NM of torque, off road only.   See below for more info
- Can the bike parts cope with the amount of torque? Should I get a Rohloff speed Hub gear or use a derailleur?
-Will I have a good ratio of gears available to me for when I am well enough health wise to no longer require pedal assistance for steep long hills and can do 100% human power?
- The motor set up needs to have a pedal/cadence sensor as well as the option of a  throttle, hence the choice of Bafang over Tongsheng or Shimano Steps. 
-Need a max level of torque at low speeds  and not a high speed machine. answers below are from the respective shops

My requirements and use
For bike rides; off road on mountains, in forests, along converted railway tracks and long distance rides as well using it as a 'wheelchair' to go on hikes. There will be times I will be 100% reliant on the motor to get me up steep hills on rough ground with zero human input. Need high torque at low speeds up steep hills, not a speed machine. 
 Due to the ME/Chronic Fatigue Syndrome my effort has to remain minimal throughout my ride. I cannot put effort into pedalling before it decides to give assistance, nor can I maintain any level of effort.   I cannot have a sensor where the amount of help you get from the motor is equivalent to the amount of effort you put into pedalling.  I assume I need a cadence based pedal sensor and not a torque based one.

The Trike--
The HP Velotechnik Enduro trike, 26 inch rear wheel, 20inch front wheels.. The website says the following- Enduro: one configuration option available- Sturmey archer tripleshift 30 speed- Sturmey Archer 3-speed internal gear hub with the shimano xt 10-speed rear derailleur and cassette 11-36. Sram GX crank set (I need short cranks 155mm).  The webpage says Bottom bracket standard: BSA 68 mm.
I am 54kg or 8 1/2 stone.  Trike has a maximum of 110kg off road load capacity.


Mid drive options
Bafang BBS01B-ETM - BBS01B-ETM, 36V, 250W motor. A peak of 100nM of torque. https://www.brightonebikes.co.uk/store/p112/Bafang%C2%AE_BBS01B-ETM_36V_250W_motor_kit_%28DPC-

• 18_display%29_with_LG_MH1_cell_16Ah_downtube_battery.html
  UK road legal- Pedal assistance set to cease at 15.6 mph. 
   9 gradually increasing levels of assistance 
  These have PAS (cadence based) pedal assist with the option to install a throttle too. The power delivery of the Bafang BBSxx motors is by a cadence based PAS sensor rather than a torque sensor, meaning that the selected assist level will be maintained providing the pedals are rotated at a suitable cadence, opposed to requiring greater input through the pedals from the rider in order to receive the higher output from the motor assist.
  Battery size choice depends on a number of factors, currently I offer 'Reention Polly' 36V 16Ah (576WH) down-tube style mount batteries.
   Either decent quality derailleur gears or an IGH are fine with the motor system - careful consideration should be payed to correct gearing ratios for rider/usage/terrain.  The Bafang BBS mid-drive assist system works with a single chainring up front, so the total number of gears is the number of sprockets on the rear cassette (or gears inside an internal hub gear). - I would note that it isn't necessarily the number of gears available that's so important, but more the ratio range of the gearing i.e. 8 speed with 11-48T would arguably be better than 12 speed with 14-28T - hope that makes sense!

 
Bafang BBS02 500W  , 36V or 48V

• Waterproof GradeIP65
  This is for off road use only in the UK.
  around 100NM torque
  18 amp controller (built into drive system) with upgraded IRFB3077 mosfets (ie reliable)
  Cadence sensing, not torque sensing.
  Replacement cable brake levers with motor cutouts (Hydraulic cutout sensors optional extra)
  Bafang thumb throttle (may be used on both sides) or twist grip
  LCD Display – P850C – Full Colour44T/46T/52T chainwheel – you choose.
  Replacement cranks (both sides!)Speed Sensor and magnetAll required cables
  Additional kit required to fit to 73mm bottom bracket is supplied

https://custombuilt-ebikes.co.uk/product/bafang-bbs02-500w-mid-drive-motor-colour-screen/

Bafang BBS02B 750W, 48V

• The Bafang BBS02 is for off road use only in the UK.
   up to 120NM of torque25 amp controller (built into drive system) with upgraded IRFB3077 mosfets (ie reliable)
  Cadence sensing, not torque sensing.
  Replacement cable brake levers with motor cutouts (Hydraulic cutout sensors optional extra
  )Bafang thumb throttle (may be used on both sides) or twist grip.
  The kit gives you pedal assistance and a throttle.LCD Display – Bafang 850C – Full Colour. or 500C display
  44T/46T/52T chain wheel – make your choice.
  Replacement cranks (both sides!)
  Speed Sensor and magnet. speed sensor extension cable fit bikes with a bottom bracket of between 67mm and 73mm. 
  48V 22.5Ah downtube battery
  We strongly suggest using a gear change sensor though, and maybe even a handlebar mounted motor cutout to aid smooth gear changing. standard chain and rear derailleur mechanism is ok.

https://custombuilt-ebikes.co.uk/product/bafang-bbs02-750w-mid-drive-motor-colour-screen/

Could maybe swap some parts and use them from https://ebikes.ca if they are superior e.g.- 24 pole PAS pedal sensor. - if you have a square taped spindle with 5mm exposed spindle. https://ebikes.ca/getting-started/pas-options.html.- ligo batteries. Can be series stacked for 72V without issue.  https://ebikes.ca/product-info/grin-products/ligo-batteries.html-Grin controllers- waterproof-Phaserunner MTs and Frankenrunner MTs will have the option to connect to BBSHD mid drive systems using the following cable: https://ebikes.ca/phaserunner-bbshd-motor-harness.html

For comparison - ICE trike shimano steps EP8. 2.6kg.  250w electric motor, 85Nm torque, 630Wh battery. 36V/17.5Ah. However, Shimano steps doesn't have the option of a throttle as well as pedal assist. 

Thank you for your help

 

[E-HP]

I couldn't tell if the ability to pedal is a requirement or not. It seems like it that wasn't part of the criteria, you could focus more on reliability, simplifying and/or strengthening the drive train, possibly going to a single speed and heavier chain, etc. I noticed that there are several YouTube videos where the setups are using really low gearing for most riding (although difficult to pedal along with), and less wear and tear on the drive train. If you aren't pedaling, then you can choose one gear that keeps the motor happy and running efficiently and forget about shifting. You could still pedal as much as you want, but just not contributing. No problem starting from a stop.

https://youtu.be/Ou9pNrJx3xE?t=281

 

[biphaeboh]

I couldn't tell if the ability to pedal is a requirement or not. It seems like it that wasn't part of the criteria, you could focus more on reliability, simplifying and/or strengthening the drive train, possibly going to a single speed and heavier chain, etc. I noticed that there are several YouTube videos where the setups are using really low gearing for most riding (although difficult to pedal along with), and less wear and tear on the drive train. If you aren't pedaling, then you can choose one gear that keeps the motor happy and running efficiently and forget about shifting. You could still pedal as much as you want, but just not contributing. No problem starting from a stop.

https://youtu.be/Ou9pNrJx3xE?t=281

Oh, thats the guy in Kamloops, running the BBSHD at 72 volts, 4000 watts, with a 1:1 gear ratio, no pedalling, just throttle.
You can buy their controller kit, but the waitlist is months.
Not my cup of tea but it shows what you can get out of that motor.

 

[Mickatroid]

I think I found the trike you are talking about online. There is an awful lot of chain there to wear out as well.

A high-quality geared rear hub that supports a suitable tyre for comfort might be worth further consideration. Still some good choice in strong 26 inch rims because of downhill.

I see the real value in mid drive being for rear suspension setups to deal with the unsprung mass problem of a hub. I have ridden a dually with a big hub motor and it was a bit weird. With a recumbent the extra weight upfront for a 'mid' drive might even be a bit sketchy. Don't know.

Mid drive maybe the latest but good quality hub motors are still excellent and have their place.

 

[ccihon]

The real value of mid drive is less about rear suspension, though it helps - the ability to change gear ratios of motor/wheel is what really makes a difference. I have a recumbent bike that I have driven by a rear-hub dd motor, and now via BBSHD, though with human input, and at standard (52v) output.

For uphill or high-toque needs as are often encountered off-road, especially without pedaling, the mid drive offers gear choices via rear derrraileur, or possibly an IGH. Drawback is definitely the wear and compromise of the long chain and boom-mounted motor. If there is really no pedaling going on, it may make sense to try mounting a motor "mid-ship" as some powered recumbents do - shorting the chain considerably.

 

[PaPaSteve]

Here's a different motor direction to consider :

http://abc.eznettools.net/D300013/X300109/eKits2.html

https://www.cyclone-tw.com/product/8

These kits have been around much longer the any of the crank mounted kits like the Bafang.
I've used them in a dozen different applications with great success.
Easy to gear up for speed or gear down for hills.
They are throttle operated so pedaling is not required.
No reverse option.

Caveat ... this kit is simple for a guy like my but may require some creative solutions for batteries or ...

 

[PaPaSteve]

Cyclone has a 1680 and a 3000 motor available.
500 is the only size I've used ... most applications were with a rear derailleur but an Alpine or Nexus internal geared hub does work.
Have put them on tandems, pedal cabs, cruiser bikes, 2 wheeled recumbents and a custom build offroad quad with very low gearing.
The controller is packaged with the motor.
No display provided. I used the Cycle Analyst on a couple builds.
Batteries were smallish, low cost sealed lead acid but no reason lithium couldn't be used instead.

 

[fireflyer451]

I have an ICE Adventure trike, BBSHD, Enviolo Cargo Hub IGH, off road tires all around. This IS my 'off road' trike. The BBSHD works great in this configuration, plenty of power, never overheats. I have a TSDZ2 on another trike that is my 'street trike', and that motor works fine there, but it was not powerful enough for the steep, off-road riding. Go BBSHD.

 

[Bullfrog]

A mid drive is definitely the best type of motor for your application.

For everyone...one caution regarding the Sturmey Archer three speed hubs, stay away from any of them that have the three small humps on the hub to drive the sprocket...the little humps will round off and leave you stranded if you apply too much torque and "too much" is not very much in this case. The SA hubs that have cassette splines attached to the hub are the way to go...the "CS-RK3" SA 3 speed hub is what I am talking about.

BBSHD is the Bafang motor you want. Aftermarket support is better for the "HD" than it is for the other options as well as it being able to produce more torque than the "01" and the "02".

I have had small components inside a geared hub motor come apart due to rough riding off road and a DD motor is heavier plus it doesn't produce enough torque compared to a mid drive motor with gears.

FYI, I am running a BBSHD with a Lekkie 28t chain ring, a 22t White Industries Trials freewheel and my top speed is 18-20 mph with a 27.5x2.8" rear tire. My set up allows me to ride in the woods and climb hills without ever shifting or the motor over heating and any faster than 20 mph and I'd wrap myself around one of those trees that tend to jump out in front of me when I am riding too fast .

The Lightning Rod ebike motor/kit might be worth considering...check it out and see if it might give you more ground clearance but getting it mounted on your trike may take it out of consideration. This is a link to one of the Lightning Rod Kits: Single Stage Big Block Middrive- RHD