The Carbon Footprint of a Bicycle

Part 1 of Cycling to a Greener Future

The sun is just rising over the treetops. Bronzed light filters through the rustling leaves and dances across the surface of The Boating Lake in a dazzling, kaleidoscopic display. The sweet-honey smell of bluebells floats through the fresh morning air, stratifying itself with the sonata of birdsong and the humming whizz of a thousand bicycles. It’s summertime in London, and the Regent’s Park cycle loop is heaving. Like schools of Lycra-clad tropical fish, pelotons containing every colour, shape, and make of bicycle soar around the 5-kilomtre ring road that borders the park at breakneck speed, awash in pure exhilaration. This is London cycling at its finest.

In 2025, the Bicycle Association of Great Britain reported that the total value of the bicycle market in the country had risen to approximately £1.9 billion, representing a 5% increase year-on-year and marking the first instance of expansion since before the COVID-19 pandemic. Much of this growth seems to be driven by the revival of mainstream recreational cycling and the popularisation of adjacent endurance sports such as triathlon.

As sales have grown, myriad brands old and new have jockeyed for their piece of the cycling market. The bicycle market is generally segmented by frame material, most commonly steel, aluminium, and carbon; each material carries its own implications for weight, performance, durability, price tag, and the inevitable material tribalism of riders. Most cyclists would assume that cycling is one of the least environmentally impactful forms of sport and transport out there. But like any widely manufactured product, each type of bicycle frame carries its own profile of environmental impact.

To understand a product’s environmental impact, it helps to first understand how that impact is measured. The metric most frequently used by the UK government is mass of CO2e, or carbon dioxide equivalents.1 Applied to bicycle production, this varies sharply by frame material, as shown below.

Frame materialkg CO2e per kg produced
Steel1.90
Aluminium14.8 -15.1
Carbon fibre~20+
Table 1: Production emissions by frame material

Carbon fibre production is, by some distance, the most energy-intensive of the three. These per-kilogram figures don’t tell the whole story, though. Most bikes are shipped from Asia, and that journey adds its own emissions: shipping a typical bike box from Shanghai to the UK by sea adds roughly a further 7.9 kg CO2e.2

To make the comparison concrete, the manufacturing CO2e of twelve popular road bikes across seven brands was modelled, varying only frame weight and material.3 The results, shown in Figure 1, tell a slightly counterintuitive story: aluminium-framed bikes actually carry the highest average manufacturing footprint of the three materials, coming in above carbon fibre, and well above steel, the clear winner in terms of low emissions.

The Carbon Footprint of a Bicycle
Figure 1: Manufacturing CO2e of twelve road bike models from seven brands, grouped by frame material (carbon fibre, aluminium, and steel). Non-frame components held constant across all models to isolate the effect of frame material and weight.

The explanation comes down to weight. Carbon fibre may be the most polluting material per kilogram, but its strength and low density mean far less of it is needed to build a frame. As a result, despite the dirtier production process, a carbon bike ends up lighter and, on balance,less carbon-intensive than an aluminium one. Steel sits at the other extreme: heavier by far, but with production emissions so much lower that it still comes out on top overall.

There is an important caveat with carbon frame bicycles – disposal. While the emissions footprint of carbon frame bikes is typically lower than that of their aluminium frame counterparts, unlike aluminium (and steel) there are no widespread, economically viable methods by which to recycle them (Tillett, 2024). This means that many end-of-life carbon fibre bikes wind up in landfills with the potential of remaining there for centuries (Composites Construction UK, 2023).

Understanding the carbon footprint of a bicycle is an important first step in understanding how cycling as a whole impacts the environment. It underlines that, like all industrial products, there are notable manufacturing and distribution emissions associated with each and every bicycle purchase. There are also clear environmental costs in opting for models made with high-performance materials over more standard models, however these costs are not necessarily as straightforward as they might at first seem. Bikes made with steel produce the lowest mass of CO2e, followed at some distance by bikes made with carbon fibre, neck in neck with bikes made with aluminium.

Back in London, the summer sun has fully risen over Regent’s Park. Apparitions of a thousand miniature sailing ships, the riders slice through eddying pockets of mist drifting up from the grass. Frames of steel, aluminium, and carbon hit unique resonant tones in the wind, an odyssey of their unique emissions footprints. As the riders disappear once again beneath the shade of the plane trees, the mist of another question remains: once the carbon footprint of a bicycle has been accounted for, what is the environmental effect of the ride itself?

More information on the carbon footprint of a bicycle:

  1. CO2e (carbon dioxide equivalent) measures all greenhouse gases emitted including CO2, methane, and nitrogen dioxide expressed as the mass of pure carbon that would produce the same warming effect over a 100-year period. Source: UK Department for Energy Security and Net Zero (DESNZ), 2022.
    ↩︎
  2. Based on Department for Environmental, Food & Rural Affairs shipping conversion factors (16g CO2e/tonne-km) and European Bike Manufacturing Association methodology, for a 25kg bike box travelling 19,500km from Shanghai to Felixstowe by sea. Most bicycle production takes place in Asia (Eurostat, 2024). ↩︎
  3. Twelve mid-to-high-spec road bikes across seven brands were modelled, holding non-frame components (wheels, drivetrain, tyres, and so on) constant and varying only frame weight and material, using manufacturer-published frame weights where available and factoring in shipping emissions resulting from the variation in weight alone. Category averages: aluminium 91.46kg CO2e, carbon fibre 87.88kg CO2e, steel 74.71kg CO2e. ↩︎