
Why don’t we fill bike tyres with helium? - wlkr
http://www.cyclist.co.uk/in-depth/791/why-don-t-we-fill-bike-tyres-with-helium
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aurizon
go flat in minutes. Helium is the smallest solitary gaseous element, as does
not form molecular aggregates, like most other gasses. Hydrogen exists as H2 =
a far larger molecule. That is why helium novelty balloons go flat in a day or
so even when they use metal lined mylar to keep the helium in.

