Meet the inventor whose smart bike wheels remove pollution from the air

© Rolloe
Thought cycling was one of the greenest forms of transport? Industrial design graduate Kristen Tapping explains how her award-winning design could make riding a bike even better for the environment.
Written by Mildred LockePublished on
It’s not groundbreaking news that cycling is one of the most environmentally friendly ways to get around.
According to research by the European Cyclists’ Federation, the average bike emits 21g of CO2 per kilometer travelled – 5g for the bike’s manufacture and maintenance and 16g for the calories consumed, and subsequently burned, by the cyclist to power the pedals.
Compare this to the average emissions of a motor vehicle (271g of CO2 per passenger kilometer) and it's clear that making journeys by bike comes out on top in the carbon efficiency stakes. But can it be even greener?
Kristen Tapping Rolloe
Kristen with her invention, the Rolloe wheel
Kristen Tapping, an industrial design graduate from London Southbank University, believes it can. Her award-winning invention, Rolloe Roll Off Emissions, transforms the humble bicycle wheel into an air purifier that sucks in polluted air, filters out the pollutants and releases the clean air back out into the world – making one of the greenest ways to travel truly carbon-negative. Here she explains what inspired her idea and her future plans for her invention.

Where did the idea for Rolloe come from?

Cyclists in busy London street
She got the idea from riding around London's polluted streets
The idea came while cycling around London. In traffic, you’re really aware of the pollution: the heat, the gases and the smell. This got me thinking, air purifiers use circulation to filter air, so why not use the spinning wheels of vehicles to catch pollution in the prime place that it’s happening?

How does your invention work?

Rolloe wheel
Air is sucked into the wheel, filtered and released back into the world
The idea is to clean the air while you’re riding a bicycle amongst traffic where air pollution is the strongest.
Rolloe is a [three-spoke] mag wheel with two side attachments like car hubcaps and filters inside that catch pollution particles. The hubcaps have a cavity in the centre and fins around the edge. As the wheel spins, it sucks air through the central cavity, filters it, then pushes [the filtered air] out through the fins.
The faster it spins, the more air it pulls in and filters out. But you don’t need to be a speed machine: I tested the prototype on a fan with some incense and it even worked at low speeds.

Is it effective at reducing air pollution?

Rolloe second prototype
Kristen is now working on a third, usable prototype
I’m still prototyping, so this is all theoretical, but Rolloe pulls in 0.665m³ of air per kilometre cycled. [The London-based cycle hire scheme] Santander Cycles’ 13,600 bicycles cover on average 134,448km daily. If each of those bikes had one Rolloe installed, they would filter 79,865m³ of air per day, which is four times the size of Trafalgar Square.
Extrapolating this out, if 10% of all London cyclists had one Rolloe installed on their bike, they would filter approximately 266,865m³ of air – 20 times the size of Trafalgar Square. Imagine applying this to other cities in the UK, and other countries around the world!
If 10% of all London cyclists had one Rolloe installed on their bike, they would filter approximately 20 times the size of Trafalgar Square
Kristen Tapping
And that’s just with one Rolloe [wheel fitted to the bike]. I’d like to develop a rear wheel version to double those numbers, although it’s trickier due to the drivetrain.
Of course, we have outdoor purification systems that pull in higher numbers, but they’re usually in low pollution areas like parks. Rolloe is directly in traffic, where the air is its filthiest.

How did you develop the idea further?

The fewer times I have to reinvent the wheel, the better!
Kristen Tapping
My product design degree involved designing a 3D polymer product that provided a sustainable solution to an environmental problem, prototyping it, and demonstrating its impact.
I entered the first cardboard prototype for the Design Innovation in Plastics (DIP) award. As a finalist, I studied more research on pollution and the various elements that affect a bike wheel: crosswinds, weight, materials and external factors. From there I developed the second [DIP award-winning] Rolloe prototype, and I’m now working on the third.

What are the biggest challenges you’re dealing with?

Young woman renting bicycle on street in London
Could cycle hire schemes soon be fitted with this innovative tech?
Version three needs to be optimised for outdoor environments, so choosing weather-proof and sustainable materials is challenging. Pollution particulates vary in size, while noxious gases pass through most materials. Rolloe needs to have multiple filters to catch a variety of pollutants.

How do you envision Rolloe will work for cyclists?

The next challenge for me is to actually ride it. I have a mag wheel ready, and I’m going to 3D print the rest, put it on my bike and test it
Kristen Tapping
I’m currently focusing on bike share schemes but I want Rolloe to be commercially available for all bikes eventually.
I’m working with 700c [road bike] wheels, although I’d like to introduce other sizes later. Changing size means creating a new mould, which is the most expensive part. The hubcaps don’t need to change [dimensions] though, so they could cover several wheel sizes. I’m considering not producing the [three-spoke] mag wheel myself since they’re already commercially available, reducing costs and enabling me to expand the size range in future. The fewer times I have to reinvent the wheel, the better!

What are the next steps for you and for Rolloe?

The next challenge for me is to actually ride it. I have a [three-spoke] mag wheel ready, and I’m going to 3D print the rest, put it on my bike and test it. I can keep tweaking prototypes until I produce a commercially viable and rideable wheel with proper air filtration that can withstand the elements.
I’d work with engineers and bike specialists to optimise the airflow, make the filtration sustainable, develop the moulds to reduce cost and make it strong, and then when the design is finalised, I’d patent it.
I’m applying for the Royal Academy of Engineering Enterprise Fellowship, which ends with you pitching to investors, Dragon’s Den-style, and hopefully going to market within 18-24 months.

What advice would you give to product design students with a great idea?

  • Get feedback to make it better and check if your university runs an enterprise scheme.
  • Don't spend all your money. Use cardboard, vacuum-formed plastic, 3D printers and glue guns to prototype and finalise your design. You can also use free 3D modelling software like Fusion 360, and subscribe to Adobe Creative Cloud to use Adobe Portfolio for free website building and hosting.
  • Enter competitions! Look at the Bolt Burdon Kemp Getting Back on Track competition, enter the DIP, and the James Dyson Award – even though it’s very tough and competitive. You’ll gain so much from the experience.
  • Finally, when you see ideas like Rolloe, it’s usually not the final version – there are always improvements needed. Look past the obstacles for the possibility, and just try. What’s the worst that can happen?