Torque Talk

The final product! – The Zenid, custom, 12mm, heavy duty torque arm made from laser-cut, 6.3mm steel (alongside the original)

I’ve taken a bit of a break from the bike in recent weeks to catch up on work and to await the delivery of some key parts for my next upgrade. I ordered a nice 18-FET version of Lyen’s controller to replace the 12-FET one I already have, and also had the current one repaired after the FET blew from the torque arm mishap.

Figuring out how to come by a suitable replacement for the rubbish torque arms that come with the hub motors turned out to be something of a journey. First I followed up a link on Endless Sphere to a guy who had custom made some torque rings that looked like they might be suitable, however they were the wrong design for the type of swing arm that the Ego and other electric scooters use.

After enquiring with a local machine shop about the cost of custom machining some suitable parts, and doing some exploring online, I eventually decided that it would be more cost-effective to simply custom design and order my own, and sell the surplus in my shop. The wonders of the internet now mean that there are manufacturers who have pretty much automated the whole process so that you can design, explore cost options, and order whatever you want with little or no human intervention. So I duly figured out how to use some web-integrated CAD software, came up with a design for my dream torque arm, and placed my order.

The CAD design, in 3D preview mode

The only thing that wasn’t automated though, were shipping options. My manufacturer of choice was a US firm (I couldn’t find any UK company who did this, alas), and the only option was for a ridiculously expensive express UPS delivery that cost almost as much as the order itself, so I emailed them and asked if I could have it shipped by a much cheaper (and slower) USPS tracked service. The said it was fine, and told me to just add a note to the CAD drawing for the

I spent the last three weeks occasionally checking the tracking to see how the package was progressing, and it seemed to take a dog’s age to crawl across the planet from from its east-coast origin. When it finally arrived in the UK it spent nearly a full week sitting in customs before finally clearing and continuing its journey. I was none too happy to be landed with an import duty and ‘clearance charge’ of nearly £40 for the privilege of this inconvenience, but duly paid it and eventually ended up with a batch of freshly minted parts on my doorstep this morning.

The real thing, next to the original that came with the motor

Here it is, the real thing, shown next to the inferior original. They’re 62mm x 24mm, and manufactured from 6.3mm laser-cut steel, and have 12mm torque slots, with a 6mm hole for the adjuster bolt, – suitable for the 1400W/1500W motors. The torque slots are slightly wider as the 1500W motor has a 16mm axle on the cable side, as compared to the 14mm on the 1400W motor, though the slot diameter required (on mine at least) is 12mm on both. I’ve also made mine longer, with a wider adjustment slot so that the rear wheel can slide back further to accommodate larger tyres. I got a batch of them, so there’s plenty left to go in my little shop in due course.

There was a moment of panic when I put it on the axle for the 1500W motor – it’s a tight fit and needed a gentle tap with a hammer to get it over the end, but then it slid down the shaft nicely, an almost perfect fit with very little free play! Here it is next to the even worse torque arm that came with the 1500W motor (these are the ones that failed).

The bike is in bits at the moment, while I repair a bracket on the battery box, respray the swing-arm, service the battery pack and fix the wiring on  the hub motor. I’ll get round to this in due course and keep you posted.