Motorcycles

Zero Motorcycles adopts radical 'Big Hole' technology to boost range

Zero Motorcycles adopts radical 'Big Hole' technology to boost range
That massive duct running through the entire length of the WMCSRS reduces drag by a not-too-shabby 10 percent
That massive duct running through the entire length of the WMCSRS reduces drag by a not-too-shabby 10%
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That massive duct running through the entire length of the WMCSRS reduces drag by a not-too-shabby 10 percent
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That massive duct running through the entire length of the WMCSRS reduces drag by a not-too-shabby 10%
A custom fork shroud improves airflow through the front into the duct
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A custom fork shroud improves airflow through the front into the duct
Air flows in from behind the front wheel and out above the rear wheel
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Air flows in from behind the front wheel and out above the rear wheel
Beyond the efficiency and speed gains, the bifurcated duct is also a rather fetching design detail
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Beyond the efficiency and speed gains, the bifurcated duct is also a rather fetching design detail
Rather than a single Venturi tunnel like on the WMC250EV, the WMCSRS features a vertically bifurcated duct
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Rather than a single Venturi tunnel like on the WMC250EV, the WMCSRS features a vertically bifurcated duct
Want your bike to go faster? Poke a big hole in it
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Want your bike to go faster? Poke a big hole in it, says WMC
View gallery - 6 images

UK-based R&D shop White Motorcycle Concepts (WMC) 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 this method can serve as an effective way to increase EV efficiency.

It's not the first time WMC's tried this. The company's WMC250EV, designed around founder and rider Robert White to achieve land speed records, is designed around a massive Venturi tunnel running all through the center for a remarkable 69 percent reduction in drag. The bike should be able to hit 250 mph (402 km/h) – but we haven't seen anything from the company about that since the machine began track tests in 2021.

The same year, WMC also poked a hole in a 3-wheel hybrid police scooter prototype based on Yamaha's tilting Tricity 300. Its electric assist and aero tunnel combine to cut 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 hole in it. The fully faired, US$21,000 Zero SR/S achieves a decent 124 mph (200 km/h), and can manage 171 miles (275 km) on a single charge as standard.

NEW WMC Zero SRS INTELLIGENT AERO PROTOTYPE (WMCSRS) concept to boost electric motorcycle range.

"When I first saw the Zero SR/S frame and battery architecture, I immediately recognized the opportunity to retrofit a duct," said White. And that's exactly what WMC did on what it's dubbed the WMCSRS concept.

The company installed a custom vertically bifurcated aerodynamic duct running directly through the center of the bike, to channel air in from behind the front wheel and out above the rear wheel. A bespoke front fender and fork shroud improve airflow through the duct.

It's unclear whether any battery capacity was sacrificed to free up space in this instance, but WMC tells us the modifications reduce the SR/S's drag coefficient by a full 10%.

Air flows in from behind the front wheel and out above the rear wheel
Air flows in from behind the front wheel and out above the rear wheel

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

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

In the SR/S's case, that would theoretically take it from 171 miles (275 km) to 180 miles (290 km). That's not a huge boost, but hey, I'll take every chance to avoid topping off a battery on the road that I can get.

A custom fork shroud improves airflow through the front into the duct
A custom fork shroud improves airflow through the front into the duct

Mind you, this rule of thumb ignores a lot of the complexities around aerodynamics. As Amateur Aerodynamics points out, reality is a lot more complex.

One key point is that the overall drag working against a motorcycle varies with the square of speed – so reducing the drag coefficient of the bike doesn't do much at all if you're bimbling around the back streets at 25 mph (40 km/h). But once you're doing highway speeds or higher, the efficiency gains start stacking up.

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

Beyond the efficiency and speed gains, the bifurcated duct is also a rather fetching design detail
Beyond the efficiency and speed gains, the bifurcated duct is also a rather fetching design detail

There's no word as yet on whether this 'big hole' retrofit is going to be worked up into an aftermarket option for Zero owners, or whether Zero plans to roll it in as a factory option. But it's definitely something WMC is looking to license to motorcycle companies.

If the numbers add up, we might see more bikes across brands adopt central ducts soon enough.

Source: WMC

View gallery - 6 images
12 comments
12 comments
jimbo92107
A big tube down the middle? How much longer before they make an afterburner...? ;-)
johanschaller
Not only efficient. That's also a very nice looking electric bike.
Daishi
I wonder what the costs of "license to motorcycle companies" are? Do they own the idea of any "big hole" for motorcycles or are there specific design considerations to theirs that they have patents on? I sent Zero a similar proposal years ago for a fairing pass though vent that was intended to improve aero like this but also blow the air channel over the electric motor fins to avoid thermal throttling issues they had at the time. I know from their response that this was something they had considered doing as gas bikes have had similar fairing air channels for cooling and forced air for ages.
Username
No actual numbers usually means little or no results.
Karmudjun
Looks to me like they can improve handling by actually harnessing the Venturi effect to pull more air in from below, increasing the tire adherence! Yes, that would defeat some of the improvement in mileage and speed, but consider the effect on handling - especially in wet weather or the cold weather riding! Marvelous improvement in electric engine-cyling!
veryken
They should make the hole shaped like a big Zero.
Gordien
At first, I wondered why just clever fairings wouldn't achieve the same thing - must be the Venturi effect. I wonder more why I don't see techniques like this on cargo and campervans, vehicles that really need help. Great idea though.
Nobody
Since most of my riding is local at 45 mph or less, that big hole would make a nice storage addition for a light jacket or rain suit. Maybe even a lunch box.
MCG
I wonder if making the hole more slippery with say a Teflon or some other coating would be worth while? At least to allow debris to slip on by.
Lucky2BHere
What's possibly holding up testing? 2-3 full charges, do a bit of measuring? Should at least get a close idea, no?
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