Rotor Systems Crank - Bike Magic

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Rotor Systems Crank

Fresh out of the box

We’ve just taken delivery of this curious-looking device. It’s a Rotor Systems crank, a Spanish invention designed to eliminate the “dead spot” when pedalling. If you’ve ever tried to ride up a hill that requires you to get out of the saddle and grind the pedals around at a glacial rate, you’ll be familiar with the dead spot, the point at which the crankarms are vertical and it takes a real effort to get them round so you can actually apply any power.

The Rotor gets around this by articulating the two crank arms – they’re not fixed at 180 degrees to one another as usual. They sit at 180 degrees most of the way around a pedal revolution, but when one crank is about to reach bottom dead centre a cunning arrangement of cams and levers swings the other one over the top ready for a new power stroke. So both cranks are never vertical.

It’s an intriguing concept, and Rotor Systems makes some bold claims for it – three minutes advantage every hour, 5% drop in heart rate, 15% drop in lactic acid production. On the downside, it’s something like 250-300g heavier than a regular crank and it’s kind of pricey – 385 Euros, which we think is about £270.

But there’s only one way to find out if it’s any good, so we’ll go and find a bike to attach it to and see how it performs in the real world… In the meantime, take a look at for more information.


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