Pedaling is not pollution-free

Bicycles are widely recognized as one of the most environmentally friendly forms of transportation. However, taking a closer look at the manufacturing process and material waste left behind reveals that bicycles are not entirely free from environmental impacts.

Bicycles' environmental cost begins to accumulate from their manufacturing stage. Aluminum is the most common material used in bicycle frames, which requires a highly energy-intensive manufacturing process. Producing one kilogram of primary aluminum releases about 16 kilograms of carbon dioxide on average. Carbon fiber, another popular frame material, has an even larger footprint. The U.S. Department of Energy's National Renewable Energy Laboratory estimates that manufacturing carbon fiber can generate 20 to 30 kilograms of CO₂ per kilogram of material, largely because of the high temperatures and complex chemical processes required during production.

Tires generate another hidden source of pollution. As bicycles travel, small amounts of synthetic rubber gradually wear away and become microplastics. Globally, tire wear from all vehicles releases around 6 million metric tons of particles every year, making it one of the largest sources of microplastic pollution. Bicycles contribute only a small fraction because they are much lighter than motor vehicles, but they are not entirely exempt from this issue.

Consumer habits also increase environmental impacts. The global bicycle market was valued at more than US$70 billion in 2024, and manufacturers release new models every year. Many bicycles, helmets, clothing items, and accessories are replaced long before they reach the end of their usable lives, much like the prevalent issue of fast fashion. This constant demand requires more aluminum, steel, plastics, rubber, and packaging, which leads to a constant increase in greenhouse gas emissions across global supply chains.

The rapid growth of electric bicycles introduces another environmental concern. Global e-bike sales exceed 40 million units annually, and nearly all rely on lithium-ion batteries. Mining lithium, cobalt, and nickel can damage ecosystems, consume large amounts of water, and produce hazardous waste when extraction is poorly managed. Although battery recycling continues to improve, many batteries still fail to enter proper recycling systems.

Still, these hidden impacts should not overshadow cycling's environmental benefits. A typical bicycle emits only about 21 grams of CO₂ per passenger kilometer over its entire life cycle, compared with around 271 grams for a gasoline-powered car, according to the European Cyclists' Federation. Cycling remains one of the lowest-carbon ways to travel.

Instead, we must focus on ways to reduce the environmental costs of bicycles. Producers must reduce the carbon footprint of manufacturing by switching to renewable energy in factories, using recycled aluminum and steel instead of virgin metal, minimizing toxic coatings, and designing bicycles that are easier to repair and recycle rather than discard.

On the individual level, we can contribute by choosing durable bicycles, repairing worn components instead of replacing them, and supporting reasonable manufacturing and recycling practices. Through collaborative efforts of producers and consumers, bicycles can become an even more sustainable mode of transportation than they are now.