Rotor Cranks work by increasing the force required on the drive side crankarm which propels the non-drive crank are past the 12 o'clock point. The cyclist is now "permanently pushing" the cranks as there is no gap between when the legs take over push/recover duties, otherwise known as the dead spot.   Road Double system |   Road Triple system |   MTB system

Rotor Cranks work by increasing the force required on the drive side crankarm which propels the non-drive crank are past the 12 o'clock point ... also known as the dead spot. This happens 180 times a minute in a 90RPM ride. Or 10,800 times an hour. The cyclist is now "permanently pushing" the cranks as there is no gap between when the legs take over push/recover duties, otherwise known as the dead spot. This elimination of the dead spot allows the rider to produce more wattage and lower his/her lactate threshold.

Rotor is an innovative pedalling system that eliminates the dead point. The dead point of conventional pedalling is the void that occurs when the pedals are vertically positioned (one at the top and the other at the bottom), which is a moment at which neither leg can transmit any power.

The dead point limits the cyclist's performance, causes tendonitis and injuries to the knee, as well as discontinuity in the traction. Rotor System provides the definitive solution to this inefficiency, which is typical of conventional pedalling, by definitively eliminating dead points.

Rotor makes the cranks independent in such a way that they are not aligned at a fixed 180º, but rather the angle between them varies during the cycle in such a way that one pedal never coincides with the one below, thus avoiding power vacuums. Such an effect is achieved by the use of independent cranks that are synchronised by means of an exocentric axel and two rods, which vary the development during the cycle and adapt to the muscle power of the legs at all times. By eliminating the dead point, Rotor optimises the effort of the cyclist and reduces the risk of injury, providing a notable increase in performance and more comfortable and healthy pedalling.

By eliminating the dead point, the Rotor system maximizes performance, as shown by scientific studies carried out by prestigious international universities. The results demonstrate that Rotor achieves a real increase in power of up to 16% (equivalent to an average advantage of 3 minutes in an hour), as well as a reduction in lactic acid and cardiac effort.

a) Reduction of lactates: Rotor reduces the concentration of lactates in the blood thanks to greater muscular efficiency, thus reducing fatigue.
b) Reduction of cardiac effort: Consequently, as a result of the reduction of lactates in the blood, cardiovascular demand is less.
c) Reduces knees injuries: Conventional pedalling subjects the knee to great articulatory stress when the leg is pushing on the upper dead point. By eliminating the dead point, Rotor reduces the typical knee injuries of the cyclist, due to less stress on the knee tendon. Thanks to the variation of the development during the cycle, the push is more progressive and the articulatory stress is more uniform.

Rotor can be fitted to all the frames and accessories commercialised on the market, and is available in road (double and triple discs) and mountain bike versions. Rotor can be adapted to all user's profile and use, whether leisure or competition, thanks to an exclusive regulation points system.

The Rotor Crank system offers improvements in a cyclist's efficiency and power development, and is simple enough to be retrofitted to almost any bicycle. The Rotor system optimizes the angular rate of each crank independently in addition to providing variable effective chainring size. Varying the angular rate of the legs may sound a little odd at first, but it actually makes a lot of sense. Just as the swimmer's arm is slower when it is in the water, pulling against the load, and faster when it is recovering through the air for the next Power Phase, the Rotor System enables the cyclist to spend more time in the Power Phase. By virtue of its mechanical linkage, the Rotor System allows the cyclists to spend more time generating power during one revolution. The variance in angular rate is subtle to the rider, however, making the Rotor Crank System easy to adapt to.

You might think that spending more time in the power stroke is going to make the cyclist more tired. Actually, the opposite is the case. The kinematics of the Rotor system enable the cyclist to develop more power for a given level of effort by increasing the effective chainring size for the pedal down-stroke (power phase) while decreasing the effective chainring size for the pedal up-stroke.

The graph below shows that the power generated by a cyclist with a conventional crank system is not consistent around the entire pedal stroke (blue curve). A conventional crank arm is a fixed length, making the power generated by the cyclists directly proportional to the power generated by the leg for an entire revolution. The figure also shows a computational analysis of the benefits of the Rotor system (red curve) with a rider expending the same amount of effort as the blue curve. You can see that the Rotor system provides increased power for the majority of the revolution.

The Rotor system also varies the angular rate of the crank to provide more time in the power stroke and less time in the up-stroke. This is accomplished by allowing the cranks to move relative to each other. As one crank finshes its power stroke, the other leg has already entered the power stroke.

This eliminates the dead spot that occurs when the cranks are vertical, with one leg at the end and one at the beginning of the down stroke.

Single Speed RS4X
The chainline of the RS4x MTB crankset is 50mm.

You can use the RS4x MTB Crank for a single chainring version by installing the 34T on the middle position and use a RS4X bash guard that mounts on the outer position, and a blank (24T chainring with the teeth machined off) for the inner position. You can purchase the RS4x complete with these items or purchase the items separately online.

The benefits of the Rotor System have been evaluated in the laboratory by Dr. Cordova of the University of Valladolid, Castilla-Leon. In his research, Dr. Cordova performed back-to-back comparisons of the Rotor system and conventional cranks. He found that for a given effort level, the Rotor system increased power up to 16%. He also found that for a given power output, the Rotor system reduced lacate production by 15% and heart rate by 5%, indicating improved efficiency. He concluded that the Rotor system is a real advantage.

The mechanical linkage of the Rotor system does weigh as much as 460 grams more than competing crank/bottom-bracket sets depending on the level of the crank. But, if Dr. Cordova's findings are even half right, the added weight of the Rotor system is easily offset by the net increase in power and efficiency provided to the rider.

Rotor Components is cooperating with other known Universities and scientists, and is encouraging further in depth testing and comparisons of the Rotor system cranks to traditional cranks and other inventions claiming to provide benefit to the cyclist.

This is not the typical romantic garage invention. The central idea of Rotor Cranks came from the Aeronautic Engineering School from Madrid, where some students developed an initial prototype back in 1995. After the President of the university approved the project, the University’s Manufacturing Department Laboratory helped with the creation of the prototypes.

The designers decided to establish a company to finish the development and start a business. After the first working Rotor bicycles were internationally introduced, Dr. Conconi showed a great interest on the idea and asked for a bike to use to carry out performance research. Conconi concluded that the system provides a real advantage over conventional crank systems. Dr. Alfredo Cordova from Valladolid University also proved that later versions of the system, by then fully integrated into a bicycles BB, provide a clear physiological advantage.

Rotor became a prominent component at most triathlon races around the world, with triathletes appreciating the resultant bike split improvements and reduced lactate levels at the start of following split. Many years of stuggling to get Rotor products on the bike of road pros for real world hardcore testing finally came bore its fruit in 2006, with the lanuch of Q rings. This time other sponsors stopped rejecting the use of Rotor Products.

Early versions of the Rotor mechanism were available in 1998, being manufactured by the high end component manufacturer EDR, in Spain. The early system needed a special frame because is was not possible to fit the mechanism inside a conventional bottom bracket. With the launch of the RCK in 2001, all cyclists could take advantage of the biomechanical benefits provided by ROTOR Cranks, with each following version (RS3, RS4, RS4x) improving the effeciency, quality and asthetics of the system further.

In late 2005, Rotor took a huge step and dared to go against the current once again, in launching it's Ovalized Q-Rings chainrings. After the first positive feedback from cyclists and encouraging scientific test results came back at the end of 2005, Rotor is now set to fully revolutionize the world of cycling.