Tag: e kit for trike

E-assist for a Greenspeed Anura

One of the more challenging installations I have done recently, has been the addition of a Bafang electric assist (E-assist) kit onto a Greenspeed Anura IGH.  This posed a few issues:

  • the Bafang mid-drive and the chain gobbler – used for chain tensioning –  are mutually exclusive,
  • the Anura steering rod passes exactly where the motor fits,
  • and the standard question of where to fit the display and controller!

Greenspeed Anura IGH with E-kit

If you have not been involved in fitting an e-assist kit to a recumbent, it’s easy to forget that generic kits are arranged for the standard upright bicycle, and the parts and wiring, in the main, do not just “bolt on” to a recumbent!

Back to the Anura then.  Greenspeeds’ Anura is a fine trike – much underrated in my view – offering a convenient seat height, easy on and off access, great steering, and quite surprising performance too.  Standard equipment for the IGH version is a Nuvinci 380 CVT internal gear hub and Schlumpf speed drive crank-set.

The challenges for the E-Anura are:

  1. Keeping the Nuvinci hub in the right place;
  2. Chain management (tension);
  3. Steering; and
  4. Mounting the rest of the stuff (battery, display, controller etc)

In order then…

The Nuvinci mounts in a slotted bracket that allows the hub to be moved to tension the secondary chain drive to the rear axle, and relies on the axle nuts to be very tight to stop it slipping.  This has proved problematic for some installations and riders, I added positive location devices to stop the hub axle slipping under high load.  (That’s the purple snail cam adjusters in the photo.)

Snail Cam adjuster
Snail Cam Adjuster

Chain tensioning on the IGH is essentially by the sliding of the boom used to set the frame for the riders leg length.  Workable but not ideal.  I re-routed the chain to use an over/under idler, and created a chain tensioner to look after the excess chain.

Chain tensioner for E-kit on Anura IGH
Chain Tensioner
Over/Under chain tensioner for Anura E-kit Install
The new chain management

Steering was the one thing that had to be right.  While you can fit the steering rod between the crank arms and the motor, the rod rubs the motor, bends, and restricts the steering lock available to the rider.  My solution adds a new steering arm to the fork, and runs the steering rod direct from the handlebars across the top of the motor to the fork.  Result:  play free steering with full lock available left and right!

Anura steering arm
New Steering arm

The rest of the “stuff” is more straight forward: battery mounted to the frame alongside the left rear wheel; display on a bracket on the main frame with the keypad separated and mounted on the handlebar end.

Anura E-kit battery installation
Anura E-Kit Battery Installation
E-Kit display
E-Kit Display (mounted on the boom)

 

E-Kit Controller keypad
E-Kit Controller Keypad on Handlebar

All in all, an e-assist system that preserves the trikes’ original handling.  In the words of the owners of this trike:

“…runs like a dream, Grant has been out for a few rides now and is beaming every time he rides it…”.

Nothing beats that!

Links:

DT Recumbents Electric Assist information page

E-Kit Installation on GT20

Electric assist for bicycles is a growing market, but there are limited options for the recumbent cyclist.  There are few original equipment manufacturers (OEM) fitting e-assist to trikes, and the problems with importing the batteries (and in-country support) makes the OEM fit problematic in Australia.

Essentially we are left with the do-it-yourself option, whether a dealer does it or it is truly DIY!

The choice between a hub motor (a motor built into a wheel) or mid-drive (motor built into the bottom bracket and crankset) is a bit personal, though finding a hub motor with the right width for the trike’s rear wheel spacing and gear options can be a challenge.

E-Kit driveFor this fitment, we have chosen the Bafang BBS02 mid-drive, a well known brand with a number of re-sellers in Australia.  The BBS** series are available in a range of powers, from 250 watt to over 1 kilowatt.

Talking of power, a quick word on the legals is called for.  Electric Assist bicycles in Australia are limited to 200 watt power, unless the bike complies with European directive EN15194 and is certified as complying.  (Commonly termed a Pedelec, 250 watt max.)  Queensland is further limited to 25kmh with power assistance.  This rules out any DIY kit from complying with the 250 watt requirement as the certification applies to the whole bike….

We have chosen a 350watt version, and will be de-rating it via the software options available.  Why 350 watt?  Apparently the internal wiring is somewhat heavier than the 250 watt unit.

Bafang E-kitSo what’s in a kit?

The drive unit, display/controller, e-brake levers, speed sensor, and wiring harness.  We added a gear change sensor, separate brake switches in case we wanted to keep the OEM levers, a 130mm BCD chain ring adapter, and some extension cables.  Plus a 36 volt 10 amp hour battery.

Our installation is on the popular Greenspeed GT20 Recumbent Trike.  Note this is not a factory supported option.

Fitment is straight forward. The existing bottom crankset and bracket is removed and the BBS02 installed in their place. Brake levers are replaced, and the display and controller mounted.  By far the most time was spent on mounting the controller and display, followed by tidying up the wiring.

The e-kit added approximately 8kg to the weight of the trike.

E-kit Controller

One of the beauties of the Bafang kit is the ability to configure the software, one of the downsides is the ability to configure the software….  Some of the settings are not that intuitive, and it would be possible to fry the electronics within.

In case you’re wondering, no we did not 😊.

We’ve spent some time selecting values to optimise how the boost applies, levels, how it cuts out at the speed limit, and how it cuts power when pedaling stops.

E-kit drive right view

On the road the kit works quietly away providing a smooth and steady assistance.  Some of this is because of the 200 watt limit we’ve applied, but also the software settings selected.  The motor can be more or less aggressive in its response if desired.  Note too that the BBS** series are not torque sensing – they don’t care how hard you’re pedaling, just that the pedals are turning.  Pedals turning = boost applied.

Best results are gained by using the gears to keep pedaling in the 60 – 70 RPM range.  (At 90rpm you’re pedaling faster than the no load motor speed, and you probably don’t need e-assist!)

Electric assist is (another) subject that divides cyclists.  In my view, if the assist makes cycling possible/practical/enjoyable, then why not!

Links:

Qld legislation: https://www.legislation.qld.gov.au/view/html/inforce/current/sl-2009-0194#sec.353B353BPower-assisted bicycles—Act, sch 4, definition power-assisted bicycle

https://electricbike-blog.com/2015/06/26/a-hackers-guide-to-programming-the-bbs02/