[Note: this report is from a cycling media source, and unsurprisingly
contains mixed units that detract from clarity. The reader might wish to
speculate as to why this should be so]

Materials matter

According to the World Steel Association, there is an average of 1.9kg of
CO2e emitted per kg of steel produced.

Whereas according to the European Aluminium Environmental Profile Report,
an average of 18kg of CO2e is released per kg of aluminium produced, but
recycled aluminium has just 5 per cent the carbon cost of virgin material.

Muddying the waters further, this report from Duke University estimates
that manufacturing an aluminium Specialized Allez road frame alone produces
250kg CO2e, while making a carbon-fibre Specialized Roubaix frame produces
67kg.

<https://www.bikeradar.com/features/long-reads/cycling-environmental-impact/>

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Spike