Carbon fiber EV wheels will be lighter, quieter and more efficient

Carbon Revolution Factory Wheels
Enlarge / These carbon fiber wheels have finished the molding process.

Carbon Revolution

You may have noticed that car wheels have gotten quite large over the past few years. Designers love putting big wheels on cars, especially big trucks and SUVs, because they help make big vehicles look smaller. Expect the trend to continue as electric vehicles proliferate – it’s particularly good at helping to hide the extra height of the lithium-ion cell slab between the axles.

The problem is that big wheels may look good, but that aesthetic comes at a cost. A bigger wheel is heavier, and it’s the worst place to add pounds if you’re concerned about handling, because it’s unsprung mass. That’s why some wheels are made of aluminum alloy instead of stamped steel, but even aluminum wheels weigh a lot if they’re 22 inches in diameter or larger. Enter Carbon Revolution and its carbon fiber wheels, court side.

Originally an aerospace industry toy, the automotive industry first started using carbon fiber composites via racing. Extra weight is the enemy of a good lap time, and F1 designer John Barnard found he could build cars at least as strong as steel and aluminum ones, but much lighter. . Initial fears for the safety of naysayers proved unfounded, and for several decades it was the material of choice for prototypes and single-seater racing cars.

Carbon fiber isn’t quite as ubiquitous in road cars, but it’s there if you know where to look. Many hypercars feature carbon fiber frames, and you’ll find body panels made of this material in some performance cars.

It took longer for someone to make carbon fiber wheels, but that too happened first in the crucible of racing. But not Formula 1 – in this case the breakthrough actually happened at a Formula SAE team at Deakin University in Australia. In 2004, Ashley Denmead and her teammates were looking for a way to get a lot of mass out of their car, which the previous year weighed 750 pounds (340 kg) (for Formula SAE).

Cutting the unsprung mass in particular was critical. “It made us recognize pretty early on that the wheels you can buy for these cars really weren’t appropriate for the vehicles,” Denmead explained. “No one makes a wheel suitable for a weight of 200 kilograms [440 lb] auto. The size wheels we were using are suitable for you know, 1,200 kilograms [2,646 lbs]cars, so we thought we should try making our own wheels, which seemed like a good idea at the time.”

The design was refined over the following years’ competitions, until Carbon Revolution (originally known as C Fusion) was founded in 2007 when Denmead – Carbon Revolution’s engineering director – and his colleagues graduated.

The stock Formula SAE wheels were hand-built, with brushed resin. Today, Carbon Revolution uses a resin transfer molding process, which we’ve seen used by companies like McLaren and Lamborghini for body panels and even chassis tubs.

Carbon Revolution uses a resin transfer molding process at its factory in Australia.
Enlarge / Carbon Revolution uses a resin transfer molding process at its factory in Australia.

Carbon Revolution

“There’s a lot of dry fiber automation, both cutting, preforming, assembling these dry fiber preforms with robots, winding the rim with dry fabric onto a roller, and then the tools come together and we inject the resin through the fiber.And we can have full control over the resin system, full control over the curing, and full control over the dry fabrics and fibers that we buy and we let’s specify,” Denmead told me.

Until now, Carbon Revolution wheels have primarily adorned high-end performance cars, being fitted as original equipment on select Ferraris, as well as the Ford GT500 and upcoming Chevrolet Corvette Z06. For track-focused machines like these, lighter wheels equal more precise handling and therefore faster lap times. But for an EV, the objective is more autonomy.

The aerodynamics of a wheel is actually much more important than its weight when considering EV applications. “We can have unique wheel designs that are very aero front ends that are pretty tight without being really heavy,” Denmead told me.

“If you do these designs in metal you usually get a really, really heavy wheel because they have minimal thicknesses, and if they sink these wheels you can’t have thin features because you get cold hits and things like While obviously with the carbon fiber build you can have very thin shells if you want or very thin features that look like wings on a wheel that have no real structural integrity behind them , and you get the aerodynamic performance you want,” he said.

An unfinished wheel is inspected during manufacture.
Enlarge / An unfinished wheel is inspected during manufacture.

Carbon Revolution

And an added bonus is that carbon wheels don’t transmit as much noise as their metal counterparts, so the overall driving experience is quieter – again something you notice in an EV.

Specifically, Carbon Revolution says a carbon fiber EV wheel could increase efficiency by around 5%, as well as reduce noise by around 5 decibels. And the weight savings are considerable: a 19-inch carbon fiber wheel can weigh 14 kg (31 lb), compared to 30 kg (66 lb) for a similarly sized alloy rim. They’re not particularly cheap, although Denmead says they’ve achieved price parity with the more expensive forged wheels.

The company has been working with OEM partners on EV-specific wheels for some time, though contracts prevent it from revealing those OEMs until they make their official product announcements. I’m definitely curious who they are.