Designing the Swingarm and Battery Holder

There aren’t any conversion kits for Bellas, so this is where the real fun begins; designing! The result of this step is learning the actual size of the engine, wheels and battery storage of your EV conversion.

The first step is to measure. If you’ve read other parts of TechDesginWorks you know I started as a woodworker, so I use a time-honored method called a “story stick” (in this case I used roll up plastic sheeting) to note all of the important measurements. With this information I can cut components by hand or with my CNC and not have to remeasure.

I might as well measure every conceivable spot to place a battery while I’m at it:

I always try to determine the largest rectangular areas available because most components are rectangular:

My first set of prototypes lets me finalize the swingarm, tire, shock and spring relationships.

Now to cut the second iteration of swingarm supports on the CNC:

These are the battery supports, which will replicate the original engine dimensions and serve as stressed members of the frame:

These look good. The actuals will be made from 1/4″ (6.35mm) and 1/2″ (12.7mm) 6061 aluminum, which I will cut on the CNC with a different end mill (like a drill bit for a router):

Now to determine the maximum battery size. For this I use CAD (Carboard-Aided-Design!). The battery could be heavy, so I want to make a “sliding” design that’s easily removable. A permanently mounted one might gain me extra space but might also require extensive dismantling of the bike if I ever need to remove it.

I need space for components too. Look at all this space!

Size determines range. This size should be good for a nice long ride. I’ll send it off the to battery manufacturer to get a quote.