Bend yer own crank

The search for perpetual-motion machines hasn’t entirely ended, but we still have inventors unperturbed by those so-called laws of physics. A recent example:

The cranks of a bicycle are what connect the pedals to the front gears. They’re lever arms that cyclists exert a force onto the end of, through the pedals, in order to turn the front gears. The front gears pull the chain which then spins the rear wheel, sending the bike speeding along.

Just about all the cranks on the market are a straight line from the pedal to turning radius. However a company called Z-Torque claims that their cranks give cyclists more power just by changing the crank arms into a bent shape. The problem is that physics doesn’t work like the company claims it does.

Here’s the pitch:

It is indeed true that increasing the crank length will put more torque at your disposal. However, this doesn’t actually increase the crank length in any meaningful fashion: the pedal is still the same physical distance from the pivot point, no matter what shape your crank is in.

I await the breathless announcement of a conspiracy dedicated to protecting the Bicycle Establishment by keeping this invention off the market.

1 comment

  1. Eric Fithian »

    15 January 2013 · 11:07 pm

    I had not heard of any novel contortions of the cranks before.
    On the other hand, there are (were?) those oval chainrings, intended to somewhat regularize the output through the push-coast-push cycle of pedaling….
    IF the user doesn’t mind the side effect of the attendant greater wear which that arrangement makes at the pivot point for the derailleur at the rear wheel…..!

    I’ll stick with the traditional circular chainrings and straight cranks, thank you! I have enough High Strangeness already, being on a Slipstream recumbent bike….

    Need more Warm Weather and less gotta-drive-somewhere-and-get-out-the-tools activity!

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