Category: Technical

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

Trike Maintenance – Wheel Alignments

Sometimes I’m asked about maintenance on a trike, “what sort of maintenance do I need to do on my trike” type questions. The answer in many cases is, “it depends”. Not helpful.

The “depends” varies with the cycling conditions  Riding in fair weather will put fewer demands on the trike than the all weather (and all road) triker, and the ‘smell the roses’ rider will put different strains on the trike than the performance rider. Your trike manufacturer will have recommendations regarding maintenance, check their web pages or hand book….

It’s safe to say that our trikes are pretty robust and normal bicycle type maintenance will suffice. I would suggest a look around the trike every month to see if anything is loose/worn/rusting or crying out for attention. Maybe incorporate it with a regular clean?

The area that is radically different to – ahem – “normal” bikes is the steering. Trike steering has much more in common with…*cough*…cars. The one thing we must do is to make sure the front wheels agree on the direction we are going to go. Commonly termed wheel alignment, and even more commonly “toe in”, all we are really doing is making sure the wheels are parallel to each other when in the straight ahead position.

Trike with poor wheel alignment.
Not like this!

Poor wheel alignment will make the trike harder to pedal, wear out the tyres quickly, and make the handling of the trike unpredictable. It will not cause speed wobbles or make the trike pull to one side all the time. If a trike continually tries to turn in one direction, or has speed wobbles, there are other issues that need to be investigated!

So how to check alignment? It can be done with a tape measure but it’s difficult, not very accurate, and really needs 2 or more people. Some manufacturers suggest telescopic rods to check the distance between the wheel and frame, and between both wheels. Better but still awkward. I’ve even seen recommendations to remove the tyres to do an alignment properly….

Tools

We use a telescopic rod, a large carpenters square, spanners, and a purpose made alignment tool sized to suit the average trike’s track and setup for 20” diameter wheels. With this tool it is easy to read and set the toe-in to within ½ millimetre.

Alignment tools
Grubby floor and old tape is optional

To the procedure (Batman)…

Note, this is written with indirect steering and no suspension in mind, but the basic process is applicable to all tadpole trikes.

Setting it up

Somehow secure the handlebars in the straight ahead position. I use webbing tie down straps, and a large carpenters square to get the handlebars as near as possible straight ahead. Pump the tyres up nice and hard merely to minimise any difference in diameter.

Trike with handlebars secured
Carpenter square gives visual reference for handlebar position.

Measure from each wheel to the frame main tube and choose which one is closest to parallel to the frame. I normally choose the left wheel as then I don’t have to try and measure around chains and idlers. Using the telescopic rod, adjust the track rod until the wheel is as close as possible to parallel to the frame centre line. Tighten the adjustments then leave it alone!

Measuring from wheel to frame
Like this…

Put a bit of masking tape on the tread of each tyre, and mark on the tyre a reference point, a cross for instance. (This doesn’t have to be on the centreline as we’ll be using the same mark for measuring both the front and rear distances.)

Reference mark on tyre
X marks the spot

Place our special tool in front of the tyre, set the taped mark of the right tyre and the fixed pointer of the tool against each other and secure the tool in position with the rubber band.

Alignment trammel in front of trike
Like this!

Measure it

On the other wheel, rotate the wheel until the tape mark aligns with the ruler. Read off the measurement and record it. Let’s imagine it says 90mm. (Or in this case 74…)

Reference measurement
A sharper pencil would help

Take the tool off the tyre, now roll the trike forward (or back) ½ a wheel revolution. Slide the tool under the trike, and position it against the tyres again. The fixed pointer will be against the trikes left tyre this time. Line up the pointer and mark, and rubber band it in position, read off the measurement at the other wheel. Our imaginary reading for this wheel is 50mm.

Now the math! Subtract 50 from 90, divide the answer by 2, and add the result on to 50. In this case we get 70. That’s the measurement we want for the wheels to be parallel.

Here’s the really neat bit. Sit on your trike, and looking at the scale adjust the track rod (of the wheel we didn’t set straight ahead remember) and watch the measurement change. Set it at 70mm, (or maybe 70.5 to 71mm to give a touch of toe in), lock the adjustments and that’s done. (Make sure it didn’t change during the tightening up process 😊)

Final alignment measurement
Set and done.

Test it!

Take the tool off, make sure all the nuts are tight and go for a quick ride up and down the road. Leave the tape in place for this ride, if the alignment is poor it will show scuffing and tearing, but I’ll bet it looks just fine when you get back.

How often should it be checked? Not more than once a year, unless there is an incident or something starts to feel wrong.  Set it up right, from the start, and off you go!

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/