The cyclist's pedal stroke is - not perfect. At least compared to a smoothly rotating motor. The energy released by the muscles fluctuates greatly over the course of a crank revolution. The cyclist therefore does not apply the same amount of force to the pedal in every crank position.
Goal: round kick
This pulsating performance spurs inventors on time and again to come up with technical solutions to optimise pedalling. The Spanish manufacturer Rotor is not the first to want to make pedalling "rounder" with oval chainrings. The idea is to overcome the dead centres more quickly, extend the time of the pressure phase and make the pedalling movement more efficient overall.
The rotor blades differ significantly from the best-known ovalisation attempt to date - Shimano's Biopace from the 1980s - in two respects: when the crank is horizontal, the rotor blades are highly oval instead of transversely oval; and they can be twisted within certain limits in order to adapt the pressure point to the rider's position and pedalling motion on the bike.
Pedalling feel: out of round
If you switch from the round to the oval chainring, you can clearly feel how your leg has to work against a smaller resistance at the beginning of the extension, which increases with increasing leg extension (and force). A 53-tooth rotor ring combines the effect of a round 51-tooth and a 56-tooth ring over the course of half a revolution - the latter is effective at around the four o'clock position of the crank. After a short period of familiarisation in the pressure phase, this feels quite good - heavy gears in particular are subjectively easier to shift, and you can put one less tooth on the sprocket set. With low to medium pedalling power, however, the pedalling feel with rotor blades - in our experience - remains rough even after a longer period of familiarisation. Especially in the upper part of the traction phase, pedalling patterns that have been rehearsed for years and the accelerated movement dictated by the Oval, which is supposed to force a new pedalling pattern on the rider, apparently collide.
This is not the case with roller training: here, the Q-Rings compensate for the low flywheel mass of smaller roller brakes and make the pedalling noticeably smoother.
Does the Rotor Oval make you go faster? Rotor says yes, citing an unpublished study by the University of Valladolid. In tests with cyclists on the roller, the scientists documented small increases in performance of two to four per cent during repeated sprints and lower lactate values during continuous exertion. However, the results are not statistically proven. We were unable to determine any performance gains during our rides with a power meter. Bike dealer and position expert Fritz Buchstaller from Hilpoltstein, who has already fitted many triathletes with Q-Rings, finds "that the pedalling becomes rounder and you can ride more relaxed in the aero position if the blades are fitted correctly." However, Buchstaller was also unable to measure higher wattage values.
The well-known US coach Joe Friel recommends rotor blades for "mashers" - riders who push but hardly pull on the pedals. Biomechanist and pedalling expert Wolfgang Petzke (caloped.de) is very sceptical about the reasoning behind oval blades. In his opinion, the efficiency of pedalling depends to a large extent on the correct feeling for the movement, i.e. the correct timing of the muscle activation and the resulting power of the muscle movements, and less on the shape of the chainring or the resulting forces. According to Petzke, you can also change your pedalling pattern by consciously concentrating on lifting and lowering your legs. advantages, but no guarantee.
Our opinion: The adjustable and relatively gently ovalised Q-Rings are the most interesting offer on the subject of oval blades to date. The Q-Rings smooth out the torque somewhat and promise advantages for less experienced riders in particular. However, they are not a guarantee for more speed and comfort. You can also improve your pedalling technique regardless of the shape of the chainring.
Reference Specialised trade
Info www.rotorbike.com
Costs around 180 euros for a pair of blades, versions available for all bolt circles in compact and normal
