The Sinclair C5 was Sir Clive’s famous first venture into electric mobility, a recumbent electric-assisted tricycle which would have been hardly unusual in 2025. In 1985, though, the C5 was so far out there that it became a notorious failure. The C5 retains a huge following among enthusiasts, though, and among those is [JSON Alexander, who has bought one and restored it.
We’re treated to a teardown and frank examination of the vehicle’s strengths and weaknesses, during which we see the Sinclair brand unusually on a set of tyres, and the original motor, which is surprisingly more efficient than expected. Sir Clive may be gone, but this C5 will live again.
We’ve had the chance to road test a C5 in the past, and it’s fair to say that we can understand why such a low-down riding position was not a success back in the day. It’s unusual to see one in as original a condition as this one, it’s more usual to see a C5 that’s had a few upgrades.
Wow this got popular, I haven't really done a massive writeup like this since I was working on the PDP-11, and I forgot to finish that in the excitement that followed when I got it to boot, so now I feel obliged to continue.
Sadly I can't really do much active tests without the battery; I ordered one from Halfords for next day in store pickup, but that was on Friday, and still no word; for now it's just a standard 12v lead acid car battery just to make this thing go, but I at least for now know the control electronics are working from my rather flawed test with the power supply.
I'll take this time to talk a little more about the C5 and what I'm planning on doing with it. To start, I've had a couple of people repeat some misconceptions about the C5 and question why I am doing this.
The C5 uses a custom motor made by the Italian company Polymotor, who did make washing machine motors, and also torpedo motors; it very likely needed this custom motor as for the time, it's efficiency is incredible...
In 2022 I used to make a daily 10 mile (16km) round commute on a first generation Pure Air e-scooter, it could just about manage it doing 13mph (20km/h), coincidently, this is almost exactly the average performance and range of the C5 with it's original 80 AH lead acid battery, and yet the Pure Air is 40 years newer, weighs half as much and is absolutely packed full of lithium batteries!
