Tonka II - 'The 2nd car' urban ebike for big kids.

Tonka II - 'The 2nd car' urban ebike for big kids.

One great thing about art is its ability to start a conversation.

This bike - far from a work of art certainly has that ability.  The massive tyres, the racks, that LIGHT, and a motor!  Why?

I've conducted many 'social experiments' in my time with ebikes.  It involves throwing someone on one, who has at that point in time never ridden one.  Within two pedal strokes, their face lights up like Christmas, sometimes a giddy shriek accompanies it.  They always come back with their mind opened.

Now, I'm not saying this bike is 'pretty' but I'd like to think it has a utilitarian beauty to it, and after many ebike conversion builds, looks less ebike and more bikepacking adventure / zombie apocalypse rig.

The true appeal of ebikes came to me shortly after my new job - as Dad.  A few years into the role, I did what most parents do, and got a wee-ride, which evolved to the kid-carrier on the rear rack, then 'the chariot'.  Some of the toughest rides I've done have been with the chariot, loaded with kid, dog and toys, into a block headwind.

After some quick googling, I found a reasonably priced entry level 'eMTB' which just so happened to be a fat bike with a Bafang mid-drive motor.   I was an instant convert. 


After dabbling with adding racks and integrating lights,  I discovered their range of mid-drive motors which you can install to any* bike.     I'd grown a soft spot for 'fat' bikes and found a viable donor, a Surly Wednesday.   A year later, this is how it looked before it went to a new home.


As is the 'nature of the beast', more than a few people asked about the build, and one wanted a Tonka of their own.


Tonka II

A seemingly rare bird now, a Surly Pugsley formed the basis for the build.   

Any sensible #parentmobile / car alternative is going to have full fenders, racks to carry supplies, and integrated lights so you are never caught out.


The SRAM X9 10 speed (confusing much) didn't have the range I'd hoped for, which is why I opted for the smaller 36t chainring.  One thing that anyone reading this hoping to replicate will discover is an aftermarket chainring is a MUST to get a reasonable chainline.   The 36t with 8mm offset met both criteria, though typically a 42t with the 18mm offset will give the optimum chainline.



Another great thing about the fat tyres is the massive volume of air.  10psi feels very firm - and should you get a slow leak, it takes an eternity for enough air to escape to the point of feeling squeamish.   Not pictured is the schraeder adapter that I keep on one valve so you can top up at a petrol / gas station.


The dropper post was a late addition to the build, and makes mounting and dismount so much easier.  Especially when loaded, or stopping at the lights.  It's a little luxury that also allows partners to ride the bike and adjust the seat height easily.


The initial plan was to house the cables in a frame bag above the battery like my first build.  I had the Blackburn Outpost frame bag in 'bikepacking' tub and realised that with a little modification it would make for a cleaner build, and keep the kryptonite of all electrical devices (water) a little further away.

The stock wiring from the battery sled, motor and lights was upgraded to XT60 plugs, soldered and heatshrunk for the same reasons as above. 


Oh yeah - the motor!

Bafang offers a range of models from 250w - 1000w in 36V-52V.  If your plan is to electrify a fat bike your options are narrowed to the BBSHD 1000w with 100 or 120mm BB widths.  

Installation is easy.  Remove the existing crankset, slide the Bafang Mid-Drive in its place, secure with the lockring, and wire it up.  Making it neat is another thing completely.

There is an optional gear-sensor, throttle and brake-sensor which I found unnecessary as I wanted a PEDAL-assisted bike.  Not an electric scooter.

You can choose between 3, 5 and 9 levels of assist, and the speed limit for the assist can be set to suit your country in the control unit.   

The 48v battery allows you more options for powering other devices, one being lights.   Some Bafang models have a 3V line out from the motor for powering lights.   The 4WD LED light bar shown is wired directly to the battery, with a switch (hidden in the frame bag) to toggle power to the unit.


Just like you might have in your car, your phone is all manner of things - GPS for navigation, music, podcasts, and making calls.  I've been using the Quad Lock case and mounts for years and there is none better - they're also based in Melburn.



Racks!  Blackburn Outpost adventure cage for holding water, Blackburn Local Basket Front rack, with nifty integrated lock holder.   A nod to my bike messenger past by keeping the keys on the bars so you don't forget them, and onto the wrist when you lock up.




Some of the other choices were a 'peesh from he-here and a peeesh from th-there' like the Pirelli saddle, Nitto Bullmoose bars, and NICE BIKE bell.



The number plate was a last minute idea,  purely for fun - like the spirit of the build, and family adventures it will assist with.  


Some of the greatest rides of my life have been on a bike like this with my kid.

Many may shake their fist, or thump the keyboard about the rise of ebikes, a myriad of reasons why 'it's cheating' and yet no one begrudges anyone from having a motor in their car, which is just another 'tool of conveyance and convenience'.

My guess is they are yet to ride one and have their eyes opened.  


Find out more about the gear above from Bafang - Blackburn Design - Quad Lock