The use planetary gears, same way that internal hubs work. But reading about these cranks, it sounds like they're pretty noisy when on overdrive. The ratios are 1:1 and 1:1.6.
http://www.bikerumor.com/wp-content/uploads/2008/09/bionicon-bbox2.jpg
http://www.bike24.com/images/products/p0413307.jpg
@turnpedal started
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The use planetary gears, same way that internal hubs work. But reading about these cranks, it sounds like they're pretty noisy when on overdrive. The ratios are 1:1 and 1:1.6.
http://www.bikerumor.com/wp-content/uploads/2008/09/bionicon-bbox2.jpg
http://www.bike24.com/images/products/p0413307.jpg