British R&D workshop White Motorcycle Concepts (WMC) has punched a gaping hole in a Zero SR/S electric motorcycle to reduce aerodynamic drag by 10%. The prototype now goes faster and can deliver extended range at highway speeds – proving that this method can be an effective way to increase the efficiency of electric vehicles.

This isn’t the first time WMC has tried this. The company WMC250EVdesigned around founder and pilot Robert White to achieve land speed records, is designed around a massive Venturi tunnel running through the entire center for a remarkable 69 percent drag reduction. The bike should be capable of reaching 250 mph (402 km/h) – but we haven’t seen anything from the company on that since the machine began track testing in 2021.

The same year, WMC also punched a hole in a 3-wheel hybrid police scooter prototype based on Yamaha’s tilting Tricity 300. Its electric assist and wind tunnel combine to reduce carbon emissions by up to 50% compared to a conventional two-wheeler.

Now, WMC has teamed up with Zero Motorcycles to see how much extra range can be squeezed out of an electric streetbike with a big holeshot. The fully-faired Zero SR/S, at US$21,000, hits a decent 124 mph (200 km/h) and can travel 171 miles (275 km) on a single charge as standard.

“When I first saw the frame and battery architecture of the Zero SR/S, I immediately recognized the opportunity for a conduit retrofit,” White said. And that’s exactly what WMC has done with what it calls the WMCSRS concept.

The company installed a custom vertically bifurcated aero duct running directly through the center of the motorcycle, to channel air from behind the front wheel and outwards above the rear wheel. A custom front fender and fork fairing improve airflow through the duct.

It’s unclear whether battery capacity was sacrificed to free up space in this case, but WMC tells us the modifications reduce the SR/S’s drag coefficient by 10 percent.

WMC

According to WMC, this could be an inexpensive way to increase range without having to wait for battery technology improvements. The conduit is relatively affordable to manufacture and integrate into bikes, and can also help increase top speed as well as acceleration.

WMC hasn’t mentioned exactly how much range increase you’ll get with its patented conduit. There’s a rule of thumb that suggests that a 10% reduction in drag coefficient will get you something like a 5% improvement in range.

In the case of the SR/S, this would theoretically increase it from 171 miles (275 km) to 180 miles (290 km). It’s not a huge boost, but hey, I’ll take any chance I can to avoid recharging a battery on the road.

WMC

Be careful, this rule of thumb ignores many complexities related to aerodynamics. As Amateur aerodynamics points out, the reality is much more complex.

A key point is that the overall drag exerted on a motorcycle varies depending on the square speed – so reducing the bike’s coefficient of drag doesn’t do much if you’re riding down alleys at 25 mph (40 km/h). But once you reach highway speeds or higher, the efficiency gains start to add up.

Electric motorcycles are already extremely efficient in stop/start urban traffic. Highway speed is where your battery percentage really starts to take a hit, so drag reduction ideas like this could potentially have a bigger impact than the rule of thumb above could suggest.

WMC

It’s not yet clear whether this “big hole” retrofit will be made into an aftermarket option for Zero owners, or if Zero plans to bring it in as a factory option. But it’s certainly something WMC is looking to license to motorcycle manufacturers.

If the numbers add up, we could see more bikes from all brands adopting center tubes soon enough.

Source: WMC