Bikes, even small ones … not green!
So many people think that motorcycles are ‘greener’ than cars because they are more fuel efficient. But did you know that they are actually much more polluting?
Be aware, though, that the bikes they tested were air-cooled and carburetted. Modern bikes with water-cooling and fuel injection are cleaner.
It’s a fact – at least so far as bikes without catalytic converts (the vast majority) are concerned.
Californian tests show that bikes were on average 10 times more polluting per mile than a car. More specifically, they emit more unburned hydrocarbons, oxides of nitrogen and carbon monoxide. Carbon dioxide emissions – the greenhouse gas that is taxed for cars - however, are actually less. Carbon dioxide, of course, isn’t so injurious to health.
So why should a bike internal combustion engine that is on average about twice as fuel efficient as car's be so polluting?
Paradoxically, it’s the bike’s efficiency that’s to blame. Higher performance techniques such as higher compression ratios, higher combustion temperatures, actually liberate MORE oxides of nitrogen.
Bikes do have one advantage, however – they spend less time in traffic so, in theory, they pollute proportionally less. However, a Swiss study* by Ana-Marija Vasic at the Swiss Federal Laboratories for Materials Testing and Research shows up to 16 times more bike pollution due to hard acceleration between stop lights.
New legislation will soon be putting bikes on the same emissions footing as cars. Can’t come soon enough for me.
Take a look at this episode of the US TV series Mythbusters where they compare bikes from the 80’s, 90’s and 2000 to measure their polluting effects. The ‘myth’ they’re busting is that bikes are polluting less than cars.
Be aware, though, that the bikes they tested were air-cooled and carburetted. Modern bikes with water-cooling and fuel injection are cleaner.
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