Purchasing new hardware? Read our latest product comparisons
ADVERTISEMENT

Offset bicycle crank boosts power

By

June 4, 2004

Image Gallery (8 images)

UPDATED March 2005 The evolution of the bicycle has never really stopped since a Parisian named Monsieur de Sirvac added a second wheel to a child's hobbyhorse in 1791 to create the "velocifere" - the pedal-less precursor to the modern bicycle. The innovative ROTOR pedal system continues this evolution by utilising independent cranks that are not aligned at a fixed 180' to eliminate the "dead point" that occurs when conventional pedals are vertically positioned.Anyone who has tackled a very steep hill on a bicycle will understand the concept of a dead point.

You always find that the moment at which you are forced to get off the bike and walk is when you are at the top of the pedal stroke - this is because at this dead point the rider has the least mechanical advantage with neither leg able to transmit any power. So if heading uphill, with no momentum to compensate, you find yourself getting out of the seat to increase leverage (or giving in altogether) at this dead point.

The ROTOR system solves this problem by using cranks that never allow one pedal to coincide at 180 degrees to the other. The independent cranks that are synchronised by means of an exocentric axel and two rods, which vary the transmission ratio during the cycle and prolong the power stroke phase for a more efficient transfer.

What all this means in real terms is that by the time one crank is at the bottom of the stroke and in the six o'clock position, the opposite crank has been accelerated through to the one o'clock position and has already started the power stroke phaseIn addition to increasing efficiency, traction and maintaining a smoother cadence, the ROTOR system reduces the risk of knee injuries and tendonitis that are attributed to the leg pushing on the upper dead point.

According to the manufacturers, tests on the ROTOR have demonstrated a real increase in power of up to 16% (equivalent to an average advantage of 3 minutes in an hour), and a resultant reduction in lactic acid and cardiac effort.Rotor cranks are currently approved by the UCI (Union Cycliste Internationale) and are designed to fit all commercial frames and accessories on the market and road (double and triple discs) and mountain bike versions are available.

Manufactured in Spain by Rotor Componentes Tecnol'gicos S.L., the Rotor system is available in most countries - find your distributor here.

About the Author
Mike Hanlon Mike grew up thinking he would become a mathematician, accidentally started motorcycle racing, got a job writing road tests for a motorcycle magazine while at university, and became a writer. As a travelling photojournalist during his early career, his work was published in a dozen languages across 20+ countries. He went on to edit or manage over 50 print publications, with target audiences ranging from pensioners to plumbers, many different sports, many car and motorcycle magazines, with many more in the fields of communication - narrow subject magazines on topics such as advertising, marketing, visual communications, design, presentation and direct marketing. Then came the internet and Mike managed internet projects for Australia's largest multimedia company, Telstra.com.au (Australia's largest Telco), Seek.com.au (Australia's largest employment site), top100.com.au, hitwise.com, and a dozen other internet start-ups before founding Gizmag in 2002. Now he writes and thinks. All articles by Mike Hanlon
2 Comments

I was wondering how these would help / if they would actually help. A few months ago I accidentally put my pedals on in a way that put them off of 180 degrees and it was really awkward to pedal with. According to this study, these pedals show no significant results.

http://www.jssm.org/vol8/n3/21/v8n3-21pdf.pdf

Antoine Planche

Very similar to a eliptical chainring-equipped mountain bike I have had for probably over 20 years. It lessens the strain of the dead point through leverage. As you come down on the power stroke, the chainring is further away from center and closer to center approaching the DP! Probably cheaper to produce as well. Just shows there is more than one way to achieve the same results.

Will, the tink
Post a Comment

Login with your Gizmag account:

Related Articles
Looking for something? Search our articles
ADVERTISEMENT
ADVERTISEMENT