How bike helmets have evolved over the past two centuries
The first head protection concept introduced to the biking world was a hat made from pith, which is the spongy rind found in ...
Yahoo10 天
The evolution of bike helmets: From plant rinds to high-tech materials
Then, they'd cover the hats in canvas as a form of weatherproofing ... Then, in the 1970s, a nonprofit dedicated to testing ...