Canadian
Cirkit
Victoria, Australia
|
5
Published: 2026-08-23
A 72V Custom Cirkit GMAC build for cruising around town.
Planning, Parts Ordering and Initial Build
Ever since seeing David Elderton's Cirkit in the Grin customer profile video, I have wanted one for myself. I contacted the manufacturer of the bike in Indonesia, but never got around to getting an order submitted with them. A few years later I came across a bike shop 10 hours away that had a Cirkit frame on a pallet for sale for $400 AUD. I asked if they could courier the frame to me and a couple of weeks later the bike frame was on my doorstep.
I then set about ordering the front rim, tyres, spokes, handle bars, brakes and worked on getting all those components installed.
I spent a bit of time on Grin’s Motor Calculator and ended up ordering a laced up GMAC 8T and a Phaserunner with the plan to run it on 72V. That combination had a good balance of torque and top speed for my needs.
Custom Parts
After my Grin components came in, I got them installed on the bike and then tackled the torque arm. I wanted to try out some of the new CNC services available on the internet and decided to design a custom torque arm in Fusion 360. I tested the arm by 3D printing it and testing fitment on the bike and then submitted it to the CNC service once I confirmed it would work.
The next stage was to tackle the battery. I settled on a 20s4p battery using Samsung 25R cells and a JK BMS. I ordered all the parts to make the battery and spot welded it together using a kweld I purchased to upgrade the Auspost Postie Bike I also have listed here on the project gallery.
Wrapping Up
I installed the battery, programmed the Phaserunner and the Cycle Analyst and everything ran great! Everyone that rides it wants one of their own, It's a lot of fun.